CA1186053A - Indicating device for the parameters of a diving operation - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The indicating device is driven through at least one memory for the decompression parameters at a series of diving depths and times, and an evaluation and logic stage for the measured values of the depth gauge and timer, with the values stored in the memory. At any time during the dive the necessary total resurfacing time (15), including the prescribed decompression stops (16) which depend on the dive depths (14) and times (13), can be indicated, and/or a converter device is provided for conversion of the present bottom-time, on entering a new diving depth stage, into the equivalent bottom-time for this new diving depth stage. A
single pressure sensor, preferably a piezoresistive load cell, is used both for the atmospheric and the water pressure and can be switched to the two ranges. LED indicators light up if the maximum ascent rate is exceeded (10), when a decompression stop is reached (11), and if the equipment becomes inoperative because the permissible times and/or depths have been exceeded (12).

Description

The invention relates to an indicating device for the parameters of a diving operation9 suoh as, for example, present depth7 maxi~um diving depth reached, elapsed divLng time or the like, ~hich indicating devioe is driven through ~) at least one memory for the decompression parameter~ at a series of diving depths and times and b) an evaluation and logic stage for the measured values of the depth gauge and timer, with the ~alues stored in the memory.

During diving with compressed air~ a pressure equilibrium is established by the diving appaxatus (demand regulator). ~hi9 means~ that the air inhaled by the diver is at the same pressure as the water surrounding him.

With increasing depth of water~ the diver inh~les air at higher pressureD which causes more air to be dissolved in the body of the di~er~ ~he various ~ases~ of which the air is composed, enrich the various ti~sues of the human body to diferent extentsp according to given saturation factors~

During a~cent, the opposite occurs, the tissue~ desatlurate themselves~

~ow if the surrounding pressure falls too rapidly as a result of too ~apid an ascent~ the air di~solved in the blood and the tissues cannot be exhaled s~fficiently rapidly.

~n particular, this applies to the dissolred nitrogen, since the excess of oxygen and carbon dioxide is considerably less.
This comes about because a gTeat part of the oxygen is Gonsumed by the tissues and the carbon dioxide leaves the organlsm ~aster ~han other gases~ because of its high diffusion rate~

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If nitro~en is present in excess during an ove~-rapid pressure reduction~ it can come out of solution, forming ~ubbles~ ~his leads to decompression aickness ~ which can be a~oided, if the nitrogen is allowed to free itself so slowly from -the blood ~nd the tissues~ tha~ no gas bubble formation occurs.

~he manner in which gas-bubble formation causes illness lies in the fact that the nitrogen gas bubbles causa damage in the tissues and that they occur in the blood vessels and remain trapped in the fin~l branches of the latter, the capillaries.
qhere they obstruct the blood and oxygen supply to the surrounding -tissue~

If this condition of blocka~e of a blood-vessel ~embolism) persi~ts, the regions affected can no longer be nourished and are destroyed.

In oxder to avoid decompression illnesses, the diver must not ascend at a faster rate than 10 m/min and~ after exceeding the so ~alled zero time~ he must make pauses (decompression stops) during ascent~

The duration and depth of the decompression stops de~end on the tissue æaturation of the diver. The tissue saturation iB
in turn influenced by various factors.

Without statement of reasons and without laying claim to completeness~
let us list some of the most important points here ~ Maximum diving depth - Diving time - Course of the dive - Air pressure at the water surface ~altitude 3f the diving location above sea level) ~uration of stay at the diving location before the dive.
Previous dives withLn 12 hours ~ Physical effort under water - Individual tissue composition of the diver ~obese or athletic physique)

- 3 ~

- Composition of the breathing gas or air.

As long as the diver can xeturn to the surface at any time without the danger of a decompression illness9 he is in the zero-time diving range, The zero-time means the time for which a diver can remain at a given depth~ so that he does not hzve to make any decompression stops during his ascent.

~evertheless~ the pressure-chamber laboratory of the ~niversity of Zurich recommends that a minimum stop of 3 minutes at a depth of 3 metres should be adhered to for every di~e~

In oxder to be able to return to the surface without decompression accidentæ, eve~y diver must know the ascent conditionsO

These are the rate of ascent and the decompression intervals, which the diver must allow to elapse during ascentO

The decompression intervals depend o~ the duration and depth of the dive and must be spent at specific depths~

~t the present day~ the diver determines the ascent conditions b~ hand~ with the diver's watch9 the depth gauge and the diving table~ Determination of the decomRression intervals in the diving table is quite simple, but is also imprecise with ree~d to optimum decompression~ because simple handling o~
the tables can onl~ be obtained at the expense of a loss of exact recording of the dive parameters.

In order to obtain the optimum decompression for ever~ diving operation9 the diving sequence must be precisely recorded a~d the correspondLng decompression conditions must be calculatedO

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Naturally~ it is impossible for a diver to carry out this work himself9 because for this puxpoæe he would have to record a great number of items of data and e~aluate them by complicated calculations~ Therefore, at the present day, a teur and professional divers use tables~ from which they read off t~e decompression conditions. Such recognised tables are.~ for example, those of the - Groupe d'Etudes et de Recherches Sous-marine (~rance) - Ro~al NaYy (England) U.S. Navy (USA) - Druckkammerlabor der Universit~t Z~rioh (Switzerland)O

~hese tables are based on experiments on human subjects and on c~lculations, in which a finite number of tissues with different saturation factors have been simulated on a large computer~ .

~he xequire~ents of the dlver with regard to the table are:
. Simple handling . Decompression conditions for eve~y dive with just the necessary safety margin~

These two requirements are mutually contradictory~ because simple h3ndling of the table requires ~ew table input values, but few input ~alues m~ke exact recording of the course of the dive impossible. ~hus it is impossible to determine the decompression conditions which are just necessar~ for eve~y diveO

merefore all tables are based on the compromise~ that the few table input values are at the expense of the maximum decompression tLme and the di~er only arTives at the decompression which is just ~ece~sary in the extreme case. In all other cases~ the di~e~ decompresses for far too long~

~ 5 ~

~his mean~ that most tables obtainable at the present day are calculated for a linear descent (approxO 30 m/man)9 a stay at a ~iven depth and a direct ascent.

~hus the decompression conditions can be read from the table b~ means of the maximum depth of dive and the total diving tLme (t.ime from the beginnin~ of the descent to the beginning of the ascent)~

~ut if various tables are compared with one another, it is found9 that considerable differences occur with regard to the decompression conditions for the same total dive time and the same maximum diving depth~

This comeæ about:
- Because most tables are designed for diving at sea level and diving in mountaLn lakes can only be taken into account with_ difflcultyJ quite apart from variations in atmospheric preQsure due to weather conditions;

- because dives preceding a present di7e canno~ be taken înto account at all with many tables, and with other tables they can only be taken into account with difficulty;

- because the decompressîon conditions depend on the duration of the ~tay at the diving location and on the altitude of the diving location abo~e sea level~ and thi~ is not taken into account in all tables;

- be~ause only very few tables take account of an altitude Xange9 for ~hich the decompression condition~ ~re valid~

- because the various publi~hed tables have had a safety factor of Yarying m2gni~ude ~pplied to them~

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~ables 1 to 4 for 0 - 700 m abo~e sea level and 5 to 8 for 701 - 1500 m above sea level are to be found at the end of the description.

~he main differences of the tables of the Pressure Chamber Laboratory of the University of Zurich (Druckkammerlabor der ~niversit~t Zl~ich~, as compared wi-th ~ll other tables, are~

1. The tables of the Pressure Chamber Laboratory are unique in that they t~ke account of a wor~ factor, i.e. these tables are so designed, that a diver, who carries out physical work under water~ can decompress in accordance with these tables without danger of a decompression accident, 2. ~he tables of the Pressure Chamber Laboratory are among the few exceptions, which are not designed for one imaginary altitude abo~e sea level, but for an altitude range above sea level~

Since~ on the one hand~ the tables are complicated, but on the other hau~d they require a large number of items of measured data, the most widely va~yi~g devices and aids for the diver have been developed~ ~part from differerlt kinas of depth gauges and divers~
watches, these include~ for example, a decompression meter, an instrument which simulates the gas saturation of the body~ by the ~act that gas is pressed out of a flexible bagJ throu~h a piece of sintered ceramic9 into a rigid-walled chamber~ ~
pressure gauge cormected to this chamber indicates the pressure in it~ ~he longer and the deeper the instrument is ta~erl during a divel the hi&her is the rise in pressure behind the sintered plugo The pressure gauge thus gives the diYer approxLmate information on the progressive ~aturatiorl of his body tissue~

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Since the decompression measuring instruments obtainable at the present day can only reproduce the ~aturation of the human body tissues very inaccurately, this instrument must never be used alone for the determination of decompression. At present this must always be determined with the aid of further factor such as diving depth and duration, by means of a decompression table before every dive. Therefore the "~ekometer" can at best be carried for checking purposes. The reason for thi~ lies in the fact that decompression meters work in accordance with 30yle~ riotte's law and can only simulate the effect of nitrogen under high pressure on the human body~ Decompression meters can never work accurately, because the gae diffusion through the sintered filter takes place at the same rate in both directionsJ
In the human body, however (especially during dives of short duration) uniform conditions never occur. A decompressio~ meter is no guarantee for the prevention of a decompression accident.

Another common measuring instrument is the so-called bottom-timer.
~he bottom -timer is a~ automatic instrument for measuring the diving time~ It is pressure-controlled and thus switches itself on automatically o~ reaching a calibrated depth. In the same wayt the bottom-timer switches itsel~ off again shortly before reaching the water surface. It is in fact nothing more than a watertight "stop~watch", which switches itself on and off through a simple - pressure-controlled - mechanism. ~he bottom timer informs the diver of the effective diving time. ~owe~er~ this diving time can also be read from a normal diver'~ watch (settable by a setting ring)~

Diving time and diving depth are indeed si~nificant, but -they are not the only factors for the determination of decompression~

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On the other hand, a diving computer could acquire all data exactly and could evaluate it accordingly. It would be ideal, if the divin~ computer simulated a di~er, composed of a finite number o~ stan~rd tissues~ ~hen the degree of saturation of the indi~idual tissues~ as a function of the depth and the saturation factor of the tissue concernedg would be integrated against time. Ihrough continuous comparison of the critical degree of saturation with the degree of saturation of the indi~idual tis~ues reached up to that time9 the decompression conditions could be deter~inedc Now a proposal has already been made for an ideal deco~pression mete~ in a~alog technique~ making use of RC elements to simulate the degrees of saturation of the individual tissues. In this case9 however~ problems arise on the one hand, in that the degree of saturation cannot be converted, by calculation9 into the equivalent decompression conditions,-and on the other hand the process of saturation and desaturation of the tissues ca~
only be reproduced to a limited extent throug~h~C networks~
because the ~arious tissues ha~e nitrogen half-~alue times o~

5 to 635 minutesO Ihis demands enormously great time constants of the ~C eleme~ts (up to 635 minutes), which leads to very great problems with regard to the design of the ~C elements~
Over and above thi~ the proposed aDalog processing would be much toa inaccurate for practical use. ~herefore this proposal has 8180 never been i~plemented~

Various diving computers are indeed al~eady comrnercially available, but hardl~ any advance has been achieved with these, beca~se diving computers 80 f æ produced did nothing more thsn the digitalisation of all previousl;y known inRtruments rsuch as depth gauges, bottom-timers~ decompression meters). Abo~e all, all p~eviously known devices are subject to the disadva~tage that they only ts~e account of the maximum diving depth reached ana ~he maxlmu~ diYing time aæ parameters for the determinatio~

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6~3 of the decompression conditions. This means, that according to the indication of these devicesl a diver must adhere to the same decompression conditions, irrespective of whether he spent most of the time at shallow depths~ perhaps even at a zero-time depth, and only reached the maximum diving depth briefly9 or whether he spent the whole diving time at the maximum depthO

The result of this inaccurate indication is that divers make deductions from the indicated decompression conditions on the basis of the actual times and depths, which again the~
-themselves only estimate and thus run into danger.

The invention is based on the problem of making it possible to indicate the decompression conditions more accuxately on the basis of the ac-tual diving times and depths. According to -the inVentioD this is achieved by the fact that~ at any time during the diving operation, the necessary total ascent time~
depending on the depths reached and times elapsed in the dive and including the specified decompression stops, can be indicated and/or a converter device i9 provided for the actual bottom-time in each case, on entry into a new diving depth stage9 to convert into the equivalent bottom-time of~this new diving depth stage~

In order to increase the accuracy of the indicating device still further, additional provision is made for the air pressure, preferably to be measured with a measuring instrument, to be taken into account with the aid of the converter device.

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~hus the air pressure actually present at the diving location, dependin~ not only on the altitude9 but also on the weather conditions, can also be taken into accountO Pre~iously it was - 1o -only possible to use very widely graduated tables, differing according to altitude, while the weather conditions, which h~ve a very great influence, were not taken into account at all~

~ow it would be conceivable to use two different pressure ~auges, one to measure the water pressure and the other to measure the air pressure9 but preferably provision is made, for a single pressure sensor, preferably comprising a piezoresistive load cell9-to be connected to -the circuit containing the converter device, both for the air pressure and the water pressurec ~hus not only can costs be saved for a further pressure sensor, bu-t the handiness of the device i8 ~lso maintained~ which is irnportant for ca~rying under water~

~ut if a single pressure sensor is used for pressure measurement above or under water~ where the pressure conditions are very different, then either a relatively expensi~e pressure gauge wi-th a wide measuring range would have to be usèd~ or provision is conveniently made~ that the measuring range of the pressure sensor can be selected in each ca~e for measurement of air or water pressure with the aid of a switching device4 ~he switching device preferably-includes-~at~least~one ~E~' switch, which is followed by an impedance converter for decoupling with respect to the input of the subsequent stage, especially an analog-digital converter.

~he con~erter device itself conveniently consists of a computer, aæ well as a memo~y or memories for bottom-timest decompression times and~or repetiti~e groups~ which memories Call9 for example~
be tabular memories.

4t the output of the pressure sensor, in particular3 a differentiating stage is connected~ because on the one hand the speed of ascent can be checked; but on the other ha~d it i8 also pos~ible, that the 0~3 switchi.~g device for the changeover from air to water pressure measurement will comprise a step-change detection stage for the pressure~ formed, for example, by the differentiatLng stageO

Other pos~ible for~s of this switching device ~re a manually operated switch (the operation of which could, of course9 be forgotten) or a switch operated by a moisture sensorO ~ut while the latter version could cause switching errors during preparatory showers or on surfacing as a result of residual moisture, reliable switching and indication is guaranteed b~ the step~change detector stage. In this case~ the question of the step-change detector stage could also be solved in other ways than by a differentiating sta~eJ for example with the aid of a threshold switch~ with memory circuits and appropriate comparator stages or the like~

~ut also for other reasons9 eOg~ for an evaluation and logic stage with a limited working range~ range switching~ for example by changing the gain or the bit range of an analog-digital converter connected before the e~aluation and logic stage5 by means o~ a switching de~ice9 can be advantageous. ~hus it is po6sible to use cheapex components~ ~uch as a~ evaluation and logic stage of smaller capacity. ~he switching device can then be formed from -the same equipment~ which also carries out the switching of the pressure sensorO

The possibilities of chang~over switching enumerate~ above ~s examples are indeed quite practicable, but in many cases they are too expensive. -Therefore~ in practice, preference is given to a solution in which a reference voltage source9 switchable by the æwitching device and conveniently followed by an analog-digital converter, i8 providedO

9 ~p~rt from the water pressure, the actual air p~essure i~ also to be included in the calculation~ it is necessa2y to wor~ with a~
i~dicatL~g de~ice with a main switch which can be operated at will9 in~particular manually, because the staxt of operation of the device cannot, indeed~ be detected automaticall~O In this case it is con~enient if, apart from this main switch9 espeeially for switching on the pressure gauge~ in addition to the pressure gauge a second switching device is provided for switching further parts of the equipment when diving in water. ~ere toot the above-mentioned switching de~iee ean take oYer the role of this second switching device, in order to save costs for further components.

On the one hand every automatic device is subject to possible malfunctions; on the other hand not all possible errors of a diver c~n be detected with reasonable expense. In such cases, the indicating device can give incorrect indicationsO But this would entail an additional danger for the diverO Starting from an indieating device with at least one detector circuit for an abnormal function, such as for an incorrect action of -t`he di~er, it is therefore proposed9 that a by-pass eircuit is provided for the converter equipment and that this by-pass eircuit is eapable of being switehed on by the detector eireuit~ while in ease o~
occurrenee of the abnormal function - e.gr even if the main switch is f1rst operated under water~ if the memory eapaeity is exceeded or the like - a warning signal and/or a slave indicator for the maximum di~ing depth reached can be switched on by this by-pass cireuit~ In this wyy it is ensured~ that if the capacit~ is exceeded or in ca~e of another failure of -the normal funetion~ at least that indieation is given, that is obta~nable with known deviees. In this ease it is particularly advantageous7 if in an indieator deviee with at least one segment display, the latter can be switched alternately to indicate various display data, for example to the present decompression depth before oecurrence of the abnormal function and to the maximum diving depth thereafter~ On the one hand thi~ gives a sa~ing on components and on the other hand it 6a~es the di~ex from the overloading of the equipment, which ean only impede work under water and moreover ean make the indication less clear~ and can of eourse even eause dangerous erxorsO

To reduce the current consumption of the indicating device~
which as a rule will be battery-cperated, it i8 convenient if an astable multivibrator circuit is provided for the pulsed activation of at least one display, eOg. ~ith 3 to 4 signals per second~

A further ~ crease in the accuracy of the indication can be achieved, if the circuit comprising the converter equipment also include a memory for the repetitive groups obta~ned through repeated diving with equivalent diving time obtained by means of the converter device~ through any decompression, taking accolmt of the decompression parameters, and t~king account of the times on the surface. In case of repeated dives with a period on the surface in between, a residual saturation with nitrogen of the tissues of the diver can still occur through the previous dive~ if this has not already become zero through an appropriately long stay on the surface. In the latter oase, the texm "Repetitive group zero" is used, which means that the diver can dive without an~ handicapO If, on the other hand~ the repetitive group is not equ~l to zero, then in accordance with the above proposals~ it can go immediately into the calculation on diving a~in~
For this purpose, tabular memories are preferably provided for the repetitive ~roup tables~ which æe themsel~es knowng while tabular memories can also be provided within the converter equipment for the bottom-times and the decompression times. Such tabulax memories simplify the construction. ~rthermore, however~ it is also convenient, if the converter equipment has a memory circuit for the depths dived and elapsed times, as well as for the correction values arising, where applicable.

Fu~ther details ~f the invention are sho~n by means of the following description of embodiments of the invention, which are shown schematically in the drawing.

Figures 1 and 2 show the graphs for various diving operations, ~y means of Figr 39 the significance of the air pressure will be explained~

Figures 4 and 5 show the graphs for ~arious repetitive dives, Fig. 6 is a block circuit diagram, ~n roughly schematic form, of an indicating device in accordance with the in~ention9 of which Fi~. 7 illustrates the Lndications which can be obtained;

Fig~ 8 represents a detail of the timer;

Figure~ 9A9 9B show the circuit of the indioating device in accordance with the invention9 of which Figure 10 illustrates details of the display drive from Figo 9~;

Fi~ure 11 shows the code used in the aboYe~

Figures 12 and 13 represent alternati~es to a circuit detail of ~ig~ 9A;

In Fig. 14, the main program sections for the indicat~g device in accordance with the in~entio~ are explained;

Figo 15 is a ~emo~y occupancy plan, to which Fi~ures 15A to 15D represent the data arrangements;

Figure 16 shows the program structure9 while ~igures 17 and 18 illustrate details of the progra~ sequences.

- 15 ~ 3 Figures lA to 1H show dives of YarioUS kinds. According to the tables which have previously been customary, de pite the differences~ deoompression conditions, which only depend on the maximum depth reached and the total duration, must be adhered to for all dives. Even if, for instance~ only 38 m had been reached in a di~e, it would be necessary to round off to 40 m, because the tables are only graduated in steps of 5 metres.
Exclusivel~ in a dive as shown in ~ig. 1A would the decompression plan of the -tables be fully utilised~ i e. only with a very rapid descent to the maximum depth and remaining there until resurfacing.
<

In the example shown in Fig. 1~ a stop is interposed at 19 m during the ascentO ~ccording to the tables, this does not count as a decompression stop, but must be counted onto the dive time.
~hus the decompression conditions will only be fully utilised in the dive as shown in Fig. lA~ while in the case of ~ig~ 1B~
because of the necessary æafety mar~in for the dive as per Fig. 1A~ decompression would have to be carried on for far too long. ~aturally9 most divers are also well aware of this and they are then tempted to shorten the decompression time found in the table arbitr æ ily.

On this subJeot~ it should be ~entio~ed9 that the complete resurfacing tables of the Pressure Chamber Laboratory of the University of Zurich *~ consist of five æet~ of tables of similar construction, for altit~des abo~e sea level of 0 - 700 m ('~ables 1 tQ 4), 701 - 1500 m ('rables 5 to 8) and also 1501 to 2000 m~
2001 to 2500 m and 2501 to 3200 m, and include, in each case9 a decompression table, a zero-time table~ a surface interYal table and an added-time or repetitive table.

*) Schweizerische mediz~nische Wochenæchrift 103, No~ 10 (1973) - 16 ~

Since the tables are only graded in steps of 5 metres9 let us e~plain a ~ew point6 below on the determination of the "bottom time"~ firstly for the descent phase. Let it be assumed, that the dive in question has not been preceded by any other within the last 12 hours In accordance with the grading of the tables, the "Depth stage" is understood to mean the range from one depth value in the table to the next greater depth value in the table (where the uppermost or first depth etage begins at zero metres), a "repetitive dive" means a repeat dive within 12 hoursg the "surface interval time" means the time at the surface between t~o dives,and the l'present bottom-time~ means that bottom-time, which applies up to the conversion calculation~ ~s long as the di~er i8 in the first (uppermost) depth stage~ the bottomStime i9 equal to the total dive time~ i.e. the time which has elapsed since the begi~ning of the descent, If the diver descends from the first depth stage into the second, it is possible to convert the previous bottom-time into a~
equivalent dive time (bottom-time) corresponding to the second depth stage~ ~aturally, this is only meaningful~ if a gain in bottom-time occurs through this conversion.

l'his conversion calculation method is based on the fact thatQ
in case of a change of depth stage to a greater depth~ the preceding dive is considered as a completed dive, which is now followed by a fuxther dive, with surface time interval zero within the meaning of a repetitive dive.

Thi~ conversion of the bottom~time of one depth stage into the equivalffnt bottom-time of the next greater depth stage can be carried out on each change of depth ~tage from a higher to a deeper depth stage and will be describea as step~by step descentO

The con~ersion itself is carried out by means of the two depth stage~ and the present bottom time in the added time table.

17 ~ $ 0~

Ex~m~les lA to 1H: see Tables 9 and 10 at the end of the description and Figures 1A to 1E.
Diving operations in the range from 0 to 700 m above sea level.

Fig~ 1A shows a dive with repetitive group zero9 as based on -the decompression tables. When surfacing at point e9 after a total dive time of 34 minutes and a maximum depth reached of 33 m, as per ~able 1, one decompression stop of 5 minutes is to be mad~ at 6 m and one of 17 minutes at 3 m ~ig. 1~ shows a dive with repetitive group zero9 in which the ascent takes place step by step - but within the so-called zero-t~me linit. This zero-time limit (Table 2, or~ for 701 to 1500 m above sea level~ Table 6) states those limits of a dive~
up to which a decompression does not have to take place, i.e.
up to which the diver can return to the surface immediately at any time (naturally obserYing the maximum speed of ascent of 10 m/~in). Now~ in this range every pre~ious total dive time can be converted~ on passing through a depth stage, into the e~uivalent dive time of the next depth stage, with the aid of table 4 (or table 8 for 701 to 1500 m above ~ea level)~

The preseut dive time at any point on the dive is equal to the e~uivalent dive time of the previous point plus the time which ha~ actually elapsed since thenO If~ at this point of the dive~
a depth stage is passed in a downward direction - or upwards9 provided the diver is within the zero-time limits ~ this present dive time is con~erted into a new equivalent diYe time~
by first deducting any repetitive added-time included in the value, then converting the rema~ning present diYe time to the new depth stage always rounded up - after which the repetitive additio~
corresponding to this new depth st ge is added on againO ~s long as the diver i~ withi~ the zero-time limit, the conversion is carried out in accordance with the added-time or repetitive table (Tables 4 or 8)~ otherwise in accordance with the decompression table (Ta~les 1 or 5)~

If rounding errors creep in through diving down and up several times9 these will be eliminated by comparison with the conversion to the final dep-th stage, if a shorter equivalent dive time is obtained from this.

In the example of Fig. 1B~ one finds for poin-t b (15 minutes5 33 m)~
in Table 4, rounded up to the table value of 17 minutes at 35 m the equivalent time value of 34 minutes for the ne~ depth stage of 19 m (rounded up to 20 m) The equivalent dive time is thus now 34 minutes at 20 m. Thus the zero-time limit (see Table 2) is exceeded and the specified decompreæsion ~top, as per Table 1, finally amounts to 7 minutes at 3 metresO

The dive as shown in Fig. 1C shows a step-by-step ascent, ~hich however already takes place outside the zero-time limit In this case~ also in accordance with the decompression tables o the Pressure-Chamber Laboratory of the University of Zurich, no equivalence conversion may be carried out, and decompression must take place as though the total dive time had elapsed at the maxi~um depth reached.

Figure lD shows a dive~ again with repetiti~e group zero, in which the descent take~ place step by step~ but within-the zero time. As can be seen from Table 5, each time a depth stage is passed through~ a conversion to an equivalent dive time can take place~ which finally gives a ~ain in dive time totalling 10 minutes, a~ compared with conventional calculation~ and this even gives a gain in decompression time of 13 minutes.
~heoretically, according to the tables of the Pressure-Chamber Laboratory of the University of Zurich, the calculation of the step-by step descent would be permitted~ but this has proved in practice to be far too complicated, whenever use was mad~ of thiE possibility~ Only the indicating device accordLng to the invention has provided the possibility here, of implementing these time gains which are possible according to the tablesO

Finally~ ~igure 1E shows a dive with repetitive group zero~ in which the descent takes place step by step, but outside the zero-time limit. ~he conversion can be carxied out in the iame way as with step-by-step descent within the zero time m e dives of Figures 1A9 1~ ~nd 1C end - as stated in the ~igures - with the diver in repetiti~e group J. ~fter a surface interval time of, for example5 185 minutes at 0 to 700 m above sea level - as can be seen from Table 3 - he is in repetitive group ~. For this finding, the next shorter time listed in the table is to be selected in each case; rounding up or down or interpolation are not permittedO

A dive, in which the diver dives again after such a surface interval time with repetitive group B, is shown in Fig. 1~.
In this case, after 7 minutes and 30 m depth, the repetitive group is applied for the first time to the equivalent dive time and is subsequently carried forward continuouslyO After the dive~
which actually only had a duration of 26 minutes, decompression must take place as though it had had a duratio~ of 34 minutes.

~om dive 1~ (repetitive group J) and a subsequent surface interval of 150 minutes, the di~er i in repetitive group C. As shown in Fig~ 1G~ there then follows a brief descent to 19 m and a subsequent repetitive dive with step-by-step ascent. After the ascent beginning at point a, the conventional method of calculation would give repetitive group D and~ at point c~ a decompression plan for 75 minutes at 20 m depth with a total of 18 ~inutes decompression time at ~ m. Now, after ve~y short dives, the repetitive group re~ains unchanged7 that is, whenever the line for repetitive group A L~ the added-time or repetitive table is not exceeded. ~or 20 metres7 this shows a time of 8 mInUtes~ while the dive in Figo 1G only had a duration of 4 minutes (not counting the ascent time~. At point bg the repetitive group C is taken into account on the di~e time of 9 minutes for the new dive, with an addition of 16 minutes (fxom ~able 4p at 20 m depth). ~ecause the diver is still within the 18 m depth stage at point c, he remains within the zero~time limit~ although for fixing the relevc~nt decompression conditions rounding up to 20 m would occur and therefore~ with 30 minutes~
the zero-time limit would be exceedecl. ~he same applies for point d9 the zero-time limit for the 18 m depth stage (50 minutes) is reached~
but at this time the diver is in the 12 m depth stage~ that is on an equivalent dive time of 113 minutes at 12 m, and has thus not yet exceeded the zero-time limit of 200 minutes for 12 metres.
~he repetitive diverwhich takes place after the short descent and re-ascent in Fig. 1G, proceeds according to the second minutes scale~
marked below the time abscissa.

Finally9 ~ig. 1H shows a di~e, which the diver starts with the repetitive group E, resulting from the previous dive 1C and a surface interval of 110 minutes~ the dive sequence consists of a bnief descent and a ~ubse~uent repetitive dive with alternations of depthO ~he conventional calculation method would give repetitive group F after the ascent beginning at point a and, at point g~ the decompression plan for 72 minutes at 20 m~ i.e. a decompression stop of 18 ~utes at 3 m. With the converter device according to the invention9 however9 the repetitive group E (unchan~ed9 because line ~ o~ tha repetiti~e table (10 minutes at 15 m) has not been exceeded) is taken into account in the calculation of the present or equivalent dive time, once repetitiYe table line A is exceededg by the time addition of ~4 minutes9 A descent into the depth stage of 18 m at point d finally ~ive6 an equivalent dive time of 37 minutes at 20 m9 while the ascent and further descent to points e and f permits two different calculation methods. According to the first, a conversion to depth 8tage 12 ~ is first carTied out~ which would gi~e a~ equivalent dive time of 97 minutes at 12 m for point f Accordi~g to the second~ the correction method, the conYersion can be carried out at point e to depth stage 15 m~ which hae the effect~ that the whole dive ~equence up to point f is o~ly booked at 87 minutes at 15 m, as a result of which the diYer can decompress at point g with only 5 minutes at 3 m9 while according to the first-named method he would have needed 10 minutes and, according to the conventional method 2~ minutes.

~nrough the conversion with the indicating device according to the invention, an equivalent dive time i8 obtained with less æuperfluou safety margin, so that it is worth while for the diver to convert9 if the equi~alent is shorter than the actual dive time. During the ascent the relevant dive time must also be determined in each case, but here the Pressure-Chamber Laboratory prescribes~ that all stops during the ascent (outside the zero-time limit) must be counted onto the dive tlme in their full duration, including the ascent time from the maximum depth reached to the stop~

In the following examples (see Figures 2A to 2G), "30ttom-timel' means the actual or any converted (equi~alent) bottom-time in each case and "Deco" denotes the prescribed decompression condition~.

2 A) Dive with repetitive group G after previous dive lD and subsequent surface interval of 25 minutes ~ the range from O to 700 m above sea level; repetitive dive with step~by-step descent. Conventional calculation method gives~ at point f and for repetitive group G, the decompression plan for 82 min /
85 m; 10 minutes at 6 m and 38 minutes at 3 m.

point ~: Step~by-step descent Conversion of 17 min / 9 m to 12 min / 12 m, sa~ing i~ time 5 minutes.
Point b: Repetiti~e group G is taken into account in th~e bottom time calculation after the repetitive table line A (12 min / 12 ~) is exceeded. ~ottom-time = 13 min + repetitive addition 85 min = ga minutes~

Point c: Step-by step descent taking account of repetitive ~roup Go ~ottom time 108 min/12 m - 85 mln repetiti~e time addition (G) 23 min/12 m Conversion to 15 m depth stage 22 min/15 m ~epetitive addition ~ min/15 m 85 min~l5 m Zero-time limit exceeded (75 min / 15 m) Bottom time 85 min / 15 m - Deco: 3m/5min Poi~t d: Step~by-step descent taking account of repetitive group G.
~ottom-time 87 min/15m - 63 mi~ repetitive time addition (G3 24 min/15m Con~ersion to 20 m depth stage 20 min/20 m Repetitive addition + 44 m m 64 min/20 m ~ottom-time 64 m~n / 20 m - Deco: 3m/18min Point e: Step by-step descent taking account of repetiti~e group G.
~ottom time 71--mi~/20 ~
- 44 mi~ repetitive time addition (G) 27 min/20 m Conversion to 25 m depth stage 26 min/25 m Repetitive time ~ddition + 34 m~=
60 min/25 m Bottom-time 61 min ~ 25 m - Deco: 6m/3mi~
and 3m/30 min 2 ~) Dive at 701 1500 m above ~ea level (see Iables 5 to 8~) after previou di~e 1E and a subseq~lent surface interval o~ 110 minute~ at 0 - 700 m -abovs sea level - there follows repetitive group D ~rom H~
ana then a surface ~nterval of ~0 minutes a-t 701 ~ 1500 m above sea level - there follows repeti-tive group ~ ~rom D~

- 23 ~

In comparieon with this, with a surface interval of 190 minutea at 0 - 700 m above sea level, ~epetitive group ~ would be obtained.
Ihe conventional calculatisn method give , at pQint f and with repetitive group A, the decompression plan fox 54 min / 20 m - Deco: 4 m / 5 min 2 m /19 min Point a: Repetitive group A is taken into account in the bottom~tlme calculation after exceeding the repetitive table line A (12m/13_in)~
~ottom-time = 14 min ~ repetitive time addition + 13 ~1n = 27 min.
Point b: Step-by-step de~cent taking aocount of repetitive group A.
~ottom-time 47 min/12 m - 13 min repetitive time addition (A) , 34 min/12 m Conversion to 15 m depth stage 30 mL~/15 m Repetitive time addition ~ 11 m;n .. ..
41 _inJ-l5 m Zero-time limit exceeded ~30 min/15 m) ~ottom-time 41 min/15 m ~ Deco: 2m~8min Point c: Step-by-~tep de~cent taking account of repetitive group A.
Bottom-time 47 min~15 m - 11 min repetitive time addition (A) 36 min/15 m Con~ersion to 20 m depth ~tage 26 min/20 m Repetitive time ~ddition + 8 min 34 minj20 m ~ottom-time 34 min/20 m - Deco: 4m/3 min and 2 m 9 ~in - 24 ~

- 2 C) Extreme-case dive without previous loadLng, repetitive ~roup Zero, at 0 - 700 m above sea level. Deep dive, which goes beyond the table values - ~Out of range".
Points a - h: Step-by-step descent within the zero-time with maximum time gain of 11 minutes.
ao Conversion 16 min/ 9m to 12 min/12 m: Time gain 4 min b: " 12 min/12m to 10 min/15 m: '~ " 2 min c: " 11 min/15m to 12 min/20 m: " 't 0 min d: "11 min/20m to 9 min/25 m: " " 2 min e: ~9 min/25m to 8 min/30 m- " " 1 min f: "8 min/30m to 6 min/35 m: " " 2 min g: "6 min/35m to 6 min/40 m. " ll 0 min h: "6 min/40m to 5 min/45 m, " " 0 mi n Zero-time limi-t exceeded (0 min/45 m) ~ottom~time 5 min/45 m - DecoO 3 m/4 min Through too slow a descent from point a to h i-t would be quite possible that the maximum time gaïn of 11 minutes would not be reached~ if a bottom-time of 7 minutes or 9 minutes at 45 m occurs~ with a corresponding effect on the decompression plan.

Point i: ~ottom-time 11 min/45 m - Deco: 6 m/2 min and 3 m/6 min~
Point ko ~ottom time 16 min/45 m - Deco: 6 m/3 min and 3 m/11 min~
Point l: Conversion 18min/45m to 16min/50m; 'rime ~ain 2 minutes; ~ottom~time 16min/50m ~ Daco:
6m/5min a~d 3m/17min.
~otal dive time 27 min.

- 25 ~

Point m: Conversion 18 min/50 m to 17 min/55 m, Time gain 1 min, 30ttom-time 17 min/55 m Deco: 12 m/1 min, 9 m/4 min9 6 m/8 min and 3 m/24 min.
Total dive time 42 min 3 Point n: ~ottom time 21 min/55 m - Deco: 12 m/2 min, 9 m/7 min, 6 m/10 min and 3 m/32 min, Total dive time 56 min~

Point o: Conversion 23 min/55 m to 22 min/60 m;
Time gain 1 min. Bottom-time 22 min/60 m -Deco: 15 m/2 min~ 12 m/2 min, 9 m/10 min~
6 m/10 min and 3 m/35 min.
Total dive time 64 min.

Point p: Conversion 24 min/60 m to 23 min/65 m;
Time gain 1 min; Bottom-time 23 min/65 m -Deco 15 m/2 min~ 12 m/4 min, 9 m/10 min9 6 m/13 min and 3 m/40 min9 Total dive time 75 minO

Point q: Bottom-time 26 min/65 m - Deco: 18 m/1 min~
15 m/2 min, 12 m/8 min9 9 m/14 min, 6 m/18 min and 3 m/46 mLn.
~otal di~e time 95 min.

~oint r: ~ottom~time 31 min; depth of dive 65 m; for this point no decompression conditions can be determined - table values exhausted. "Out-of rang~' LED lights up~
decompression conditions and ascent time are erased, maximum depth reached is output.

2 D) Extreme-case dive without previous loading~ repetitive group ~ero at 0 ~ 700 ~ above sea level. Deep dive beyond 70 m, Table values exhaus~ed - "Out of range"~

Points a - f: From point a~ the decompression conditions are continuously increased as each of the depth stages is pasqed through down to point f.
a: ~ottom-time 1 min xx sec - Dkco for 10 min/45 m - 3 m/4 mi~
b: ~otto~-time 1 min ~x sec - Deco for 10 min/50 m - 3 m~5 min c: ~ottom~time 1 min xx sec - Deco for 10 min/55 m - 9 m/1 min 6 m/2 min do ~ottom~time 1 min x~ sec - Deco for 10 min/60 m - 9 m~1 min ~ m/3 min 3 m/5 min e: Bottom~time 1 min xx sec - Deco for 10 min/65 m - 12 m/1 min 9 m/2 min 6 m/3 min 3 m/6 mLn Point f: Bottom-time 2 min xY sec - Deco for 5 min/70 m 9 m/2 min 6-m~4 min 3 m/5 min ~otal dive time 18 mun~
.
point g: Bottom time 6 min xx sec - Deco for 10 min/70 m - 12 m/2 min 9 m/3 min 6 m/4 mln 3 m/6 min ~otal dive time 22 min~

PsLnt h: B~ttom-time 11 min xx sec - Deco for 15 min/70 m - 12 m/2 min 9 m/3 min 6 m/10min 3 m/20min To-tal dive time 42 min.

Point i: Diving beyond the 70 m depth stage ~ "Out of rangen T.hn lights up, æurfacing time and decompression conditions are eraæed~ the ma~imum depth reached is output.

- 27 ~ 3 2 E) Dive with repetitive group zero at mountain lake alti~ude of 701 - 1500 m above sea level (see ~ables 5 -to 8')~
Realistic dive at alternating depthsO

~oint ao Step by-step descent Conversion 15 min/10 m to 13 min/12 m; time gain 2 min.

Point b: Step-by-step descent Conversion 13 min/12 m to 11 min/15 m; time ~ain 1 min.

Point c: Step-by-step descent Conversion 11 min/15 m to 8 min/20 m; time gain 3 min7 Point d: Step-by-step descent Zero-time limit of the 20 m depth stage (15 min/20 m) exceeded.
Conversion 15 min/20 m to 23 min/15 m.

Point e. Step-by-step descent with correction calculation Conversion 25 min/15 m to 21 min/20 m Correction calculation Pottom-time = Bottom-time of the 20 m depth stage at point d plus the time elapsed since point d~
~ottomwtime = 15 min ~ 2 min = 17 min/20 m Zero-time limit (15 min/20 m) exceeded.
~ottom-time 17 min/20 m - Deco. for 20 min/20 m - 2 m/4 minz Point f: ~ottom-time 21 min xx sec ~ Deco. for ~5 min/20 m - 2 m/6 min.

Point g: Step-by-step descent Conversion 25 min/20 m to 20 min/25 m ~ottom-time 20 min/25 m - Deco~ for 25 min/25 m - 4 m/4 min 2 m/8 min - 28 ~

point h Commencement of ascent at 10 m/min Bottom-time 25 min xx sec.

Point i: Lea~ing the ascent cone~ the bottom~time is increased by the time spent in the ascent cone.
Bottom~time 26 min xx sec Deco. for 30 min/25 m - 7 m/3 min 4 m/4 min 2 m/9 min 2 ~ Dive after previous dive 2E ancL a subsequent surface inter~al of 70 minutes at 701 - 1500 m above sea level - this results in repetitive group D from G - and then a surface interYal of 80 minutes at 0 - 700 m above sea level this results in repetitive group ~ from D~

In comparison with this, with a surface interYal of 150 minutes at 701 1500 m above sea le~el~ repetitive group A would be obtained~

At point h9 the conventional calculation method gives the decompression plan for 44 min/40 m, of 12 m/ 2 min 9 m/ 7 mi~
6 m/20 min 3 m/40 m~n, whexe leaving the decompression phase has not ye$ been taken into account.

Point a, Repetitive group A is taken into account in ~he bottom-time calculation after the repetitive table line A ~40 m/4 min) is exceeded.
Bottom time = 5 ~ repetitive time addition 4 min - 9 minO

- 29 ~5~

Point b: Zero-time limit (lO min/40 min) exceeded~
Conversion 10 min/40 m to 10 min/35 mO

Point co Zero-time limit (15 min/35 m) exceededO
Conversion 15 min to 22 min/30 m.
~ottom-time 22 min/30 m - DecoO fox 25 min/30 m - 3 m/5 min.

Point d: Step~by-step descent wi-th correction calculation Conversion 32 min/30 m - 6 min repetitive time addition (A) 26 min/30 m Conversion to 22 min/35 m Repetitive time addition ~ 4 min ~ottom~time 26 min/35 m Correction calculation .. _. . . . . ..._ . .
Bottom-time = ~ottom,time at point c at 35 m plus the time which has elapsed since c~
Po-ttom-time = 15 mi~ + 10 min = 25 ~n/35 m Pottom-time 25 min/35 m - Deco. for 25 mi~/35 m -~ 3 m/9 min~

Point e~ Pottom~time 26 min x~ se~ - Deco for 30 ~ ~ 35m - 3 m~12 min Point f: ~ottom-time 31 min ~x sec - Deco for 35 min/35m - 6 m/5 min 3 m/17 min.

Point ~: ~o-ttom-time 36 mi~ xx sec - Deco for 40 min/35m - 6 m/ 7 min 3 m/20 min.

Point h: Commencement of ascent for decompxession at 10 m/mi~

- 3 ~ 5 ~

Point i: Descent during the decompression phase to more than 3 m below the deepest decompression stage (7 m)~
~ne whole decompression time up to then is added on to the bottom-time.
i.e. Bottom-time = 40 min ~ 5 min decompression time -45 min.
~ottom-time 45 min/35 min - ~eco for 50min/35 m - 9m/ 3min 6m/1Omin ~m/35min Point k: Recommencement of decompression, but no~ for 50 min/~5 m.

2 G) Extreme-case dive without pre~loading. Repetiti~e group ~ero at O - 700 m above sea levelO

1. Dive with emergenc~ return to surface.
2~ Dive7 in which the diving computer is first switched on under water~

1 Point a: Zero-time limit (O min/45 m) exceeded~
Bottom time 2 min xx sec - Deco. fox 10 min/45m - 3m/4min.
Point bs Start of emergency ascent.
Point cs Ent~y into the decompression stage.
~E~O LED lights up.
Point d: Arrival at the surface without including the prescribed decompression stop. "Out-of-range" LED
lights up~ Decompression conditions, surfacing time and Deco LED are cleared~ the ~aximum diving depth reached is output.

5~

21 Point a: Diving computer switched on under waterO
"Out of range" LED lights Up9 m~ximum diving depth reached is output as slave indication.

It is in any case important, that an~ dive~7 who remains above the zero-time cur~e with regard to the dive time and the maximum depth of dive~ i8 in the zero-time diving range and therefore does not ha~e to make any decompression s-tops when surfacing (even though a pause of 3 m;nutes at a depth of ~ m i8 reccmmended when surfaci~g). But as long as the diver is within the ~ero-time~ the method for determination of the equivalent bottom time~ described above for the descent7 can also be transferred to the ascent~ because the di~er can in any case return to the surface at any time without decompression~

~nder these condition67 a~ added time can also be provided from the added time table for the following dive during the ascent (for the purpose of a repetitive di~ing sequence). But now the problem ~rises9 that with general use of this method fox all depth stages and with con~ersion of the actusl bottom~time~ on moving up beyond a depth stage~ into the bottom-time of -the higher depth stage; substanti 1 rounding errors are introduced.
~hese ha~e a particularly ~reat effect~ if the diver first floats ~pwards by a number o~ depth ætages and then dives a~ain to the maximum depth stage. Advantageously9 the solution to this pr~blem consists of the ract, that the preceding dive at a greater depth is only converted to the depth stage of the prese~t diving depth~
if the ac*ual bottom time has just become as great as the ~ero time of the maximum~diving depth~ At the time of conversion of the bottom-time to the act~al diving depth9 it is only necessary to record a correction time and to use the previous bb-ttom~time as the co~rection bottom-time~ ~owever9 these two correction values are only necessary if t`he diver returns to the maxLmum dlving dep-th s-tage again within a hort time~

- 32 - l q ~ 3~

It i8 then necessary to compare whether the sum of the correction bottom-time and the correction base-time recorded at the time of return is less than the actual bottom-time which has elapsed up to this point in time~ If so~ the actual bottom~time must be corrected, by setting it equal to the sum of the correction bottom-time and correctio~ time. Otherwise the conversion has been worth while.

Through this novel method, a significant advantage is obtained, since in this wa~ it i~ possible for a dive to be considered~ both iu the descent and i~ the aæcent to a certain extent, as beIng composed of successive repetitive dive~ in accordance with the tables and thus to provide the necessa~y conditions for digitalisation, So much attention has been paid to the digitalisation of the diving sequence, because the values needed for the determination of the decompression conditions, the bottom-time and the maYimum depth~
can be determined optimally in this way. With the bottom~time and the maximum depth, the associated decompression conditions are read from the decompression table.

~he decompression conditions mean the decompression times of the individual decompression stages of the decompression tables~
times which have to be adhered to by the diver.

~he existing rules are somewhat different for the case where a dive iB preoeded by another dive within 12 hours. As has already been e~plained by means of the conversion examples aboveg evexy dive i~ assigned a repetitive group at the béginnirlg of the surface inter~al9 corresponding to the degree of nitrogen saturation in the tissues of the diver~ in oxder to detexmine an appropriate added value for the decompresæion parameteræ~ Con~entionally~ the repetiti~e ~roup for the end of the surface intexval is determined at the beginning of the repetitive diveO

- 33 ~

However~ it is advantageous, if in contrast to this conventlonal method, the repetitive @oup is continuously tracked during the surface interval, in order to shorten the surface interval table needed for this purpose and thus, after all, to save memory locations for the indicating device according to the invention.
Ihe resultp i.e. the repetitive group obtained at the end of the surface interval, is the same~ The continuous deter~ination of the repetitive group will be described later with the explanation of the pro @ am se~uences, Usually~ the repetitive group is only taken into account at the beginning of the ascent~ because on inspectin~ the table~ the conversion of the bottom-time had to be carried outD taking acco~nt of the repetitive @ oup in each case. ~ut if 7 as in accordance with the invention, an appropriate converter device is provided, the corresponding correction can easily be carried out automatically~

qherefore it i8 convenient~ if the repetitive group at the end of the surface interval ls taken into account by ~ repetitive time-addition at every change of depth stage during the descent.
~hus it becomes possible to inform the diver at any time of the minimum ascent time including decompression time~ With the conventional methods, the decompression times increase suddenly at the beginning of the ascentS i.e. the correction would be significantly more complicated~ because in the deter~ination of bottom-time (in accordance with the explanations above)~ co~rections already have to be made anyhow and an additional correction value only leads to additional complications.

So if the bottom-time is to be converted during the descent9 taking account of the repetitive group~ then before the conversion of the actual into the e~uivalent bottom time, the repetitive added-value from the preYious change of depth ætage is subtracted from the actual bottom~time, then the conversion is carried out - 34 ~

in the way described above and finally the repetitive time addition of the next deeper depth stage is added on to the actual bottom-timeO
Thus the precedLng dive and the pre-loading of the tissues which it causes is superimposed on the values of the di~e at each change of depth stage to a greater depth~ ~s described above~ these values can already be present in digitalised formO

With the aid of Fig~ 3~ let us now explain the problems which occur in connection with taking account of the air pressure.
Assuming the temperature is the same at the various altitudes, the air pressure decreases with increasing altitude, in accordance with an exponential function.In an exact calculation of the air pressure, account must be taken of the fact~ that the temperature decreases with altitude. In order to obtain as exact a picture as possible of the atmospheric pressure up to an alti~ude of 4000 m~
this is calculated in accord nce with the international altitude formula, which takes account of an annusl average temperature of 15 C at sea level and an annual a~erage atmospheric pressure9 at sea level9 of P0 = 101.325 kPa. It is valid up to an altitude of 11 000 m and reads Ph = 1-013 bar ~ 88000~( ~ 3 In order to obtain as realistic a picture as possible of the air pressure curveD the meteorologic~l variations in air pressure~
which occur as a result of udden changes in the weather and can amount to ~ 50 mbars at sea level, must be taken in-to accountO
That is a relative error of 5%7 which is superimposed o~ the air-pressure curve as a scatter range.

The air-pressure curve shown ln Fig. 3 is approximated by means of a straight line 4 through the points (0/1) and ~3300/0.67)9 while ~ L is the maxLmum air-pressure variation at sea level and S is the range of scatter of the air-pressure variations9 a~ounting ~ 35 -to about 5%. Also shown are the altimeter resolution A per 100 m~
the maximum error FM of the altimeter, ~nd ~1so the mini~um error ~Smin and the maximum error F~na of the altitude measured through the atmospheric pressure~ which can lead, in the transition range from one altitude stage to another~ to the selection of the ne~t set of tableæ.

~his showæ that the 5~ relative error of the air pressure entails a significantly greater relative error with regard to the altitude.

~hen considering the individual altitude ætage boundaries (700/701, 1500/1501 etc.) the relative error rises at the maximum to ~ 72~
~ 500 m on 700 m) and remains at the minimum above 10~ (+~50 m on 3200 m).

Ihese enormous deviations of the cartographic altitude above sea level from the atmospheric pressure-altitude are taksn into account with safety factors in the sets of tables of the Pressure-Chamber Laboratory of the University of Zurich9 80 that the diver is not endangered.

a~
~ccordin~ to the map~ a diver iB on a mountain lake at 1300 m above sea level and uses the set of tables for the altitude stage (700/1500~ m abo~e sea level for his dive. ~owever, as a result of a sudden change in the weather~ the prevailing atmospheric pressure can have risen 90 far, that it now corresponds to an equivalent altitude of less than 700 m above sea level. Now the diver could use the set of tables for the alti-tude stage 0-700 m above sea le~el, if he were to use an altLmeter instead of the map for selecting the set of tables.

In order to attain a g~eater accuracy for the selection of the set of tables than with the aid of a map~ no precision altimeter is needed. The relati~e error of this altimeter o~ly has to be less~

- 36 ~ R~

than the minimum relative error of the cartographic altitude9 related to the altitude equivalent to the air pressure~ ~h~
the relative error of the altimeter only needs to be less than 10~. The indicating device according to the invention takes account of the atmospheric pressure in an adequate manner and therefore refers correctlyt under the conditions of the example stated, to the set of tables for P - 700 m above sea level, which co~responds to the prevailing atmcspheric pressure9 although the diver is at 1300 m above sea level.

Cn the other hand~ the head of water applies for the pressure (Pw):
) Pw g ~2 . g ~ h h ... ~ead of water g ~.. 10 m/s2 (acceleration due to gravity) 9 H20 ... Density of water Assuming (Pw) = bar and ~ H20 = 103 kg/m3, then:
(2) Depth in metres 10 . Pw ~ecause the depth of water cannot ~e determined independently of the prevailing ~tmospheric pressure (Ph), the latter must be taken into account~ ~he ~ater pressure (Pw) is the difference between the absolute pressure (P~bS~ and the air pressure (Ph~.
Therefore the following applies for the depth in metres and the pressures (PabS), (Ph) in bars (3) DEP~ = 10 . (PabS ~ Ph) In order to determine the depth during dives at various altitudes above sea level9 an absolute-pressure sensor must be selected and the depth must be calculated In accordance with (3).

T'he density o~ sea-water is appr m. ~ = 1.025 g/cm3~ that of fresh water approxu~ = 1.0 g/cm3.

~ecause the diving depth must be determined both in sea water and in fresh water, there now follows a brief error analysis.

~L~8~ 3 If, at an actual depth of 10 m~ the depth is determined in accordance with (3)~ taking account of ~ , then 10 m is obtained as the depth in fresh water and 10.25 m in sea water. '~he relatlve error o~ the depth in sea water, related to the actual depth~ is thus 2~5 %.
'nhis accuracy is adeguate, moreover the error lies on the safe side and too small a depth will never be determined through it.

qhus the specific requirements are obtained for a pressure measuring system~ as it will be used in a preferred embodiment of the indicating device described later, namely for an absolute-value pressure sensor from 0 - 10 bars, so that the altitude r~lge 0 - 4000 m above sea level and the water depth range 0 - 80 m can be coveredO

In order to be able to guarantee a sufficiently great accuracy of the altitude measurement and the depth measurement, the relative error must not exceed 3O5 ~

'rhe sensitivi~y ( E ~ bV ) must be so ~reat, that a pressure change of 0.01 bar = 100 m colllmn of air ~ 10 cm column of water gives a voltage change~ which9 after amplification and analog/di~ital conversion~
corresponds digitally to at least one digit of the least significant place; expressed as a binary value (E)2 ~ 2~

It has alread~ been mentioned9 that repeat dives within 12 hours must be taken into account in the determination of the decompression parameters. ~his subject will be dealt with somewhat more precisely below. It has also already been said, that the various repetltive groups are designated b~v letters and lead to an added time according to the added time table.
., Figure 4 ~hows the graphic representation of a repeat dive with a diving time T2 after a previou~ dive with a dive time ~1 and a decompression time D, and after a surface interval Oio ~or example~

the diving time T1 is 50 minutes and the decompression time D9 based on this diving time and the depth (10 m) is 3 minutes~
with which, after surfacing and at the beginning of the surface interval a rep~titive group F i8 obtained. As shown in Fig. 4, the surface interval Oi amounts to 100 minutes. ~uring this time9 the excess gas content in the body of the diver decreases and a repetitive group C9 correspondin~ to a smaller quantity of gas, is arrived at~
This can be seen from the surface interval table. The diver~ who is now in repetitive group C9 wishes to dive to 30 m. In the C-line of the added-time table and in the 30 m column, he finds the added time of 10 minutesc This means~ that there is still as much gas in the body of the diver9 as if he had already been at 30 m for 10 minutes~
Thus9 for the determination of a reasonable decompression~ the added time must now be added on to the new, actual diving time. If9 for e~ample7 the actual diving time is now 20 minutes9 he must select the decompression plan for 30 minutes at 30 m~

Now, a repeat dive as shown in Figure 4, with constant altitude~
is certainly the most common case. ~ut~ with the aid of Figo5, let us discuss what happens if the di~er changes the bod~ of water and the altitude~

At a greater altitude, the times, with which a given repetitive group is reached, are shorter. It is permitted~ to calculate the surface interval at an altitude with a lower set of tables, but -the converse is not permissible~

le ~C~
1st dive at 450 m above sea level, 40 minutes at 30 m; after the specified decompression under water,the diver is out of the water at 11901 hours and is now in Group J. With a helicopter, he is now lown to a mountain lake at 1400 m aboYe sea level9 At 12 o'clock he has risen above the altitude limit of 700 m above sea level.
At this time, he i9 in Group G, which per~its him a fli~ht altitude up to 2000 m above sea level. At 12.55, he is ready for the new dive.

~ 39 ~ a~

According to the surface-interval table for 0 - 700 m above sea level, from 12.06 he was in group F. ~e takes account of the remaining 49 minutes of surface~interval time in the set of tables for 701 - 1500 m above sea level and passes9 at 12.55, from group F to group D. ~e now looks up the added time, according to his new diving depth. At 13.30 the dive is finished and he is now in group G~ At 15.10, he goes below the 700 metre altitude limit.
In the set of tables for 701 - 1500 m above sea level9 he was in group C after a surface interval of gO m;nutes (i.e. at 15.00).
m e further surface interval after 15.00 hours is taken into account in the set of tables for 0 - 700 m above sea level~ since the surface-interval table for 701 - 1500 m above sea level is no lon~er valid a~ter going below the limit of 700 m above sea level.

Construction of the indicatin3 device according to the invention:

The statements above show that the handling of the tables is relatively complicated and it is therefore impossible~ with them~
to ~ive the diver that information, which he would actually need at any time during a dive. me diving computers previously known haYe only automated the reading of the tables, without at the same time makin~ it possible to convert the actual to the equivalent bottom~time, to take account of the actual atmospheric pressure (which, as shown in Fig. 3, can be subject to considerable variation~
or of the repetitive time additions, or to give a continuous indication of the necessary ascent time~ Thus, all in all, the data obtainable from them was subject to great inaccuracies. The object of the invention is to remedy this state of a~fairs and to give the diver the most accurate information possible, especially with regard to the decompression parameters.

Fig~ 6 shows an embodiment of the invention, by means of which this object can be achieved. In this~ $he ambient pressure (i.er both air ~nd water pressure) is fed as an input variable to a converter - 40 ~

equip~ent 5 from at least one pressure sensor 6. A f~ther input variable is supplied by a timer 7~ which - as will be seen from the description which follows - can also be integra-ted into the converter eguipment. Finally~ a power supply circuit 8~ which can be switched on through a main switch 9~ which in turn can be actuated as desired, i.e. by direct manual action or through a remote control, must be provided.

Within the converter equipment 5, not only are the beginning and end of a diving operation, together with the course of its progress9 recorded~ but preferably also the previolls hiætory9 in order to be able to take account of repetitive time additionæ. For this purpose it is, of course, necessary9 that the converter equipment 5 itself, and/or memory devices connected to it, have the associated table data stored in them, Conveniently, the processing of the signals is carried out in digital fo~m~ wherefore it will be necessary~ at least for the pressure sensor 69 which delivers analog signals, to provide an analog~digital converter within the converter equipment As output variables from such a converter equipment 5, a guide-line value At for the ascent time to be expected (including decompressio~
time)~ the decompression p æ ameters D (i.e. depth sta~es and times for decompression), the depth data ~m (such as actual depth and maximum depth)9 and the total dive time Tt can be determined~
Fkrthermore9 however, it iæ ~180 convenientp if abnormal functions are indicated, i.e. incorrect behaviour of the diver and/or of the indicatir4g device itself~ Thus an indication Va can be provided if the diver exceeds the maximum ascent rate, and at least one further indication An, which deli~ers a battery-monitorLng signal in case of iuadequate power supply and/or delivers a signal, if ~alues9 which are not present in the stored tables, occur, for instance because the diver, in contravention of the rules, has exceeded the maximum dep-th of 70 mO

- 41 ~

Although the indicating device must, of course, be housed in a pressure tight case~ a leakage detector, with a corresponding indication, can also be provided. ~urthermore, although the indicating device must be securely attachable to the body of the diver~ con~eniently to the arm~ nevertheless, ~or the eventuality of its loss (for instance, if tak0n off, because the device i~pedes work unde~ water~, it can include a motion detector~ which, in the absence of a movement caused by the diver, will in a short time activate an optical~ acoustic or otherwise locatable signal to facilitate finding the device agaL~.

If the indication An operates to indicate the fact, that the end of a table has been reached, the decompression parameters (outpui variables D) can no longer be determined exactly~ It will be explained later~ that for this event a by-pass to the act~al sonverter equipment can be provided9 by means of which the actual depth and dive time remain indicated to the diver, but the decompression conditions and the ascent time are cancelled, because the latter can no longer be computed, as a result of abnormal behaviour of the diverO For example? in case of an emergency ascent with~ut adhering to the prescribed decompression stops9 in order not to leave the diver completely without information1 the maximNm depth reached can also--be-indicated, so that he can determine a decompression plan for himself~ b~v improvisationf with the aid of the dive ti~e and the m~ximum depth reached.

~hus, all in all, an embodiment of the indicating device according to the invention i8 SO designed~ that the diver only has to switch it on by means of the main switch 9 - before entering the waterl -or off. After that9 the equipment works fully automatically and its operation is reduced to observing the display~ ~he diver will appreciate this simplicity of handling~ because the concentration c~pability of the diver is reduced by narcosis with increased depth and hi~ state of confusion increases. In extreme cases~ this narcosiæ can degenerate into the so-called "ecstasy of the deep which has P-ready ~pelt the doom of many divers~ This increases ~ 42 ~8~

the importance of a clearly legible and understandable display, ~n which only those values, which the diver really needs, are indicated.

S mce every fully-equipped diver often has to carry numerouæ
instruments with hlm, it is advantageous9 if the indicating device according to the invention also takes over the function of other instr~ments. Thus it can easily replace the conventional depth gauge and diverls watch. ln the same way9 it ha8 to ~ldertake the function of an altimeter with a resolution of at least 100 m.
Furthermore~ in order to be able to compute the ascent conditions9 the equipment ~ust detect, by software means, whether the diver:
- is o~ land or in the water~
is floating on the water surfaceg - i8 diving dow~
- is ascending in accordance with the rules, - i5 ascending faster than 10 m/min~
- is ascending too 810wly~
- is diving with ox without pre-loading from previous diYes9 - has exceeded the values of the table to be processed, - has exceeded the ~ero-time limit~
- ha8 to decompress, - has commenced decompression~
- has completed decompression in the specified manner, - is terminating decompression contrary to specification;
- has switched on the indicating device - before entering the water.

If a time-of~day clock is also included in the indicating device, the duration of operability of the indicating device must also last for several days Otherwise the time-of day clock would not bs worth while. Furthe~more~ if a time-of-day clock is included, the operation is no longer limited to ~witching the device on and off~ because this cloc~ can also be set and mnst provide an independent facility for the diver to r~ad the time of day.

~ 43 ~

~igure 7 shows the display panel of a practical embodiment of the indicating device according to the invention~ ~s already stated, the display must provide various indications in different operating states. The most important operating states are "Decocompute" (the normal case) and "Out of Range"~
Further operating states are subordi~ated to these mai~ operating states:
1. M~ximum ascent rate exceeded ("Ascent-Rate"~
2. Countdown for the decompression stops ("Decompression Countdown'9 only subord'nate to "Decocompute").
3. Power~Down 4. Software ErTor.

In one practical embodiment, the display is produced with four 4 digit LCD numerical display units 13-16 and with three L~n indicators 10~12.

LCD displays are indeel more ad~dntageous because of the;r lower power consumption and their good legibility with diffused and focussed incident light, but LED indicator devices must be selected for the most important indications, because at maximum depth~ and especially in darkness, LCD displays can only be read with great difficulty or not at allO In order to save current with the LED indicators9 these can be operated in a pulsed mode if desired. For example9 theoretically, activation through an astable multivibrator with a mark-space ratio of 1 : 1 would already save 5G~ of the energy needed, but in some circumstances a smaller On-Off ratio e~g~ 1:2 or 1:3~ may be adequate. If desired9 a changeover switch can be provided, whereby the LED indicators or some of them only can be switched optionally from conti~uous to pulsed spexationO Also~ a vaxiable resistor may be provided in the circuit of the astable multivibrator, to vary the mark~space ratio. The settin~ control for thiæ variable resistor i~ then - 44 ~

conveniently combined with the control for the above-mentioned changeover switch9 to form a single control.

In the embodiment shown in Fig~ 77 three LED indicators 10, 119 12 are provided, with the following functions:

The light-emittLng diode 10 li~ts UPt whenever the maximum permissible ascent rate of 10 m/min is exceeded.

The light-emitting diode 11 is used to indicate -that the counting of the decompression time has commenced. It lights up as soon as the deepest decompression depth stage for a given dive has been reached, and goes out at the end of decompression~
irrespective of whether this has been terminated in accordance with or contrary to the specification. If need be9 improper behaviour of the diver can be indicated by a flashing signal from this light-emitting diode 11~

The light-emitting diode 12 indicates if the end of the stored tables is exceeded for an~ reason or if the indicating device depaxts from its normal function for any other reason. Ihis light-emitting diode 12 can then only be extinguished again, by turning off the main switch briefly at the surface of the water.

It can be seen from Figure 7, that as well as the LED indicators 109 11 and 12, liquid crystal displays (LCDs) 13 to 16, of four digits in each case, are also provided. They serve to indicate numerical values and are formed as segment displays.

It has already been stated, that the main operating states are designated by the names "Decocompute" and "Out of Range"gwhile in the latter case the light-emitting diode 12 lights upO This indicates that the function of at least the display 16a has been changed hy means of a changeo~er device, i.e. that the liquid crystal display 16 has been connected by switching to another signal source9 - 45 ~ 35~

which possibility has been made visible in Fig. 7, by the fact that the left-hand field o`f display 16 bears the inscriptions DEDEK and DEMAXD. In this way, one display is saved, which means an advantage both in cost and in space.

"Decocompute" i8 the name for the state of the indicating equipmentD as long as it can and may work in accordance with the stored ta~le values and their processing specification~
i.e~

- if the diver ha~ switched on the indicating device out of the w~ter (before the diver enters the water);

- if the diver does not return to the surface, before he has completely decompressed in accordance with the indicated decompression conditions;

- as long as the dive does not exceed the maxi~um values of the stored tables; and - as long as the indicating device does not run into a software errorO

~uring the "Decocompute" operating ætate~ the following values are to be displayed:

Ihe total dive time~ whioh extends from the start of the de~cent until the surface region is reached, in minutes:
DIVE~ in field 13.

~he present diving depth~ to an accuracy of half a metre:
DEP~H in field 14.

~ 5 3 - The ascent time (including the prescribed decompression time in each case) in minutes: ~PDIVT (in field 15)7 which the diver must expect at any time in the dive, if he ascends at the maximum permissible ascent rate.
- The present decompression stage in each case, that isg during the dive the deepeæt decompression depth in each case and, during decompression, the depth at which decompression now has to be carried out, to an accuracy of one metre: DEDEK in field 16a.

- The present decompression time in minutes: DEKOT in field 16bo This is the prescribed decompression time in each case at -the decompression depth stage DEDEK.

These indications can be seen in Fig. 7~ while at the same time the light-emitting diode 12 remains extinguished and the two light-emitting diodes 11 and 10 only light up if the corresponding events occur.

In the main operating state "Out of Range'l, the converter e~uipment 5 (see Fig. 6) i8 bridged b~ ~ by-pass circuit (conveniently provided within a single integrated circuit), ~o that the indicating~device now only perfo~ms the function of a depth gaug~ with slave indicator and a dive timer. The ~'out of Range" indicating mode comes into effect~ as soon as the indicating device can no longer work in accordance with the stored table values and their processing specification~

In the ~Out o~ ~an~e" operating state the decompression times, the decompression depths and the ascent time are no longer determined and the values UPDIV~, DEDEK and DEKOT displzyed up to then are clearedO Inste~d of DEDEK~ the maximum depth reached so far in the di~e, ~EMAXD, which was previously stored without being displayed, is now displayed in field 16a.

As has been mentioned~ a changeover device, provided in the indicating equipment and conveniently included in the integrated circuit, is used for this purpose. If, by chance, the light-emitting diode 11 should have lit up at the time of entry into this main operating state, it is extinguished during this state, just as the displays 15 and 16 b are cleared. Only the light~emitting diode 12 lights up continuously, in order to indicate the cha~ged operating state, while on the other ha~d the light emittiryg diode 10 continues to fulfil its normal function~

~s well as these main operating states9 four further operatiug states were mentioned above. Of these, it has already been explained, that in the "Ascent Rate" state~ i.e. if the maximum permissible ascent rate is exceeded, the diode 10 lights up and that~ with the commencement of the "Decompression-Countdown" state, i,e~
with the commencement of counting of the decompression time from the -time the deepest decompression s-tage is reached in each case, the diode 11 lights up~

The third operating state mentioned, "Power Down" is an operating ~tate, in which the indicating device has to çall attention to the fact that the battery voltage has fallen to a critical value.
In practice~ this can be done by makin~-the-LCD display(s) of - -the effective main operating state flash, e.g. at 0 5 second intervals~ as soon as the batte~y voltage has fallen below a value which is sufficient for the next two hours. As already explained9 current is saYed by driving the displays through an astable multivibrator, which is important in this particular operatin~ state~

~he fourth operating state mentioned9 "Software Error"~is the condition in which an error occurs for reasons c~nnected ~ith the program. ~his pre-supposes9 that the programs are appropriately compiled for the indicating device i.e5 in practice the programs are so constructed, that the indicating device can itself detect 48 ~-an error in the chronological sequence of the pro~rams and thus switches the display orer to the "Software Error" state.
From that time on, all functions of the indicating de~ice are inoperative. Only an E appears in the first digit of the display field for the dive time, to indicate an Error. ~he LEDs are all extinguished.

The embodiment of the invention was based on the considera-tions summarised below.

In order to work with the tables~ the computer needs the data of the dive~ substantially the depth and the time. The depth is determined from the water pressure~ the time is kept in an internal clock~

In a display~ it must be possible to indicate the calculated data and any error indications to the diver.

It must be possible for the diver to switch -the deYice on and off and -to reset it to its initi~l state. If provision is made for operatio~ of a time-of-day clock~ he must be able to input -the time of da~ and~ possibl~ to switch the display mode to indication of the time of day.

In the design of the indicating device which is necessa~y to achieve these objectives, account must be taken ~f the factg that the equipment is to be batte~y-operated, i.eO an operating voltage of approxO 5 - 8 Y i8 available; any voltage above this or with a different polarity must be generated, with the corresponding expense, from the battery voltage; in order to avoid too rapid a discharge of the battery, the circuit must be so designed~ that it consumes as little power as possible. The battexy voltage is to be monitored ana if it falls below a certain minimum value~
this is to be indicated; in order to avoid changing batteries - 49 ~

in the water- ~nd pressure-tight case, it is conYenient to ~e a rechargeable storage batte~y.

~he device should be installed i~ a case which is pressure-tight to a depth of 100 m of water, i.e. external connections, such as the charging connection f~r the battery~ switch spindles etc.~
represent a great mechanical expense and should be reduced to a minimum.

The heart of the converter equipment 5 is a microprocessor 27~
which among other functions - when occupied by a program - wor~s as a computer and will therefore mostly be referred to below as the computer. ~or one embodi~ent of the indicating device according to the invention, a single-chip computer 8748 from Intel i5 used.
~his contains 1k EPROM and 64 R~M locations (including general registers and stack), i.e. space for 64 ~ariablesO If the stack and general registers are disregarded~ there ~till remain approx.
45 variables for use as desired. 1k is available for the tables and the program. The ROM and RAM areas can be extended with additional modules.

~n estimate of the si~e of the tables shows that 3k of additional mem~ry (ROM) will be needed for the tables~

The selected computer has an internal timer/counter~ which runs in p~rallel with and independently of the program. ~his timer/
counter is needed, in order to incre~ent all time counter~ in the program and in order to ~ynchronise the program with the cloc~ time. The main program can communicate with the timer/
counter in the following ways:
Setting the timer/counter - Interrogation of the timer/counter ~ Starting the timer/counter - Stopping the timer/counter - Interrogation of a timer flag, which indicates a timer overf10w.

- 50 ~

m e timer can also intervene directly in the running program through an interrupt ("Timer interrupt")(on any timer overflow).

Depending on whether a mere counter or a timer is needed~ then as represented in Figo 8~ the input r~ 1 or -the computer clock pulse (divided by 32 by means of a divider stage 23) can be switched to the timer/counter. ~or this purpose9 let a changeover switch be connected, symbolically, to one of two terminals 18~ 1 or a stop terminal 20. ~rom the block circuit diagram in ~ig. 8 the most important instructions and -their erfects can also be seen~

In order to start the main program at 0O5 second intervals, the timer/countex will be connec-ted as an inte~rupt-timeri As a result of this~ the quar~tz oscillator frequency must be determined for thP computer clock pt~se and a timer-interrupt program (HT~) must be written.

~s the quartz oscillator frequency, 6 MEz i9 selected~ The cycle frequency of the computer is 15 times less than the qt~rtz frequency7 that is 400 kHz. Every 32 machine cycles~ that is every 80/us~ the interrupt timer is incremented by lo The interrupt timer is an 8-bit register~ ~y the controlled ~etting of this register~ ti~es between 80/u8 and 256 2 80/us = 20.48 ms can be produced~ ~hese times are too short for the intended application and must be extsnded by an auxiliary timer program~ which generates the 0.5 s timing pulse from 25 timer interrupts.

Since the timer-interTupt transfers control approximatel~ every 20 ms from some point in the main program to the auxilia~y timer program, the au~iliary timer program should need as few registers as possible~ since these can no longer be used by the main program.

- 51 ~ O ~ 3 At least one register must be reserved either as the auxilia~y timer or as the pointer to the au~iliary timer~ A programl which as far as possible only needs one register for the auxilia~y timer and for setting the interrupt timer~ is to be aimed at9 In order to obtain as simple an auxiliary timer program as possible, the interrupt timer is allowed to run full several times and is initialised with a correction ralue each time bef`ore the branch into the main program (for the first pass).

De-ter~ination of the corre ~ timer -~ Time interval of 24 "normal" timer interrupts: 20.4 ms - Time for 24 timer interrupts: 24 x 20.48 ms = 491.52 ms - Time difference to the half second: 500 -- 491.52 = 8~48 ms - Number of timer interruptæ needed: 8.48 ms/80/us = 106 - In order to obtain a timer overflow~ which initiates the interrupt9 at the desired time7 the interrupt timer must be initialised at 256 - 106 = 150. The auxiliary timer program HTIME~ mentioned abo~e, will be dealt with later in the description of the programæ. In an~ case, it can be seen from the abore, how the timer 71 described by means of Fig. 6, can be constructed in a practical realisation.~

Since the power supply unit 8 (Fig. 63 can be of conventional construction, it will not be dealt with in further detail and instead~ the input of the third input value9 namely that from the pressure senaor 6~ and the remaining circuit will be illustr~ted with the aid of Figures 9A and 9~.

Some requirements for the pressure sensor have ~1ready been ~stated above. Moreovex, this must be resistant to fresh and sal-t water9 mn~st deliver an electrical output signal for further processing and shall also ha~e small dimensions and be inexpensive.

- 52 ~

The most widely-used systems for electrical pres~ure measurement are load cells with adhesive-bonded strain gauges and pieæoresistiYe sensors. For the indicating device according to the invention9 a piezoresistive system has been selected, because this has the following ~dvantages as compared with those with strain gauges~

_ It delivers a &reater output signal and therefore only requires a simpler amplifier circuit, or none at all~

It is then also less sensitive to interference signals such as thermoelectric voltages etc.

- Ihe single-crystal material with resistors diffu~ed in is not adhesive-bonded as with strain gauges and thus has much less hysteresis (no creep of the adhesive) and no fatigue phenomena (as long as the cell is op0rated within its nominal ran~e).

- M~nufacture in accordance with the laws of semi-conductor physics is simpler and permits large-batch production at much cheaper prices.

~he pressure sensor selected also has the advantages of a pressure range from 0 to 10 bar a~d thus a measuring range-to 90 m depth --~ -- ~
of water~ and is located in a robust steel case, while the external pressure acts on a steel diaphragm which is resistant to salt water.

Ihe continuous signal from the pressure sensor 6~ amplified by means of a~ amplifier 21~ is conveniently to be converted into a computer-compatible, quantized signal, fox which purpose ~n analog-digital converter 22 is provided9 to recei~e the amplified output ~ignal o~ the pressure ~ensor 6. An analog-digital converter with 8-bit resolution is used~ because the computer can only process 8 bits in parallel. In order to be able to measure sufficiently accurately with 8-bit re601ution at the zero point9 for measuring the altitude - 5~ 3 above sea level~ it must be possible to ch~nge the measuring xange~ Thi9 iS possible in the following ways:

- ~y switching the gain of the input amplifier (differential amplifier) 21 as shown in ~ig. 9A;
by switching the reference voltage source ~9 of the analog-digital converter 22 as shown in Fig~ 9A;
- by connecting an analog-digital converter of higher resolution~
so that depending on the resolution needed~ either the upper or the lower eight bits are switched onto the bus.

To supply the pressure senæor 6~ basically, a precise current source would be needed a~d also an accurate reference voltage source would be necessary. However~ both ~tabilised sources can be dispensed with if it is recognised that the pressure sensor with the reference voltage source 24 practically forms a resistance bridge9 which can be connected, in the well-known way~ directly to the ope-rating voltage, while the reference voltage of the referenoe voltage source 24 is also connected, with a simple resistance voltage divider to the operating voltage~ the effects of which thus cancel each other out9 while the signal obtained at the ou-tput of the analog-digital converter 22 is exactly proportional to that of the pressure sensor 6 and thus to the depth of waterO

In order to save stabilised referenoe sources, the pressure sensor is connected directly to the 5 V operating voltage (instead of to 14 V). Through this~ the output sign~l of the pressure sensor fallsO This signal is too small for the analog-digit~l converter 22 and must thus be amplified approximately by a factor of 12~ so that it lies between O and 4 V. The amplifier 21 must then be so designed~ that one can manage with an operating volta~e of only 5 V~ and that the amplifier 21 itself can follow a small input signal to zeroO (Normal operational amplifiers mostly need a supply of ~ and ~ 15 V~ and the output signal only comes to within approx. 2 Y of the suppl~ volta~e)c For this amplifier9 a d;fferential ~ 54 -amplifier 21 was selected, and this will be diRcussed further at a later stage.

Of the further circuit parts which can be seen in Figures 9~
and 9~9 a comparator stage 41 a~ter the differentiating stage 26g the purpose of which will be discussed later~ should be mentioned, and above ~ll the computer 27, which together with a memory stage 28 (EPROM) forms the core of the converter equipment for conversion and selection of the actual or equivalent bottom-time~ taking account of the other parameters mentioned. ~etween the memory 2B and the converter 27~ an intermediate memory (latch) is also connected for addressing the memory 28.

~hus~ the following peripheral components are pro~ided for the computer 27:

A table and program memoIy, both in memory stage 28 An intermediate memory (latch) 29 ~he analog/digital convexter 22 qhe liquid crystal displays 13 to 16 ~he li~ht-emitting diode indicators 10 to 12 If a time-of-d~y display is required, two further switches ~3 and S4~

~o drive these components9 the computer 27 has:

- an 8-bit bidirectional data bus 42, - 2 latched I/O ports~ each of 8 bits~
- 2 test inputs TO and T1 (one of which~ with appropriate programming~
could serve a~ input for the counter and the other a~ timin~ pulse output), - an interrupt input 38.

~ 55 In order to utilise the computer fully and to manage with as few additional components (latches, drivers etc~) as possible, all input and output lines will be used~ as ~ollows.

'~he d ta bus will be used for data transfer from the memo~y 28 or from the analog/digital converter 22 to the computer. In order not to activate both components simultaneously, the correct module must be selected with a control signal (control line:
Port 2, bit 4).

Port P1 is used to dri~e the display~ with the following __ bit allocation:
Bit ~ Digit address (binary~
2 ~
3 ~ Chip address (binary) 4 ~
6 ~ Data (1 figure)

7 ) The binary chip address iB co.nverted in a 1-from 4 decoder 36 into the chip-enable signals, Since the data ~re only accepted by the 1CD-decoder-driver with each positive edge of the chip-enable signal~ this signal must not be present continuously.
For this reason, the 1-from-4 decoder is pulsed with the AIE
signal. (The ALE signal appears once during each computer cycle.) Port P2 is used for page-addressing the memory, for selection between analog/digit~l conYerter 22 and memory 28 and for activating the LEDs ~10-12).

~it allocation:

Bit O ?
2 } Page address for data access in the external memory 4 ~ank switchingg an21og/digit~l con~erter 22 - l~emo~y 28 LED "Decompression Countdown"
6 Pressure sensor range selection 7 LED "Out of Range"

The TF~s 10-12 are activated through a step-detector and driver sta~e 35, which will be described later.

The address for a ~alue in the external memory 28 is formed from -the page address (Port 29 bits 0-3) and an address on the data bus. m e address section, which is transferred on the data bus, must be held in a latch 29 (~OS buffer memory)~

Inpu-ts:
To indicate that the battery is nearl~ exhausted, a power-down detector (bat-tery voltage threshold switch) TO is used~ Logica "O" at the input TO means that the computer must point out the restric-tion on the time remaining to the diver by means of a flashing display. Thus the computer 27 Al SO takes orer the function of an astable multivibrator.

If a clock function is to be provided, the inputs ~1 and 28 are to be used for setting the time of da~ and for switching ~he display mode.

The Port P1 and bits 5 and 7 of Port P2 of the computer 27 are led to a displAy circuit, which is shown schematically in Fig. 9~.
This con-tains the three light-emitting diodes and -the four liquid crystal displays~ each of the latter being preceded by a decoder and dri~er ~tage, 30 to 33~ The construction of these decoder and driver stages 30 to 33 is shown in Fig. 10 and will be described briefly below.

57 ~

For the decoder and driver stage 30-33 (LCD-decoder-driver), the InteTsil*module IC~I7211 Type AM has been selected. This module contains an oscillator, as well as all the decoder and 1river stages needed to drive a 4-digit display. A capacitor~
which determines the frequency9 is needed as an external componentu The type AM is microprocessor-compatible and has a code, which permits the suppression of a figure. m us it is possible to suppress leading zeros in the display.

It can be seen from Fig. 10, that:

- The data are to be transferred one figure at a time with the corresponding digit address. (The digit address is a 2-bit ~CD word).

- The relevant chip i9 selected through the chip-select line~
while a ~ata transfer can only take place on a positi~e edge on this lineO

For this circuit9 as shown in Fl~ 109 the code shown in Fig. 11 is used. With regard to this code; the ~ollowing points shon1d be notedo To clear a figure, it is only necessary to send the bi~ary value 1111 to the corresponding digit address~

With this code~ it is also possible to use the letter "E" as a special character for an error signal.

In Fig~ Column ~ shows the binary code and Column ~D the hexadecimal codeO

Since the Figures 10 a~d 11~ last discuæsed, only serYe to explain the ve~y schematic Figo 9B~ let us now make a comparison between the detail 39 Of Fig. 9A and two ~1ternati~e versions as shown in Figures 12 and 13.

*rrrade ~ark _ 58 ~ 3 In the discussion of the analog/digital converter 22~ it was mentioned above, that the latter only has a resolution of 8 bits.
~urther9 it was stated, that range switching must therefore be carried out. In this way, it is possible to mana~e with cheaper components, e.g, with the 8-bit ADC as compared with an ADC with a higher numbex of bitso Similarly, range switching can also be advantageous~ if the pressure sensor 6 is not directly capable of measuring both the water and the air pressure~ For both cases, a single changeover device can be used~ with which the reference voltage source 24 is switched as appropriate.

It has ~lready been pointed out above, that for this purpose the gain of the impedance converter 40 can be switched as shown in Fig~ 12, and where the reference voltage source 24' is simplifiedD
Here7 as ~lso in Fig. 9A (changeover stage ~4) and Fig~ 13~ the switches~ which are more conveniently in the form of FET switches, are represented as noxmal switches for the sake of clarityO

The reason for the preference for ~E~ swi~ches lies in the follo~ing: in order not to consume too much power~ the transverse current ~hrough the voltage divider should be kept as sm2ll as possible~ ~his means: the voltage divider should be designed with as high a resist~nce as possible. In order not to load the voltage divider with the input of the analog/digital converter, the voltage divider is connected to the analog/digital converter 22 through an impedance converter 40.

Another variant can be seen from Fig. 13; in which the voltage divider (24") iB switched over before the impedance converter (40).
me impedance converter 40 can be the same in each case. Although both variants (as sho~n in ~igures 12 and 13) are possible, they have the following disadvantages:

- ~11 commercially-available FET switches have to be operated with supply voltages of ~ 15 V and - 15 V;

- 59 ~ ~ 3 - With a "normal" FET, the cu~-off voltage is subj~ct to much too great a ~catter~ for such an FET to be driven with CMOS
levels;

- the only ~ailable ~`~OS-FET switch (4066) can also not be u~ed iD the circuit configurations abo~e, because of its On-resistance of typically 3 to 5 k, although it only needs a 5V supply.

Therefore~ as shown in Fig. 9~ a switchable reference Yoltage source 39 has been selected, because it is the solution, in which the On~resistanoe of the switch ha~ no effect on the accuraoy of the switching of the reference, while a ~IOS switch can be used. This circumstance takes account of the fact, that the FET switch of the switching stage 34 lies~ in each case, in the input branch of the impedance converter 40~ in which practically no current flOwsg as a result of which no voltage drop is to be expected through the On-resistance. As can be seen from ~ig. 9A, the switching stage 34 contains two switches S1~ S2~ which ~re opened and closed~altèrnatelyO Against thi67 an advantage c~uld be seen for the alternatives shown in ~igures 12 and 13~ in that only a single switch S is necess~ry for the changeoverl For the selection of the resistances, the following ratios have been found to be particul æly convenient:

4 ~3 R2 = 3 R3 Rl a 2 The zero point on the pressure sensor 6 can then be adjusted with the trimming potentiometer R4 and the sansitivity o~ the system can be adjusted through the trimming potentiometer R
Of the reference voltage source 24 of the an21og/digit~l converter 22~

~860~r~3 As already explained in connection with Fig~ 7 and the diode 10, the maximum ascent rate of 10 m/min must be monitored and an indication given if this is exceeded~ This monitoring can be carried out either in digital or analog form~ In both cases, he ~Idepth signal" must be differentiated.

In order to save space, a software solution would be desirable.
In order to obtain a reasonably realistic indication, a pressure change oYer 2 - 3 digital steps must be considered, since the last bit of any digital value can jump. Since a depth stage actually corresponds to 0.5 m, the diver must be monitored, with an ascent rate of 10 m/min~ over a distance of 1 - 1.5 m~
or over a time interval of 6 ~ 9 seconds~ which with cyclic measurement at 0.5 second intervals needs about 12 to 18 variables~
the difference of which would have to be formed continuously, in order to be able to differentiate the signal digitallyO The large number of variables, which will be needed for this differentiation, with only 45 ~ariables available altogether, gives preference to the analog differentiating stage. The differentiating stage 26~
which is now pxovided, generates, from the depth signal (position signal)~ a rate signal, which must be compared with a signal proportional to the limit value of the ascent rate~ The output of this comparator circuit then controls the TE~ indicator 10.

Programs and operation of the indicating device:

In order to be able to record the diving operations in their entire~y by means of the input values pressure and time, the complete program is divided into the four main progr~m sections which can be seen in Fig. 14. Each of these program sections also corresponds to a section of the diveO During a dive9 the di~er can run through these sections in -the most widely vaxying sequences; thi~ means that the program sections must also run one after another accordingly~

- 61 - ~ ~ 8 ~

Let us now explain these program sections in connection with the operation of the indicating equipment. With the closing of the main switch 9 (Figo 6), the whole of the electronics are connected to the supply voltage, the computer 27 (microprocessor) is switched on, whereupon it sets the program counter to zero and branches there to the address of the ~estart program (RSTAR~ .
The restart program initialises all variables, timers and counters to their initial values. At the end of the restart, the interrupt timer is initialised, enabled and started.

Every 0 5 seconds~ the main program is now started again by the auxiliary timer program ( T~E) and then runs as follows:

~he pressure is acquired in the program section PSNORC and then control is handed over to the Check-and-Set program (CHKSET).
The program section CHKSE~ keeps track of all timers and counters as appropriate and hands over control to one of the program sections Surface region (S~RFAC) Diving (DIVE) .
Ascent (DIVEUP~
Decompression (D
Displa~ (DISPLY) ~~

~he program section M SPLY ser~es the display and then goes into a wait loop, which must never run to completion9 since the auxillary timer must re~tart the main program before then. If~ ne~ertheless, the wait loop e~er comes to an end ~after approx. 1~5 seconds), the program goes into the software-error mode.

In order that all programs can work correctly~ a collection of sub-routines (LIB) is also needed. These sub-routines are called up individually by the various programs.

The individual program sections will be described with the aid of ~ig. 16.

First,however, let us interpose a few points on the memory configuration, with the aid of Fig~ 150 Since the computer 27 only has an 8-bit index register and the external memory can only be read by indexed addressing, it must be divided into pages of 256 bytes (corresponding to the index pointer range)O The storage of tables must therefore alæo take place page by page, in the same w~y for all five tables (for the individual altitude stages above sea level), so that the tables can be read with the æame programs~ Wi-th thi storage æystem9 "gaps" necessarily occur in the memory~ since the data do not always need a full page. This formation of gaps is aggravated by the differen-t table lengthsO (The table length decreases with increasing altitude above sea level).

If all this iæ taken into account, the 3k of table values need appro~imately 4k of memory, that iæ, one altitude stage needs 3 pages or 3/4 k~ So if 4k of R~l are used, there still remains one pa~e (256 bytes) for other data or programs.

It has already been mentioned, that the computer 27 (Fig. 9A~
has an internal 1k memory. In view of the large amount of data to be proceæsed and the extent of the program needed, this capacity is~ however9 by no means sufficient for program storage~

In order not to have to use any more additional modules~ the 4k of EPR0~ is so connected~ that it can be uæed as program and data memorieæ. Since the complete main program, including all sub-routines, needs over 2k of ætorage space, rather more tha~
2 k remains for the tableæ to be stored~ 3 tableæ can be accommodated in this æpaceO ~ecause the normal sporting diver does not~ as a rule, dive at altitudes of more than 2000 m above sea level7 only -the tables for the altitude stages 0 700 mt 701 - 1500 m and 1501 - ? m will be storedD

- 63 ~

The storage occupancy table then appears as shown in ~ig 17, where the first half of the program is held in the internal memo~y 17a of the computer 27 (~ig. 9A); the second half of the program in 17 b, the sub-routines in 17c and the tables in 17d to 17f of the memory 28. ~y means of pages 7 to 9 in the right-hand part of ~ig. 15, it is shown, for example, that Page 7 (17g) contains the first half of the decompression table, Page 8 (17h) the second half of the decompression table and the surface interval table, and finally Page 9 (17i) contains the zero-time table and the repetitive table. ~o be sure, the storage of the tables appears to be laborious, but is nevertheless cheaper, with regaxd to the components used~ than if one wished to compute the indicated values by only storing the mathematical ~elationships (insofar as this is possible).

In order to be able to read the tables, a plan must be prepared for the data structures and the table processing routinesO It has been shown by Fig. 15, that the individual tables æe accommodated in given pages in the memor~. ~his is imposed throu~h the restricted addressing capabilities and the requixementl that all tables are to be read out with the same sub-routinesO Now it only remains to fix the arrangement of the individual values in each table, 80 that each value can be accessed as rapidly--and - -simply as possible~ (The selection of the correct page and table is described later3.

~nly a li~ear representation is possible in the table memory~
i~e 7 all tables, whether they æ e linear (like the zero-time table), two-dimensional (like the repetitive-group table) or even three-dimensional (like the decompxession table)~ must be brought to and stored in a linear form~ In order to represent a multi-dimensional table in linear form, position markers (identifiers) are to be inserted in the table for end-of-line9 end-of-table et¢.

~ 7~ 3 ln order to obtain as small a table as possible9 an attempt must be made to accommodate more than one value or one value and one or more identifiers in one memory location.

~or working with the decompression table, the following routines will be needed:

With the maximum depth and the bottom time, the sum of the decompression times for a dive~ the repetitive group and the depth of the 1st decompression s-top are to be determinedO

- With the depth~ the bottom-time and the momentary`decompression depth9 the decompression time at this depth is to be determined9 - With the actual depth, the associated depth stage (according to the decompression table) is to be determined~

Thus~ with the input values depth and bottom-time9 a line in the table must be selected each time. The table must thus be provided with time- and depth-stage identifiers, in such a Way7 that the identifiers can be found simply and can be compared with the input v~1ues.- - --Thus the data arrangement shown in Fig. 15A was selected~ inwhich STID denotes a depth stage identifier, ZID a time-stage identifier, RG the repetitive group, ZEND an end-of-line markex~
SqEND an end-of-depth-stage marker and TA~END an end-of~table markerO
Now the following points are worthy of note on the existing tables:

- With one exception, all values are less than 64.
- All depth stages~ with one exception ~12m), are multiples of 5~ The greatest value is 70.

- 65 ~

-- Ihe botto~-time stages are also multipleæ of 59 greatest value 250.
- The repetitive groups go from A to L. If these are converted into numbers and a ~alue (M) is also inserted for the case where there is no repetitive group, the values go from 1 to 12 - The value 0 never occurs.

If the above knowledge is taken into account~ the following packing concept is obtained.

- The line~ in which the decompression time 70 minutes occurs (the only ~alue greater than 64)9 is omitted.
- The depth stage identifiers are stored after division by 5 (Exceptional rule for depth stage 12 m).
~he bottom-ti~e stage identifiers are also stored after division by 5.

If this is carried out consistently, then ~1l values are less than 64 and can be represented in 6 or 8 bits.
Ihat means: 2 bits axe fres for identifieræ and markers.

Selected identifiers: ZEND: Bit 6 set SlEND: Bit 7 set ~AB D : Value 0, since this identifier must be the same in all tables~

~he markers ZEND and STEND can thus be stored together with the repetitiYe group (which is always located at the end of the line)~

m e data arrangement of the decompression table now appears as show~ in Fig. 15B.

~he moæt importa~t part of the programs for reading the decompression tables:

- 66 ~ 6iOtj3 The selection of a line can be achieved relatively simply by "thumbing through" the table and comparing the identifier stored in the table with the input values.

Read-out pro~ (Selection of a line in "Pseudo-Pascal") SET POINTER To 1st TABLE VALUE ; 1st depth-stageid.
~E'~C~ VAL~E(POINTE~) DO W~ILE DEPT~STAGEID. < CON~ERTED INPUT ~EP
~EGIN: DO W~ILE NOT STEND
~EGIN: INCR~ENT POINTEa ~ETCH VALUE(POINTER~
END
INCREMENT POIN~ER
FETCH VALUE(POIN'~ER) ; Depthstageid.
END
INCRE~DENT POINTER
FE'rC~ VAL~E~POINTER) ; Timeidentifier DO WHILE TIMEIDENTIFIER ~ CONVERrrFD INPUT TIME
~EGIN~ DO W~ILE NOT ZEND
~EGIN: INCREME~T POINTER
FETC~ VALUE(POINTER) END
INCREMENT POINTER
END
; The pointer now points to the 1st value of the desired ; line On the basis of this program section, the desired values can easil~ be determined:

- The depth of the 1st decompression stop is the 1st value in the selected line.
- The sum of all decompression times for a dive is the ~um of all values between the start of the selected line and the ~END identi~ier.

~ 3 - The repetitive group is in the same memory location as the ZEND identifier.
- From the actual decompression depth, the position of a decompression time within the line, and thus its value~
can be determined~

For reading values out of the decompressisn table, the following 3 sub-routines were written:

~DECOW: Determines the following values:
Sum of the decompression times of a dive.
Depth of the 1st decompression stop.
Decompression time of the 1st decompression stop~

~DEKOT: Determines the decompxession time for a given decompression depth stageO

BRPDEC: Determines the repetitive group in the decompression table.

~he selection of a line essentially takes place in the sub-routine XDECTB, which is used in the above sub-routines.

qhe conversion of an actual depth into the associated depth stage is carried out~ since substantially only multip~es of 5 occur here~ with ~ rounding formula in the sub-routine ~DES~
without using the decompression table~

Repetitive tables:

For working with the repetitive table~ the following routines are neededO

With the depth and the repetitive ~roup, the added time is to be determined.

- 68 ~ 3 With the depth and the time, the repetitive group is to be de-terminedO
- With the actual depth stage~ the next deeper depth stage (in relation to the repetitive table) is to be determined.

~hereforep with the one input value - the depth - the position of the value in the line can be determined. The second input value is either the repetitive group, which ~hen correctly selected states the number of the line, in which the added time is to be found~ or the time, with which, by comparison with the value in the table, the line, the position of which corresponds to the repetitive group, can be found.

Taking accoun-t of this knowledge~ a data arrangement was selected~ containing no identifiers, but only end-of-line marks. ~he position of a value in the repetitive gro~p is known, if the line and column, in which the value is located, are known. The column corresponds to the position of the value withLn a line. In ordex to be able to determine this poæition of the value within a line, the headline of the repetitive table (the line with the depth stages) is stored as a pointer line, separated by a TABEND mark, before the actual data. ~he position of the desired value in the line can now be determined by comparing the input value ~Depth"
with the values in the pointer line. Identification of the line is not necessary~ sinoe the repetitive groups have been so selected, that they agree with the position o~ the lines in the table.
The selected data arrangement of the repetitive tables is to be seen~ with regard to the pointer line~ in Fig. 15G and, with regard to the table values, in Fig. 15D. The data of the repetitive table are stored linearly, beginning with the headlineO
The program section for reading the repetitive table~ namely the dete~mination of the position of a value within a line, can be produced by comparing the input depth with the pointer line~

In "Pseudo-Pascal", the following is obtained for the determination of the position within the line:

SET POS = 1 SET POINTER TO ~EGIN OF POINTERTAB.
~ETCH VALUE (POIN"l'~K~
DO WHIIE VALUE (POINTER) ~INP~T DEP1 BEGIN: INC~ENT POINTER
INCBEiMEN'r POS
~ETCH VAL~E (POINTER) END
l~e variable POS now contains the position of the value within the line.

~he variable POS is not actually "counted up", but is determined from the difference in the pointer value at the start and end of this progra~ section.

On the basis of the above program section~ the desired v~lue can easily be determined:

- The added time can be determined, by moving the pointer forwaxd by the number of lines~

"Pseudo~Pascal" program for this:

DO WHILE REP. GROUP ~ O
~EGIN: DO W~ILE NOT ZEND
~EGIN: INCRE~DENT POI~rER
~ETCH VAL~E (POINT~R) ~D
DEC ~ T REP. GROUP
END
POINTER = POINTER ~ (POS. IN THE LINE) _ 70 ~ 3 ~he ~f~ J~ can be determined, by reading the value in the correct POS in each line, and comparing with the input time.

"Pseudo Pascal" program for this:

S:ET POINT~R TO BEGIN OF DATA
AUXPOINTER = POIN~'iR ~ (POS . IN T~E LINE ) ~(~ VALUE (AUXPOIN'I~
DO W~l:LE VALI~E (A~XPOINTEiR) ~ TIME
13EGIN: DO W~LE VALUE (POINTER) ~ ZEND
:13EGIN: INCREMENT POINTER
~ ETCH VALllE (POIN~ER) ~D
AUXPOIN'l'k~EI = POINTER + (POS . IN ~E L~E) ~ND

~he next deepex_~pth ~ta~e can be determined in the pointer line without usi~g the further table values. ~he position in the line is simply determined and the next value is read, but in the pointer line itself~

~or reading-out values from the repetitive table9 the followi~g sub-routines have been written:

~ZZ~: Determination of added time BRPG~W: Deter.mination of the repetitive group (under water) ~DESi~N: Dete~mination of the next deeper depth stiage~

~he determiniation of the position within the line essentially ti~kes place in the sub-routine X~EP~B, which is used ~y the 3 sub-routines aboveO

m e zero-time ta~le is stored and read in the same way as the repetitive table. Thus a pointer line and (in contrast to the repetitive table) only one data line is stored.

Thus9 for reading (as with the repetitive table~9 first the position in -the line is determined and with it the required zero-time.

If, on the other hand, the surface-interval table is considered, it can be seen, that the difference from column to column is approximately the same in each line. ~his is also underst~ndablet because a diver always goes from one repetitive group to the next lower after a given time, and these times should be the sa~e, irrespective of the initial group.

~or this reason, instead of the complete table, only the lowest diagonal is stored. Since this table only works with the repe-titive groups and only one (diagonal) line is stored, this can be stoxed in such a way, that the repetitive group corresponds exactly to the position in the line.

Under these circumstances, working with this table is simplicity itselfO

The surface interval time (according to the repetitive group) is looked for in the table and is compared with the value stored there. ~s soon as the two values are equal, the surface interval time is set to O and the repetitive group is decreased by 1.

So far3 only the way in which a given value is sought for within a table has been describea. Now it will be explained how the page in which the table is located in the external memory is found9 and how the pointer is set to the start of the table wi-thin this page~

- 72 ~ 3 To select the table, an offset must be determined~ depending on the altitude stage and corresponding to the page of the first table for this range. To this offsety a further offsetl which corresponds to the position of the table within the set of tables9 must be added. m e sum of these two offsets is to be applied~ as the page address~ to the lowest 4 bits of port 2.
When the page has been determined in this Way7 the table still has to be selected7 since in many cases 2 tables are accommodated in one page. Iherefore~ if the table is not at the start of the page, the values in the page must be "thumbed through" until the first TABEND mark, in order to set the pointer to the beginning of the 2nd table.

For finding the start of the table, the sub-routine FNEXTr has been written. This searches a memory area for the TABEND mark and sets the pointer to the value after this mark.

From the previous explanations of the display device, it was shown that it has to react to two kindæ of error~ namely:
ut of ~ange: If the diver enters a range (in position or time) which is no longer co~ered by the tables.
oftware-Error: If, during a calculation, the computer ru~s into an overflow or underflow or if the timer fails~
n order to detect these errors~ in all table processing routines~

- the limits of the tabIbs are monitored and, if these limits are exceededg the Out-of-Range flag is set~

during every multiplication, the result is monitored a~d~ if i-t can no longer be represented in 8 bits, the Software~error flag is set;

- 73 ~

- similarly~ the result would be monitored during a division, or a check would be made as to whether a division by zero had been carried out. However, this monitoring becomes superfluous in our case, since a division by zero can never occur~ In fact9 the divisor is always loaded with a constant, which is always greater than ~ero, one instruction before the division routine is called up.

Now the storage and handling of the tables has been expl~ined, the program sequence and the program structure are to be described.
The tables 11 to 18 and 20 to 22, mentioned in the description~
are to be found at the end~

Each main program is described by the program documentation and the associated flow diagram. ~he program documentation is so constructedS that it describes the flow diagram verbally and congruently. Thus, by means of the flow diagram and the program documentation9 any desired point can be found rapidly and easily in the assembler code.

As shown in the program structure represented in Fig. 16~ the program begins, after the main switch 9 is turned on (see ~ig. 6)~
with the ~estart program RSTART7 This is executed as shown in ~able 110 Eve~y 0.02 ~econds, the auxiliary timer program H~ ~ is executed as show~ in Table 12, and in the process it generates the 0.5 s timing pulse~ with which it starts the main program cyclically every 0~5 secs, beginning with the program section "Detect pressure~
- PSNORC.
In order to be able to detect the ent~y into the water by means of a pressure change~ the latter must be OtO2 bars in a second.
~he pressure change of 0.02 bars corresponds to an air column of 200 m~ ~o be sure, no human being can travel through a vertical distance of 200 m in one second in air without jet propulsion, but the diver achieves a rate of change of pressure of 0.02 bar/s ~ 74 when he changes from the air into the water. A head of water of only 20 cm is sufficient, to produce the pressure of 0~02 bars, and every diver will submerge to a depth of 20 cm within a second of entering the water.

qhis 20 cm head of water is arrived at on the one hand from the resolution of the pressure sensor 6 and, on the other hand, from the fact that the change in pressure must amount to at least 2 digital quanta. If the indicating equipment is~ erroneously, first switched on under water (an abnormal case)~ this is detected b~v a test, which ascertains whether the first pressure measured is greater than 1~2 bars. m is is significant because9 in such a case, the air pressure could not have been determined in advance.

The reason for the selection of the limit of 1.2 bars is that the air pressure at sea le~el can reach9 at most~ 1v06 bars.
If the case where the diver dives into a lake below sea level is excluded7 the test can be made at 1.2 bars without question.
So if the main switch 9 is actually first operated under water, the indicating equipment then works under the assumptio~ that the atmospheric pressure at the diving location is = 1 bar. ~rom that time on the depth gauge of the equipment according to the invention is now only-as good as---most-conventional depth gauges~
which do not distinguish between di~ing in mountain lakes and the sea.
1 bar then corresponds to the atmospheric pressure at sea level and is thus~ for our system, the zero point from which either the depth of water or the altitude above sea level is determinedr The program sequence of the program sectio~ PSNORC can be seen in det~il from Fig. 17 and also from ~able 1~.
In the Figure, 43 denotes a test9 whether the indicating equipment has been switched on under watex; 44 a test9 whether the diver has entered the water; and 45 a conversion of the pressure~ so that it is matched to the gain = 1.

0.~3 ~ 75 -At this point it should be mentioned that in each case (in the computer 27 and in the analog/dig;tal~coverter) lO bars correspond to 200 bits, so that one bit gives a resolution of 005 m. Thu8 the depth gauge i~ also accurate to 0.5 m9 while the preparation of the data for use in the tables becomes very simple, since the depth, determined digitally, corresponds exactly, when divided by two, to the actual depth in metres~ ~owever, the ratio of 10 : 200 means that the numerical value of -the pressure~
processed furt~er in the computer, is too great by a factor of 20 when compared with the actual pressureO Further, it should be mentioned tha-t the calculation of the diving depth by means of the pressures PNEU and PN~LL is xeduced to:
DEPTH = (PNE~ - PNULL) ~his means that the diving depth carried in the computer is greater than the actual diving depth by a factor of 20 ~urther~ it can be seen from ~ig. 16~ that the program section PSNORC is followed by the program CHKSET, the details of which can be seen in ~able 140 At this point~ the library program shown in Fig. 16 should also be discussed.
All the sub-routines used are accommodated in this program section.
m ey are - All the table processing routines described above.
- A few mathematical programs.
~or this purpose, the library program has:
- A subtraction with direct access to the minuend.
- A subtraction with indirect access to the minuend.
(~oth subtractions transfer the sign information in the carry bit and can thus also be used for comparison of two numbers), - Multiplication with direct access to the multipliex, (This multiplication of 8 x 8 bits delivers a 16-bit result~
The 16-bit result, consisting of lower 8-bits and upper 8-bits, is only used in the main program DISPLY, otherwise computatio~
is only carried out with the lower 8 bits.) - 76 ~

- A division with direc-t access to the divisor. (The original 16-bit by 8-bit division has been amended into an 8-bit by

8-bit division, since the computer works with 8-bit values.
In order to test for an error, the carry bit, which is set in the event of an overflow, can be used~) - A sub-routine, which converts 8~bit and 16-bit binary numbers into ~CD numbers, in order to be able to transmit the values to be indicated~ to the display in ~CD code. In addition~
this sub-routine detects leading zeros and sets ~ ex instead of the leading ~CD zero, so that the code called for in ~ig. 11 for the blank can be provided. Basically, it would be advantageous~
if the library is not stored as a coherent program block, but instead the individual sub-routines are inserted in the main progr~m~ so that as many pages as possible æ e fully utilised~
i.e. that few l'gaps'l occur in the program memory and few page jumps are needed~ However, for the program structure described, this is not advisable, because the complete program takes up approximately 2~ k of memory, i.e. it is necessary to work with memory bank switching~ ~or the sake of simplicity, we place all sub-rcutines after the 2-k boundary~ so that the memory bank only has to be switched before and after each ~sub-routine" call and the main pro~ram never runs beyond the ~-k limits which is to be avoided wherever possible, since it would c~nsiderably complicate the memory-b~nk switching.
While still in the program section C~KSET, the decision is taken, depending on the values and differences determined in this program, on which of the programs following C~KSET in Fig. 16 is to be executed~
The sequence of the program section S~FAC is shown in Fig. 18 and in Ta~le 150 Details of the program section DIVE can be seen in ~`able 16.

~ 77 ~ 3 In the former, 46 denotes a test~ whether the di~er is snorkelling;
47 is a test~ whether the diver leaves the water; 48 is a test~
whether the diver has changed to the diving status; 49 is a test, whether the diver is in a surface inte~val and 50 is a test~
whether the repetitive group has become zero.
Ascent program DIVE~P: In order to be able to check the ascent with a minimum speed of 8m/min, the diver must be "observed"
over a longer period of time. This "observation" consists of checking, whether the diver is in the "ascent cone1l. The ascent cone means the range, through which the diver moves in the period of 30 seconds, ascending at least 4 m in the vertical direction and not diving below the depth stage, in which the ascent was begun. A new ascent cone is set eve~y 30 seconds, provided the diver has not left the ascent cone before then and is continuing to ascend. m e sequence of this program is shown in Table 17 The decompression program DECO is described in detail in Table 18.

As can be seen particularly from ~ig. 7, all these programs lead to some kind of indication, which is assigned to the display program DISPLY~
In order to be able to drive the four--display units 13 to-16- - -~see Fig. 7, 9~) with four-digit numerical displays, a total of 16 digits must be addressed. These 16 digits are addressed through a 4-bit code-word, which has the structure shown in Table 19. Thus the code-word for the selection of digit No, 3 in displaY 15 i~ ex -Table 19: Display ~oO Digi~ No.
.
3 0 1 2 3 ~
14 4 5 6 7 ~ ~e~ code - 7f3 - ~B6~ 33, Through this code-word structure, it is very simple to send the individual output values to the display. In fact, a display counter (DISPCO) can be incremented from zero to 15 ~nd the rele~ant digit can be sent in BCD code to the display each timeO Table 20 illustrates the flow diagram of this program section, Now the individual program sections have been described, let us refer to ~able 21, in which all program sections are shown in a memory occupancy table for program storage. In addition to this, Table 22 contains a list of all variables and sub-routines used~

Further, the status and flag conventions are shown in the following tables 23 and 24 Table 23:
Status Significance status/statusreg.
, SURFAC At surface STATRG Bit O = 1 DIVE Diving " " 1 = 1 DIVEUP Ascending -" " 2 = 1 DECO Decompressing Port 2 Bit 5 = 1 SNORC~ Snorkelling Port 2 Bit 6 - 1 o~TRNC out Or Range Port 2 Bit 7 = 1 ~able 24:
Flag ¦Significance Status/Statusreg.
SFINT Surface intervalSTATRG Bi$ 3 = 1 KORBT Bottom-time correction " Bit 4 = 1 DEKEND End of decompression " Bit 5 = 1 SERROR Software error'~ Bit 6 = 1 1. Bit 7 = x ZEROT Zero-timeFlag Fl: = 1 - 79 ~

It should be noted, that it has been shown in the above statements, that the tables of the Pressure~Chamber ~aboratory of the ~niversity of Zurich are mainly stored in the table memories9 because these tables are particularly suited for the compilation of the whole dive from individual diving sections, they have the capability for evaluation of preceding dives during a repetitive dive and do not only relate to dives at sea level, but also in mountain lakes up to an altitude of 3200 m. Above all, with them~ digital processing can be carried out easily. ~owever9 it is understood that the invention is by no means restrictad to the use of these tables, but that other tables, for example those of the ~S Navy, can also be used.

Even though no special display for the actual time-of-day has been shown and described with the aid of ~ig. 7, it was mentioned in the description~ that it is advantageous to use the timer9 which exists in any case, to state the time of day. ~his requires that the power supply to the circuit parts assigned to this time display should be maintained, even after the main switch ~ is turned off.

Decompression table for O - 7OO m above sea level Table ~Depth Di~e Decompression stopfiRtPve ¦ Depth lDive DecompreFSiOn stops P~tPivet-~
rn mln j 7 9 6 3¦GroUP m min i8 1512 9 6 3 Group _ J 10 F
1!~i 120 11~ K 15 2 6 G
150 15 L 20 3 11 H .
_ 50 H -25 5 20 J 7 J 4 ~ 30 3 10 30 K

1J0 8 H , 10 5 F
:2 5 50 12 J 15 3 8 H

3 30 K ~i O Z5 3 10 27 10 38 L 30 5 10 35 K .
. 40 2 5 12 15 50 K

9 H 60 3 12 20 30 70 ~0 325 52 L 30 1 3 913 38 K
_ 20 G 40 1 5 3 1718 58 K
9 H 10 2 3 5 .

602 10 25 50 L . 30 2 3 1015 20 50 L
_ le 2 I Zero-ti~e limits rn 9 ¦ 12 ¦ 15 ¦18 ¦ 2Q ¦ 25 ¦ 30 ¦ 35 ¦40 min 1 200 ¦75 ~ ~ 25 ¦ 20 ¦ 15 ¦10 I , , , . ~ .
_ - _ - 81 ~ 5~

Repetitive system for O - 700 m abo~e sea level Surface interval table (min) ~able 3 ~ _ Repetitive group at the end of the surface interYal L K J H G F E D C B A "O"
L 14 30 47 6B 91 127 149 174 236 2s5 ~40 ~? ~ 16 34 s5 83 113 135 160 lq4 240 426 . J 18 39 65 98 119 145 180 225 409 o~ H 22 47 80 131 127 163 ~-36 394 26 s9 80 106 139 186 372 \ ~h 34 55 80 113 160 346 \ ~7~ E z 47 80 127 312 ~n ~iS D 26 59 106 292 ~ B 47 233 Table 4 ~ I Added~tIme or repetitive table _ Depth 6 9 1215 20 25 30 35 40 45 50 s5 60 65 70 L 300 160 ~5 69 55 45 39 34 30 27 25 23 21 K ~400 250 127 80 59 47 39 34 29 26 24 22 20 18 J ~00 150 lol 67 50 40 33 29 25 23 21 19 17 16 . ~P ~ ~-30 il3 8~ 5s 42 34 27 2s 22 19 17 16 15 14 G>200 135 8s 63 44 34 27 22 20 18 16 14 13 12 11 F200 108 61 47 34 26 z 17 16 lq 13 12 11 lo 9 ~ ~85 q8 34 27 20 16 13 lo 13 9 8 7 7 6 6 P~ C61 37 26 22 16 13 lo 8 8 7 6 6 5 5 5 _ 2617 12 lo 8 6 6 4 4 3 3 3 3 3 3 8~

Decornpression t~ble for 701 - 1500 m above sea level Table 5 P time Decom~ression stops,Ritpive Depth Dive Decompression stops Repet m ¦min 16 13 10 7 4 2Group mrnln ! 16 13 10 7 q 2 Group 12 ¦120 5 H 10 j 2 3 D
F l S ¦ 3 5 8 F
. 75 8 H 20 2 S 5 11 G
'iO 13 H 35 25 3 7 7 13 ~I

? )I ~ 2 ; / ~ 2 2 'iO 12 25 J 30 3 6 8 10 20 J

120 20 37 4~ 6 8 9 17 32 J

35 3 45 139 G 4 522o5 1 4 6 6 10 19 HH
2 5 40 5 5 17 H . 30 2 5 7 10 16 28 J

10 15 30 J . 10 3 4 5 10 F

l 3 D 25 3 4 8 10 10 25 J

5 9 f . . _ _ _ 60 6 15 15 31 J _ 20 5 6 6 8 10 30 H

Table 6 Zero-time limit~
, , _ l _ m ~9 _ 12 1 15 18 20 25 1 30 35 __ min 720 90 1 30 _ 20 15 10 1 5 4 _~

- 8~ 8~

Repetitive system for 701 - 1500 m above sea level Table 7 Surface interval table (mi~) .._ Repetitive group at the end of the sur~ace interval J H G F E D (' B A "O"
. . .
J 17 35 sq 87105 125 150 183 265 ~ep H 19 42 7189 109 134 166 250 e G 23 52oq 90 llS 147 230 ~4~ F 2946 67 92 124 207 ~e E 18 39 64 96 178 \ ~ ~ C z5 58 141 ~Ce E~ 33 115 `~\ o~,_ 8l ~able 8 Added-time or repetitive table Dept~ 6 ~ 10 12 15 20 25 30 35 40 45 50 55 60 _ _ >225 190 125 93 60 44 35 30 25 22 20 18 16 G >330225 130 - 92 71 47 35 29 24 21 18 16 15 13 ~ f 330132 90 67 53 36 27 23 19 16 14 12 11 10 D 103 6~ 47 37 30 21 16 13 11 10 9 7 7 6 _ 32 21 16 13 11 ~ 6 5 5 4 4 3 2 2 ~ ^ -- 84 ,~

o ~ o _ _o _ _ _ ,. o _ ~ _ ~

~) U~

ca n3 r~ ~ o o ~ ~ ~ U~ o U~ o U~
O O ~r~ ~ r~ r~ C`l C`J ~ .~) ~ r~ r~ r-) ~ ,r~ r~ ~ ,r~
I:n p ~
h ~ ~ O ~ o ~ o o u~ o Irl o o Ul o U~ ~ ~ o o ~ U~ o o o O rl o h R
~ ~1 ~
~3 .
~--i r1 r~ ~L) Z _ J 3 _ Z ~ J ~ Z Z Z 3 _ -- _~ 3 O ~ a0~
h~ o ~ ~ o o u~ o ~ ~ ~ ~n o U~ o t ~ ~;-~ ~ _ ~ ~~ ~ r~ o _ ~o O ~ `D '-~ O

o ~
.~ il 11 11 11 11 11 11 ~;
~-, + + + + + ,~ + 1~
o rd~ r_ _ O .,~ ~ O Oq ~ q ~ O
,J ,1 ,~

O ~ 0 ~ O C~l r.~ ~ O~ O ~ O ~ ~ t) i~ rd .~

r1 .
r~

~> ~rd _ ~5 --~d ~ ~ ~~ = = = = o O u~
h 13 ~ o _ ., o ~
t~ $ r Ul ~d o 0~-- o Q o o O ~ ~ O
~ ~ l l l l l l l l h ~ ~d I
~ ~ o ~ V~ U~ o o o O h-r a) o R
..
+

a~ ~7 q~
3 ~ Z Z Z Z; Z Z Z Z Z Z -~ :3 -' 3 -' o.c a~
h~ o o o o o o o o ~ C~ o o CO ~ ~ ~ U~

.~ + o ~ o ~ o ~ o ~ ~ co o u~ ~ l~ o ~ l~ ~ o o r~ o ~-~1 ~t~ ~ ~ ~ C~C`~ C`~ ~ --~ C`l ~ ~ ~ _I ~ ~ _ C~` ) O CO CO O`
+ ~
~11 `D
+ + + ~o o a) ~ U- o ~ o U~ o o ~c~co o U7 ~ 1~ o~ co O r_ o C`J
E~ _ ~ co ~ co .rlll ll ll ll ll ll ll l~ ll ll ll ll ll ll ll ll ll ll ll - ll ll ll +~ ~ ~ Ln Ul ~ ~o ~ ~ O OO ~ ~ ~ ~ ~ r~r C`l ~ ~ I_ ~
- +++~ +++++ +-~++l++ +l+~++ +

C) ~1 ~ o u~ Od- s~ o ~ ~~ ~ o ~ ~ t~ ~ o l~ _ o l co --~ r~ G` CO CO ~t co U~ co ~ co co + + +
r rl o ~ ~ S ~ Ad ~~ p ~ D ~ ~~ D
_ o ~ , o ~i _ . _ Table 11 1 ;*~ ***-~*~*********~*~xxxx**~**~ x~ **
Pro~ram: 3 '~ RSTART
RSTARl' 4 ;*
Page 1 5 '* ~~ ~ ~~~
7 ;* T~IS PROGRAM rNITIALISES ALL INITIAL VAL~ES
8 ;* IN THE VARIABLES, T~IER AND COUN'l'~HS, 9 ;* ALSO 'l'i1~ INTERRUPT COUN'l'E~ IS INIl'IALISED, 10 ;* ENA~LED AND STARTED.

11 ;* AFTER E~ECUTION OF THE ABOVE, A JI~IP IS MADE

12 ;* TO THE START OF T~E MAIN PROGRAM.

13 ;*

14 ;* NOTEo THE CO~iPLETE DATA-~D~lORY (IN'~ERNAL) IS

15 ;* FIRST SET TO ZERO AND TEEN TEE RELEVANT

16 ;* ~ ORIES, ~ICH MUST ~E NON-ZERO, ARE

17 ;* SET.

18 ;* LIKhWISE, ALL STATES AND FLAGS ARE SET

19 ;* TO THE START VALUE.

20 ~*

21 ;* -~ AT SERFACE -~ STATRG: = 0000 0001

22 9* -~ PORT2: = 0000 0000 , THAT ~EANS

23 ;* NOT SNOR~rEL

24 ;* NOT OUT OF RANGE

25 ;* NOT DECOMPRESSION

26 ;* -~ AT ZEROTIM~-DIVE -~ FLAG F1: = 1

27 ;* -~ DEPTH STAGE:= 6M ~ DEST: =12

28 ;* -~ DOWNCOUN'~ER FO~ 1SEC -~ DOWNC1: = 2

29 ;* _~ DOWNCO~NTER FOR 30SEC -~ DOWC30- =61

30 ;* -~ AL~I'n~DE ABOVE SEA LEVEL -~ AASL: = 7

31 9~ XXXXXX FOR (0--700)M ~ ~CDC~C`L)~

32 ;* ~ INTERRUPI~COUNTER T: =125;

33 ;*

34 ;*

35 ;* T~IS PROGR~I ONLY RUNS ONCE, WHEN TEE;

36 ;* EQ~IPMENT IS SWITCHED ON. TH~S THE ~IN

37 ;* SWITCH ALSO FUIFILS THE F~NCTION OF THE

38 ;* RESE~ SWITCEo

39 ;*
4o i*
42 ;*
43 ;*
44 ;*
4~ ;*
46 ;~xxxxxxxxxxxxx-xxxxxxxxxxxxx~xxxxxx-xxxx~txxx-x-~*~x-x~*~x~x 47 ;
48 ;
49 ; EQEATES
50 i***~HHHH~xxxxxxxxxxx~x 51 ;
52 ;
53 ; ~ARI~BLES

Table 11 55 ; DEST EQU 55 Program: 576 ' AASL EQU 51 RST~RT 58 ~ DOWNC1 EQU 27 Pag~ 2 609 ' DOWC30 EQU 26 61 ; SUBROUTINES
62 ;
63 ; SUBD EQU 308 64 ; HTIMER EQU R7 65 ;
66 ;
67 ;
68 9 STATE~DENTS
69 ;~*~**HH1~H*~*****
7o 3 71 ;
72 ;
73 RSTART:
74 ;
75 ;
76 ;
77 ,* SET ALL TIMERS, COUNTERS, VARIABLES ON ZERO
79 ;
80 ;* SET S~NDRY ~IORIES NOT EQUAL TO ZERO *
81;
82 ;
83 ;* SET STATES AND ~LAGS
84 ;
85 ;
86 ;* SET INTERRUPT-COUNTER
87 ;
88 ;
89 ~* SET HTIMER *
90;
91 ~
92 ;* EN~BLE AND START INTE~R~PT-COUNTER *
93 ;
94 ;
95 ; * GOTO MAIN PROGRAM *
96 ;
97 ;
98 ;
99 E~D

Table 1 ? 1 ;-~****3~ ~x-*;~x-~x-****-x-~;*~x~x x X-#-~-X~ X-*~ X~*
P am. 2 ;*
rogr . 3 ;* H'rIllE
HT~IE 4 9 *

7 ;* SUBROUTINE FOR GE1~3RATING A 0.5 SEC
8 ; * TI~IING PUI SE
9 ;*
10 ;* THIS SUBROUTINE IS CAL~ED EYERY 0.02 SECS. ~Y '~E
11 ;* INTE~RUP'~-COUNTER. THE AUXILIARY T~`~R (HILEST~ ER) 12 ;* IS DECREr~TED. WHEN IT REACHES 'rHE VALUE ZERO~
13 ;* 0.5 SECONDS HAVE ELAPSED. ~~
14 ;*
15 ;* GOTO ~~ START OE MAIN PROGRAM
16 ;*
17 ;* i.e. 'l'~E STAC~POIN~ER IS SET To 1 AN~
18 ;* '~HE ADDRESS OF T~IE MAIN PROGRAM IS
19 ;* WRITTEN IN THE STAC~ SO THA'r THE
20 ;* HILESTI~DERRO~qINE CAN ~E LEFT WITH
21 ;* RETRo 22 ;*
23 ;* OTHERWISE~ RETURN WILL LEAD TO A ~RANCH TO THE
24 ;* POINT IN THE MAIN PROGRAM~ ~nD~RE IT WAS INTERR~PTED
25 ;* PY T~E INTERRUPT CO~NTER
26 ;*
27 ;* NO'rE: THIS PROGRAM ~EGINS AT ADDRESS 7H
28 9* - 7H = TIMER~ RRUPT VECTOR
29 ;*
30 ;*
31 ;x 32 ;*
33 ;*
34 ;*
35 ;*
36 *~X~*XXXXX3~XXX3tK*XXXX*XXX-XXXXXXXX~X7~X~**
37;
38;
3 9 ; EQUATES

40 ; ***-x~x ***~x~*

41 9

42;

43 HT~ER EQU R7

44;

45;

46; STA ~ENTS

47 ;~3~x~r~** x~****

49 ;
50 ;* ~00~ ~OR SWITCHING ON EQ~IP~ENT *
51 ;* AT T~E RETU~N ADDRESS IS T~E JUMP *
52 ;* ON RESTART - 7 RESET-VECTOR
53 ;
54 ;

9 _ Table 12 55 ;* SET HTIMER AND TIMER *
56 .
Program: 57 9 HT~ 58 ;* GOTO START 0~ ~INPROGRAM *
59 ;~ SET FLAG FOR INCIRCUIT EMULATOR
Page 2 60 ;
61 ;
62 ;* SET STACKPOI~TER = 1 *
63 ;
64 ;
65 ; * LOAD RETURN V~LUES IN
66 ;* REGISTERS 8 AND 9 67 ;
68 ;

- 9o~

Table 13~ x~x x ~ x x~x~ x x x x x-x x x x x-x-x~*~ x-x-x~x~
2 *
OE 3 ~* READ PRESSU~E/S~ITCH TO SNORKELLING
PSNORC 4 ;*
Page 1 5 , x~
7 ;* THIS MAINPROGRAM READS IN TME PRESSURE (PNE~) 8 ;* THROUGE PORT PO AND PROCESSES IT
9 ~*
10 ;* A) TO DE~ECT WHEI~ER THE DIVER
11 i* ~AS SWITCHED THE EQ~lPi~ENT ON
12 ;* ~NDE~ WATER~ ~~
13 9 * S TATTJS: = OUT O~ RANGE
14 ;*
15 ;* B) TO DETECT WHE'l'~ER TEE DIVER
16 ;* HAS ENr~ERED T~E WATER AND
17 ;* FOR DIRECT CHANGEOVER OE r~E
18 ;* GAIN 0~ TEE ADC~ ~~
-19 ;* FLAG: = SNORKEL
20 ;*
21 ,o* C) TO EO~ DELTAP~ WEICH ON r~HE ONE
22 ;* HAND CONTAINS THE DIRECTION 0~
23 ;* DIVING AS THE SIGN WHILE l'~E DIVER
24 ;* IS IN THE WATER AND~ ON THE OTH~R
25 ;* EAND~ CONTAINS THE INFORI;ATION~
26 ;* WHE~K TEE DIVER IS IN THE WATER
27 ;~ OR NOT~
28 ;* ~DELTAP IS COI~PUTED AT ONE-SECOND
29 ;* INTERV~LS~
3o ;*
31 ;* D) FOR mE AIR PRESS~RE AT ~E DIVING
32 ;* LOCATION ~~ PN~IL: = AIR PRESSURE
33 ;*
34 ;* NECESSAR~ INITIALISATION BY:
35 j* RESTART~
36 ;*
37 ;* DO~NCOUNTER o~ DO~NC1: =2 38 ;* OLD PRESS~RE ~ PALT: =O
39 ;* NOT SNORKEL ~~ PORT P2 BIT6: =O
4o ;*
41 ;* ~OTE. CYCLIC STARqING OF THIS PROGR~M
42 ;* EVERY 0~5 SE'C.
~3 ;*
44 ;*
45 ;
46 ;*
47 ;*

48 9*

49 ,*

50 ;*x-x~x-~xxxxx~ -x~*xxxxxx~x-xxxxxx-*x*~xxxx~xx-xxxxx-~x~x~*

51 ;

52 ;

53 ; EQUA~ES

54 ;***~HHH~X~HH~X~HH~*~

- 91 - ~ ~ 86 ~ ~ 3 Table 13 55 ;

Pro~ram: 57 ' VARIABLES

P 2 59 ; PALT EQU 63 age 60 ; PN~ EQU 62 61 ; PNULL EQU 61 62 ; DE~TAP EQ~ 59 63 ; STA~RG EQU 24 64 ; DOWNC1. EQU 27 66 ; S~BROUTINES
67 ; SUB EQU XXXXXXXXXXXXXX
68 ; SUBD EQU XXXXXXXXXXXXXX
69 ;
7o ;
71 ;
72 ; STATEMENTS
73 ;xxxx~xxx-x-x~xxxxxx~x-xxxxx 74 ;
75 i 76 ;
77 ;
78 PSNORC:
79 ;
80 ;* INPUT OE PNE~ *
81 ;
82 ;* ADC ON, EPROM O~F -~ PORT2 BIT4=1 *

84 ;
85 ;* START ADC *
86 ;
87 ;
88 ;* WAIT ON CONVERSION CO~PLETE! *
89 ;
90;
91 ;* READ ADC *
92 ;
93 ;
94 ;* TES~ PALT=O ?~ NO -~ GOTO PS1 95 ;
96 ;
97 ;* YES-~ TEST PNEU ~102~AR ?7 NO-~ GOTO PS2 98 ;
g9;
100 ;* YES-~ THE EQUIPME~T HAS BEEN SWITCHED ON bNDER ~ATER
101 ;* SET STATUS = OUT 0~ RANGE, BY LIGHTING LED
102 ;* THROUGH PORT2, LINE 7 (BIT7 = 1) 10~ ;* CHANGE GAIN OE THE ADC THRO~GH PORT2 LINE 6 104 ;~ (BIT6:=1) 105 ;* AT SNORKEL - PORT P2 BIT6:=1 106 ;
107 ;
108 ;* SET ~OR REDUCED DEPT~-~ETER WORKING
109 ;* PNULL = 1BAR *

- 92 ~ 5 Table 13 110 , Prog~am 112 ,* GOTO CHKSET *
PSNORC 113 ;

117 ,* PALT: = PNEU *
118 ;
119 ;

121 ;* TES'r DO~COUNTER-LOOP = 1SEC ?, NO- ~ GOTO CH~SET
122 ;

124 ;* YES- DELTAP: = PNEU-PALT *
~25 ;
126 ;
127 ;* 'llEST AT SNORKEL ?9 YES-~ GOTO PS3 128 ; PORT P2 ~IT6=1 ?
129 ;
130 ;* NO ~ 'rEST DIVER HAS ENTERED WATER
131 ;
132 ;* -~ TEST DELT~P ~80 ? . NO -~ GOTO PS3 133 ;
134 ;
135 ;* YES -~TEST DELTAP ~ 0.025BA~ ?~ -~ NO GOTO PS3 136 ;
137 ;
138 j*YES -~ SET S'~ATES AND FLAGS FOR SNORKEL-WO~K *

140 ;* AT SNOREEL - PORT P2 BIT6: -1 141 ;
142 ;
143 ;* PNULL: = PALT/49 WITH RO'rATE *
144 ;
145 ;
146 ;* PNEU~ = PNEU/4, WITH ROTATE *

148 ;
149 ;

151 ;* PALT: = PN~EU *
152 ;
153 ;
154 ;* SE'r DOWNC1: = 2 *
15~ ;
156 ;
157 ;
158 ;* Go~ro C~KSET *
159 ;
160 , ~ 4~ 3 ~x~x~x-~****~x~x~**~x-~x **
Program 2 ,* CHKSET
CHKSET 4 ;*
5 ,~
Pa~e 1 6 ,*
7 ;* ~HIS MAIN PROGR~I IS EXECUl'~D EVERY
8 ;* 0.5 SECONDS
9 ;* IN IT, THE RELEVANT VARIAB~ES, 10 ,* T~DERS AND GOUNTERS ARE ~P DATED ~ND (OR) RESET
11 ;* IF NECESSARY
12 ;* ALSO, AF~ER T~E A~OVE EAS ~EEN EXECUTED, A
13 ;* ~RANC~ IS ~fADE TO THE NEXT PROGRA~f ~0 PE
14 ;* EXECU~ED, RESULT~IG ~RO~i THE STATUS SET.
15 ;*
16 ;*
17 ;*
19 ;*
20 ;*
21 ,*
22 ;*
23 ~-X~ff~Xxx-x-x-x**~ " ~ xxx~xxxx-****-x-x*-~-~x-*
24 ;
25 ;
26 ; EQUATES
27 ;*-X-*-~***~*tx~H~x~H~x~*
28 , 29 ;
~0 9 31 ; VARIABLES
32 ;
33 ; PNEU EQU 62 34 ; PNULL -EQU -61 35 ; DEPT~ EQU 58 ; ACTUAL DIVING DEPTH
36 ; DEi~LXV EQU 57 ; MAX. DEPTH OF DIVE (VAREABLE) 37 ; DEMAXD EQ~ 56 ; ~X. DEPTH OE DIVE ~DISP~AY) 38 ; DEDEK EQU 5~ ; ACT~AD DECO DEPTH STAGE
39 ; DEDEK~f EQU 52 ; MAX. DECO DEPTH~STAGE
40 j BOTSEC EQU 47 ; BOTTOMT~E (SECONDS PART) 41 9 ~OT EQU 46 ; BOTTOMTI~E (MINUTES PART) 42 3 BOTZZ EQ~ 43 43 ; BOTZZS EQU 42 44 ; SFINTT EQU 41 45 ; SFISEC EQU 40 46 ; KEGELT EQ~ 3~ ; CONE TI~E (MINU~ES PART
47 ; XEGSEC EQU 38 ; CONE TIME ~SECONDS PART
48 ; DEKOTT EQU 37 49 ; DEKOTS EQU 36 50 ; DEKOT EQU 35 51 ; UI'DIVT EQU 34 52 ; DIVET EQU 33 53 ; SDEKOT EQU 31 ; S~M OF DECOTI~S
54 ; DIYETS EQU 32 Table 14 55 ; DOI~C1 EQU 27 ProgramO 56 ; DOWC30 EQU 26 ; DOWNCOUNTER FOR 30SEC
57 ; STATRG EQU 24 CHKSET 58 ;

PagP 2 60 ' SUBRO~TINES

62 ; SUB EQU XXXH FOR TEST IN ICE
63 ; SUBD EQU XXX~ FOR ~EST IN ICE
64 ;
65 ;
66 ; DIV8D EQU XXXH; 8 ~Y 8 DIVIDE, DIRECT
67 ; BDECOW EQU 380H; SUBR. DECO-VA~ES
68 ;
69 ;
7o ;
71 ; STATE~DENTS
72 ;~xxxxxxxxxxxxxxxx~xxxx 73 ;
74 ;
75 ;
76 GHKSET:
77 ;
78 ;
79 ;
80 ~ .
81 ;* qES~ AT SO~TW~RE-ERROR ?9 YES-~ COTO C~hK2 82 ; -~ STATRG BIT6=1 83 ;
84 ;
85 ;
86 SETO:
87 ;* NO~ DECREMENT DOW~COUN~E~ 1 SEC *
88 9o -- -89 ;
90 ;* TES~ O~T OF RANGE ?, YES-~ GOTO SET1 *
91;
92 ;
93 ;
94 ;
95 PGSET2:
96 ;* NO -~ ASCEN~ TIME WITHIN ZEROTIME PROVISIONS
97 ; -~ ~PD m : = TRUNC(~DEPTH+10)/20)~
.98 ;
99 ;* TEST AT ZEROT~Dn E ?, YES-~ GOTO SET3 100 ; -~ FLAG F1=1 ?
101 ;
102 ;* NO ~ DETERI~INE ALL DECO-VALUES NEEDED *
103; ~? PREPARE AND CALL SUBR BDECOW
104 ; ~ DEKOT: = (DEKOT OF DEI~
105 ; -~ DEDEK: = DEDEKM
1 o6 ; - ~ STORE S~I OF DEKOTIMES IN SDEKOT
107 ;
108 ;* IRACK ASCENT TI~E OUTSIDE ZEROTI~E
109 ; ~PDIV~: = UPDIVT + (SUM 0~ DECOTIMES) - 95 ~ ~ 5 Table 14 110 ;
gr 112 , ~S~T 113 SET3:
p 3 114 ;* TEST AT S~RFACE ?, NO-~ GOTO SET2 *
g 115 ; -~ STATRG ~ITU=1 ?
116 ;
117 NXSET1:
118 ;* YES~ TEST AT SURFACEIN~ERVAL ~, NO-~ GOTO SET4 119 ; - STATRG BIT3=1 ?
120 ;
121 NXSET2:
122 ;* TRACK S~RFACEINTERVAL,TI~E *
123 ;* YES-~ TEST SFISEC=120 ?, NO GOI'O SET4 *
124 ~
125 ;
126 ;* YES- SFINTT: = SFINTT~1. SFISEC: =O *

128 ;
129 9 * GOTO SET3 *
130 ;
131 ;
132 ;
133 SET5:
134 ;* SFISEC: SFISEC~1 *
135 ;
136 ;* GOTO SET4 *
137 ;
138 ;
139 ;
140 SET1:
141 ;* SET ALL FOR OUT OF RANGE *
142 ;
143 ~* SET STATES AND FLAGS AT ZERO *
144 ;
145 ;* PREPARE FOR DISPLAY *
146 ;
147 ;
148 ;* DETERMINE ACT~AL DEPTH *
149 ; - DEPT~: = PNE~-PNULL
150 ;
151 ;* ~EST DIVER LEAVING T~E WATER ?, NO ~ *
152 9 * - GOTO SET2 *
153 ;' TEST DEP~ ~= O ?

155 ;
156 ;* DEP~I: = O *
157 ;
158 ;
159 ;
160 ;
161 SET2:
162 ;* TRACK DIVETI~E *
163 ;* TEST ~ nETS = 120 ?, NO GOTO SE~6 164 ;

.- 96~ 3 Table 14 165 ;* YES- DIVET: = DIVET+1~ DIVETS: ~O *
P g:r : 167 CHKSET 168 ;* GOTO SET7 *
page 4 170 171;
172 SET6:
173 ;* DIVETS =DIVETS+1 *

175;
176;
177;
178 SET7:
179 ;* TEST O~T OF RANGE ? ~ YES--~ CrOTO DISRLY
180 ; - PORT2 E3IT7=1 ?
181;
182;
183;
184 SET4:
185 ; ~ TE;)T AT CORRECTION~3OTTOMTINE ?, NO GOTO SET8 186 ; ~~ STATRG BIT4=1 7 187;
188 NXSET4:
189 ;* YES-> TRACK CORRECTION ~30TTOMTI~IE *
190 ;* TEST :13OTZZS = 120 ?~ NO GOTO SET9 *
191;
192 PGSET1:
193 ;* YES- :3OTZZ: = ~3OTZZ+1, :BOTZZS: =O *
1~4 195 ~
196 ; * GOTO SET8 *
197;
198;
199; . .
200 SET9:
201 ; * :13OTZZS: =BOTZZS~1 *

203;
204;
- 205;
206 SET8:
207 ~* TEST AT DI~P ?, NO--~r GOTO SEr~l O *
208; _~ STArrRG 13IT2=1 ?
po9;
210 N~CSET5:
211 ; * YES--> TRACK CORRECTION 130TTOlilTll~lE *
212 ;* TEST XEGSEC = 120 ?~ NO GOTO SET11 *
213;
214 ;* YES-- KEGELT: = KEGELT~ EGSEC: =O *

216;
217 ;* GOTO SET12 218;
219;

~ 97 ~

TABLÆ 14 220 ~
221 SET11:
Program: 222 ;* KEGSEC: =KÆGSEC+1 *
CHKSET 223 ;
Page 5 224 ~
226 ;
227 SET12:
228 ;* DEC~ENT DOWNCO~NTER--~qSEG *
229 ; - DOWC30: = DOWC301Y1 230 ;

232 ;
233 SET10:
234 ;* TEST AT DECO~RESSING ?9 NO-~ GOTO CEEKl *
235 ; ~ PORT2 BIT5=1 ?
236 ;
237 NXSET6:
238 ;* YES-~ ACQUIRE DECOTI~E TOTAL AND CO~T DO~ THÆ
239 ;* DECOT~E 0~ THE RELEVA~T DECO DEPTH STAGE
240 ;* TÆST DÆKOTS = 120 ?, NO GOTO SET13 241 ;
242 ;
243 PGSÆT3:
244 i* YES-~ DÆKOTT: = DEKOrTT+1, DEKOTS: =0~ DEKOT: = DEKOrr~1 246 ;
247 ;* GOTO SET14 *
24~ ;
249 ;
25Q ;
251 SET13:
252 ;* DÆKOTS: =DEKOT$~1 *
252 ;
254 ;
255 ;
256 ;
257 SET14:
258 ;* DECREASE ASCENT TIME DURING DECO~IPRESSION BY THE *
259 ;* TOTAL TIME DECO~;PRESSED (DEKOTT) *
260 ; _ ~PDIVT~ = UPDIVT+SDEKOr~-DEKOl~T
261 ;

263 ;
264 ;
265 ;
266 ;
267 CHEK1:
268 ;* TÆST TEÆ STATÆS ~ND AS A RES~T *
269 ;* -~ GOTO NEXT PROGRAM *
270 ;
271 ;
272 ;
273 ;
274 CHEK2:

D~ D3 '~able 1 4 Program CHKSET

275 ;* AT SOFTWARE-ERROR *
276 ;* SET ALL FOR SO~TWARE-ERROR *
277 ;
278 ;* SET STATES AND FI~GS AT ZERO *
279 ;
280 ;
281 ;* PREPARE FOR DISPLAY *
282 ;
283 ;
284 ;* GOTO DISPLY
285 ;
286 ;
287 ;

USER SY~OLS
CEEK1 0000 CHEK2 0000 CEKSEI' 0000 NXSET1 0000 NXSET2 0000 ~SET

_ 99 ~ t-~

Table 1~ 1 ;~X-XXXX~-XXXXXXXX-X--XXXXX~X~-XXXX*-XX-***-X*,~XXX~x-~X~H~*-x~-2 ;*
Program: 3 ;* SURFACE REGION
SURFAC 4 ;*
Pag~ 1 6 ,x-~
7 ;* THIS MAIN PROGRAM IS EXEC~TED AS A RESULT OF THE
8 ;* STATUS AT SURFACE AND PERFORiMS T~E FOLLO'.~ING:
9 ;*
10 ;* DETECTION WHETHER T~E DlVER
11 ;*
12 ;* A) IS SNORKELLING, I.E. IS IN T~E WATER, 13 ;* BUT R~5AINS NEAR THE SURFACE
14 ;* -~
15 ;* DEPTH: = (PNE~-P~LL) 16 ;*
17 ;* ~) LEAVES TUE SURFACE ~Y CHANGING
18 ;* TO DIVING
19 ;* STATUS: = DIVE
20 7*
21 ;* C) LEAVES THE WATER A~D THEREFORE DIR~CTLY
22 ;* CHANGES TEE GAIN OF 'l'~h' ADC.
23 ;* FLAG: = NOT SNORKEL
24 ,*
~5 ;*
26 ;* D) IS IN A SURFACE
27 ;* INTERVAL -S
28 ;* CALL SUBROUTINE, FOR DETE~IINATION OF
29 ;* THE REP~ GROUP A~ END OF SURFA Æ
3o ;x- IN~RVAL
31 ;*
32 ;* E) HAS REACHED REP. GRO~P lOtl _~
33 ;* FLAG: = NOT SURFACEINTERVAL
34 ;* ~ _ 35 ,* NECESSAR~ INITIA~ISATION BY
3~ ;~ REST~RT
37 ;*
38 ;* SURFACEINTERVA~TIMER -?SFINTT: =O
39 ;* DITTO -~SFISEC: =O
40 ;* NO~ SURFACEINTERVAL -~STATRG ~IT3: =0 41 9* AT SURFACE -~STATRG LITO: =1 42 ;* ACTHAL REP. GROUP -~RPGRU~-. = O
43 .*
44 ;* NOTE: CYC~IC STARTING OF T~IS PROGRA~I
45 ;* EVERY 0.5 secD
~6 ;*
47 ;*
48 ;
49 ;*
5o ;*
51 ;*
52 ;*
53 ;*xxxxxx-~xxxxxx*xxx*******~xxxx-x-xxxxxxxxxx~xxxxxxx******
54 ;

- 100 ~ 3 Table 15 55 ;
Program: 57 ~*xxxxxxxQ~***~Xx-x*
SU~FAC 58 ;
Page 2 60 , VARIABLES
61 g 62 ; PNEU EQU 62 63 ; PN~LL EQ~ 61 64 ; DEPT~ EQU 58 ;ACTUAL DEPTE
65 ; RPGRUP EQU 50 ;ACTUAL REP.GROUP
66 ; SFINT~ EQU 41 ;SU~FACEINTERVAL-T~E~(MrNUTES
67 ; SFISEC EQU 40 ;SURFACEINTERVAL~T~ER~SECONDS
68 ; STATRG EQU 24 ~STATUS REGISTER
69 ;
7o ;
71 ; SUBROUTINES
72 i 73 ; SUB EQU XXXH, 74 ; S~BD EQU XXXH~
75 ; ~RPGSF EQU XXXE; SUBROUTINE FOR RPGRUP DE~ER-76 ; ; MINATION AT T~E SURFACE
77 ;
78 ; STATE~1ENTS
79 ;xxxx--~x-**~xxxxx-x-~x~*
80 ;
81 ;
82 ;
83 ;
84 S~RFAC
85 ;
86 ;
87 ;* TEST AT SNORKEL ?, NO -~ GOTO SF2 *
88 ; --89 , 90 ~* YES-~ C011P~TE ACTUAL DEPTH *
91 ;

93 7* TEST DnER LEAVING TUE WATER ?, YES-~ GOTO S~1 *
9~ ;* TEST DEP~H ~ - O ? *
95 ;
96 ~
97 ;* NO-~ TEST DEPT~ ~ 1.5M ?, NO-~ GOTO SF2 *
98 ;
99 ;
100 ;* YES-~ DIVER DIVING -~ SET STATES *
101 ;
102 ~* AT DlV~ -~ STATRG ~IT1: =1 103 ;
104 ;
105 ;* NOT S~ACE -~ STATRG BITO: =O *
106 ;
107 ;
108 ;* GOTO DISPLY *
109 ;

Table 15 110 ;
Program ~11 ;
SURFAC 113 ~* SET FOR SURFACE WORK ~
Page 3 114 ,* NOT SNORKEL - PORT P2 BIT6: =0 *
116 ;
117 ;* PALT: = PALT*4, MATCE PRESSURE TO GAIN 4.
118 ;
119 ;
120 ;* DEPTH: = O *
121 ;
122 ;
123 ;
124 SF2:
125 ;* TES~ AT S~RFACE INTERVAL ?, NO -~ GOTO DISPLY
126 ;
127 ;
128 ;* YES- DETERi~NE ACT~AL REP. GRO~P AT THE END 0~ *
129 ;* T~E (RPGR~P) AND 'l'~ SURFACEINTERVAI-T~IE *
130 ;
131 ;
132 ;* TES~ REP. GRO~P AT END OF SURFACE-IN~ERVAL = O ?. *
133 ;* NO- GOTO DISPLY *
134 ;
135 ;
136 ;* YES-~ SE~ NOT SUR~ACE~TERVAL -~ Sl`A~RG ~IT3: =0 *
137 ;
138 ;
139 ;* GOIO DISPLY *
140 ;
141 ;

ASSE~LY CO~IPLETE. NO ERRORS

- 102 ~

Table 16 1 ,****~*~*~ e~ ~****~***
2 ~*
Pro~ram: 3 ;* DnE
DIVE 4 ;*
Pa&e 1 5 '~ ~ - ~~ ~ ~~
7 ;* ~S MAIN PROGRAM IS EXECUTED AS A RESU1T OF TUE
a ; * AT DIVE STATUS AND CARRIES WT:
9 ;*
10 ;* 1 DETE~NATION OE 'l'~E BOTTOMT~IE AND THE
11 ;* VARIO~S "DEPT~S"
12 ;*
13 ;* 2 DETECTION OE WHETUER THE DIVh'R.
14 7*
15 ;* A) IS DIVING, I.E. IS S ~I~NG DO~niARDS
16 ;* OR HORIZONTALLY~ IF THE DIVER IS
17 ;* MOVING TOWARD THE SURFACE -~
18 ;* STATUS: = DIVEUP
19 ;*
20 ;*
21 ;* B) OBTAINS A GAIN IN TIME ~IE ~E~R~
22 ;* '~0 ~OTTOM T~IE AS A RESULT OE STEP-23 9 * BY~STEP DESCENT -24 ;* BOTTOMTIME: ~ ADDED TIME
25 ;*
26 ;* C) SURFACES ON THE ZEROTI~E LIMIT AND
27 ;* I~EDIA'rELY DIVES AGAIN TO THE
28 ;* PREVIOUS ~XI~1 DIVE DEPTH -~
29 ;* -` ~ORRECTION OF 'l'~E CONSEQUEN'r 3Q ;* INCORRECT BOTT~ITI~
31 ;* BOTTOMTIME: ~ (ZRROTIME 0~ THE MAXIMmM
32 ;* DIVE DEPT~3+(BOTTOMT~IE
33 ;* ADDITION) 3~ ~*
35 9'~ D3 EAS EXCEEDED THE ZEROTIMæ
36 ;* LIMI'r. -~
37 ;* FLAG: = NOT ZEROTIME-DlV~
38 ;*
39 ;*
40 ;* NECESS~RY INITIALISATION BY
41 ;~ RESTART
42 ;*
43 ;* AT ZEROTI~ ~ DIVE -` ELAG F1: =1 44 ;* NOT CORRECTION~BOTTOMTIME ~~ STATRG` BIT6: =O
45 ;* ~OT DIVE -_ STATRG BIT1 r =O
46 ;* DEPTH STAGE = 1ZM -~ DEST = 24 ~7 ~*
48 ;* NOTE CYCLIC STARTING O~ I~IS PROGRAM
49 ;* EVERY 005 SECo 5o ;*
51 ;*
52 ;x 53 ;~
54 ;*

~ 103 -rrable 16 55 9*
~rogram 57 -X-~*-X~H H~H~X~ * ~ ~,~ e--*--.----- ~ ~*~x-x x x x x ~-x ~--x-~**
DIVE 58;
~o .
Pa~e 2 60 7 EQUATES
61 ;xxxx-~ xxxxx--x 62 ;
63 ~
64 ; VARIABLES
65;
66; PNEU EQU 62 67 ; PNULL EQU 61 68 ; DELTAP EQU 5g 69; DEPTH EQU 58 ;ACr~UAL DEPTU OE DIVE
70 ; DEMAXV EQU 57 ;MAX~ DEPTU OF Dn E V~RIABLE) 71; DEM~LXD EQU 56 ;I~AX. DEPTE OF DIVE DISPLAY~
72 ~ DEsrr EQU 55 ; ACTUAL DEPrnU STAGE
73 ; DESTK EQU 54 ; CORRECTION-DEPT~ STAGE
74; RPGRUP EQU 49 75; BOTSEC EQU 48 ;BOrrTOMT~ E(S3CONDS PART) 76; BOT EQU 47 ;~OTTOMT~E(I~INUTES PART~
77; BOIK EQU 46 ;CORRECTION-BOTTO~T~5E (Z~ROrrIME
78 ~ ;OF D~LEY) 79 ; BOTZZ EQU 45 ;BOrrTOMT~`1E ADM TION
80 ; KEGELT EQU 42 ;CONE rrI~E (MINUIES~T~rER) 81 ; XEGSEC EQU 41 ;CONE TIME (SECONDS-TIMER) 82; DOWC30 EQU 29 ;DOWNCOUNTER FOR 30SEC
83;
84; SUBROUTINES
85;
86 ; STATRG EQU 24 87; SUB EQU XXXE
8B; S~BD EQU XXXH
89; BRPGUW EQU XXXH;SUBR~ FOR DETE~MINATION OF
;~PGRUP UNDER WATER
91 ; 3ZZH EQU XXXH;SUBR. FOR DET~ OF A~DED-rrIME
92; BZT EQU XXXH;SUBR. FOR DET~ OF ~EROTIME
93 ; BDEST EQU XXXE;SUBR. FOR DET. OF DEPr~H-STAGE
94; BDESTN EQU XXXH;SUBR~ FOR DETo OF NEXT GREATER
DEP~E--SrrAGE
96;
97;
98 ; SIlArrE~DENrrS
99 9XXXXXXXXXXXXXX~XXXXXXX
100;
101;
102;
103;

105;
10~;
107;
108 ;* CO~UTE ACTUAL DEPTE *
109; DEPTH: =(PN~ PN~LL *

- 104~ 9~P~3 Table 16110;

Progra 112 ,* TEST DELTAP C0 ?~ YES-~i GOTO DIVE1 *
DIVE 113 ; - DELTAP = (P~ ~ -PA~T) Pag_ 3 115 ,* NO ~ r~RAC~ MAX. DEPTHS IP NECESSARY
116;
117;
118 ;* TEST DEPT~ ~ DEI~AXD ?~ NO-~ GOTO DIVE2 *
119 ;
120 ;* YES- DEli~ D: = DEPTE *
121 ;
122 ;
123;
124 DIVE2:
125 ;* TEST DEPTH > DEMAXV ?, NO-7 GOTO DIVE3 *
126;
127 ;* YES- DE~5AXV: = DEPT~ *
128 ;
129 ;
130 ;
131 DIVE3:
132 ;* CO~PUTE STEP-BY-STEP DESCENT AND BOTTOMTI~E *
133 ;* TIME GAIN~ IP POSSIBLE *
134 ;
135;
136 ;* TEST ACTUAL DEPT~ STAGE EXCEEDED ?~ NO-~
137 ;* ~ GOTO DIVE4 138 ;
139 ;* YES-~ DETEEMINE REP~ GROUP WITU T~E ACTUAL DEPT~
140 ;* STAGE AND 'l'~E BOTTOMTI~E IN TEE REPETITIVE TAP~E
141; -~ PREPARE A~D CALL SUBR~ DRPGIJW
142;
143 ;* DET ~ ~INE NEXT GREATER DEPTH STAGE WIT~ T~E
144 ;* ACTUAL DEPTa STAGE AND 'l'hE REPETITIVE TABLE
145 ; -~ PREPARE AND CAL~ SUBR~ DESr~N.
146 ;
147 ;* DErnE~INE T~E ADD~D TI~IE(ZZU) WIr~ E (NE~I) ACr~AL
148 ;* DEPTH STAGE AND rL~E REP~ GRO~P IN TUE REPETITIVE
149 ;* TABLE
150; -~ PREPARE AND CAI,L SIJBR. BZZU
151;
152 ;* TEST ADDED-TIME(ZZ~ ~ BOTTOMTI~E ?~ YES-~
153 ;* ~ &OTO DIVE4 154 ~
155 ;* 1~ BOTTOMTI~5E: = ADDED-Tll~qE
156;
157 ;
158 9 "-` 7 160 ;* :BOTTC~;LTl~IE: --:BOTTOI~TIMEtO.5SEC *
161;
162;
163 ;* q~EST BOTTC~iTIME = 255Mll~ ? ~ NO-- &OTO DIVE5 164;

Table 16 165 ;* YES-' ~ ~ POSSIBLE BOT~OMT~5E EXCEEDED -~
Program: 167 9'~ SET FOR O~T OF RANGE.
DIVE 168 ; -~ OUT OF RANGE -~ PORT2 ~IT7=1 Page 4 170 , - NOT DIVE - STATRG BIT1=0 171 3* GOTO DISPLY *
172 , 173 ;
174 ;
175 DlV~'5 176 ;* CORRECTION OF 'l'~E INCORRECT BOTTOMT~E DUE TO
177 ;* SHORT-T~IE SURFACING
17B ;
179 ;
180 ;* TEST ACTUAL DEPTH STAGE = CORRECTION DEPTH STAGE ?
181 ;* NO-~ GOTO DIVE6 182 ;
183 ;* YES-~ TEST ((ZEROTIME OF THE rLLx DIVE DEPT~) ~
184 ;* (BOTTO~TIME ADDED-TI~E)) ~ ~OTTOIYITIME ?
185 ;* YES-~ GOTO DIVE7 186 ;
187 ;* NO-~ ~OTTOMT~5E: =((ZEROT~IE OF 'l'~E MAX. DIVE DEPTH~+
188 ;* (BOTTO~ITIME ADDED-TI~E~) 189 ;
190 ;
191 ;

193 ;* SET NOT CORRECTION-BOTTOMTIME *
194 ;~ STATRG BIT4: =0 *
195 ;
196 ;
197 ;* RESET T~E BOTTOMTIME ADDED-TIME IN *
198 ;* MINUTES AND SECONDS: ~ O *
199 ;
200 ;* GOTO DIVE6 *
201 ;
202 ;
203 y 204 DIVE1:
205 ;* NO-~ DIVER ASC~DING *
206 ;
207 ;* BOTTOMTI~E: = BOTTOMTIME+0.5SEC
20~ ;
209 ;* SET STATES *
210 9* NOT DIVE -~ STATRG BIT1: =0 *
211 ;* AT DIVEUP ~~ STATRG BIT2s =1 *
212 i 213 ;* SET TIME~S AND COUNTERS *
214 ;* CONE T~5E: =0, IN SECONDS AND M~CNUTES TI~æRS *
215 ;* DO~NCO~NTER 30SEC: =61 *
216 ;
217 ;
218 ;
219 DIVE5:

- 106 ~ r~ ~

Table 16 220 ;* TEST AT ZEROT~E-DIVE ?~ NO~ GOTO DISPLY *
Progr 222 ,* YES-~ DETER~ilNE ZEROT~lE OF 'l'~E MAX DIVE DEPTE
DIVE 223 ; ~ PREPARE AND CALL SUBR. BZT
Page 5 2245 , 226 ;* TEST AT ZEROT~E-DIVE ? 9 NO-~ GOTO DISPLY
227 ;
228 ;* YES ~ *
229 ;* TEST BOTTO~TIME ~ ZEROTI~E ?~ NO~ GOTO DISPLY
230 ;
231 ;* YES~ CORRECTION-PO~TOMTI~E: = BOTTOMT~E
232 ;
233 ;
234 ~* CONVERSION OF 'l'EE BOTTOMT~E OE THE r~. DEPTE *
235 ;* (VARIABLE) TO THE ACTUAL DEPTH *
236 ;
237 ;* DETERM~E REP. GROUP WITE TEE ~X. DEPTE AND *
238 ;* THE ZEROT~E *
239 ; -~ PRE~ARE AND CALL SUBR. BRPGUW *
240 ;
241 ;* DETERMINE BOTTOMT~IE WITH THE REP. GROUP AND *
242 ;* ACTUAL DEPTH.
243 ; -3 PREPARE AND CALL SUBR. BZZU
244 ;
245 ;* DET ~INE ZEROTI~E OF T~E ACTUAL DEPTH *
246 ; -~ PREPARE AND CALL SUBR. BZT
247 ;
248 ;
249 ;* TEST BOTTOMT~E ~ ZEROT~IE ?, YES~ GOTO DIVE8 *
250 ;
251 ;* NO-~ SET FOR CORRECTION *
252 ;
253 ;* AT CORRECTION ~OTTOMTIME -~ STATRG BIT4,o =1 *
254 ;* I~LX. DEPTH (VART-ARLE): = ACTUAL DEPT~ *
255 ;* CORRECTION DEPTH-STAGE: = ACTUAL DEPTE S~AGE *
256 ;* DEq~ INE (NEW) ACTU~L DEP~H-STAGE WITH THE *
257 ;* ACT~AL DEPTH IN THE DECO TABLE *
258 ; -~ PREPARE AND ChLL S~BR~ ~DEST
259 ;
260 ;* GOTO DISPLY *
261 ;
262 ;
263 ;
264 DIVE8:
265 ;* SET NOT ZEROT~33-DIVE -~ FT,AG F1: = O
266 ;
267 ;* GOTO DXSPLY *
268 ;
269 ;

USER SYI~OLS

DI~E8 OOOQ

- 107 ~ 3 Table 1~ *-~**~**~x-~*~ ~x~ xx~*~**-x~ ~x-~**~
2 ;*
Program 3 ;* DIV~UP
DIV~UP4 ;*
Page 16 ,*
7 ;* THIS MAIN PROGRA~I IS EXECUTED AS A RESnLT OF THE
8 ;* STATUS AT DIVEUP AND PERFOR~'S THE FOLLO'~'ING
9 ,* FUNCTIONS:
10 5*
11 ;* 1~ DETERr~NATION OF 'l'~` ACTUAL DET~TH ~ND
12 ;* TRACKING OF r~E TEI~'~PORARY ~OTrrOMT~E.
13 ;*
14 ;*
15 ;* 2. CYCLIC SETTING OF ASCENT CONES AND
16 ;* CHEC N NG, WHETHER rrHE DIVER IS WITHIN
17 ;* T~E T~ E AND PRESSURE LIMITS OF 'l'~ESE
18 ;* ASCENT CONES.
19 ;* I.E.:
20 ;* DETECTION WHET Æ R THE DIVER IS NO LONGER
21 ;* ASCENDING AS DEFINED;
22 ;*
23 ;* A) ~ECAUSE HE REAC Æ S THE S~RFACE
24 ;* REGION -~
25 ;* STATUS: = SURFACE
26 ;*
27 ;* ~) ~ECAUSE HE HAS REACHED T~E LOl~EST DECO-STAGE
28 ;* -~ STATUS: = DECOMPRESSION
29 ;*
30 ;~ C) ~ECA~SE HE CHANGES TO DIVING, PECAUSE THE
31 ;* ASCENr~-RATE IS ~ 8~IN
32 ~
33 ;*
34 ;* 3, DETECTION W~ET~h~ THE DlVE~:
35 ;*
36 ;* A) IS ASCENDING ON THE ZEROTIME LIMIT -~
37 ;* THROUGH THIS A STEP-~Y-Sl~ ASCENT
38 ;* IS MADE POSSI3LE.
39 ;* I.E. CONVERSION OF 'l'~ ~OTTOMrr~E FROM
40 ;* THE DEPTH, AT WHICH THE ASCENT ~EGAN~
41 ;* TO THE LOTTOMT~3 OF 'l'~ ACTUAL DEPTH.
42 ;* PREPARATION OF 'l'~h' CORRECTION VAL~ES
43 ;* FOR A POSSIBLE CEU~GE TO
44 ;* DIVING.
45 ;*
46 ;* P) EXCEEDS THE ZEROT~E L~1IT -~
47 ;* FLAG: = NOT ZEROT~IED nE
48 ;*
49 ;* C) HAS DIVED ~ELOW THE DEPTE STAGE, 50 ;* IN WHICH r~E ASCENT WAS BEGUN
51 ;* _~
52 ;* STATUS: = DIVE
53 ;*
54 ;*

1 oa ~ 3 Table 1l 55 ;* NECESSARY INITIALISATION 3Y
ProgTr3m: 557 '* RESTART
DIVEUP 58 ;* AT ZEROTI~EDIVE ~~ FI~G F1: - 1 P e 2 59 ;* NOT DIV~U~ ~~ STATRG BIT2: =0 r3g 60 ;* NOT CORRECTION- BOTTOMT~E - ~ STATRG BIT4: =0 61 ;* CONE TI~IE ~~ KEGELT =O
62 ;* CONE TIME(SECONDS) ~~ KEGSEC =O
63 ;* DOWNCO~N'l'~H FOR 30SEC~ ~~ DOWC30 =61 64 ;* T~PORARY BOTTOMTI~E -~ TBT: =O
65 ;*
66 ;*
67 ;* NOTE CYCLIC STARTIN('r EVERY 0.5 SEC~
68 ;*
69 ;*
70 ; x 71 ;*
72 9*
73 ;*
74 ;*
75 ; *~x x x * x--~-~x x ~ x x x- x-x #~X~H~X~**~X ****~ X X X X ~X~* .~X-*~X-~ 4X-*-X~
76;
77;
78; EQUATES
79 ; -X~HH~**~Xi~X-**~ x x ~ x x x x-80;
81;
82;
83; VARIABLES
84;
85; PALT EQ~ 63 86; PNEU EQU 62 87; PNULL EQU 61 88; PALT30 EQU 60 B9; DELTAP EQU 59 90; DEPTE EQU 58 ;ACTUAL DIVE DEPTH
91 ; DEI~AXV EQ~ 57 ;~. Dn E DEPTE(VARIABLE) 92 ; DEST EQU 55 ;ACT~AL DEPTH-STAGE
93 ; DESTK EQU 54 ;CORRECTION-DEPTH-STAGE
94; DEDEK EQU 53 ;ACTUAL DECO DEPTH-STAGE
95; DEDE~M EQU 52 ;~I~X. DECO DEPTH-STAGE
96; RPGRUP EQU 49 97; BOTSEC EQU 48 ;BOTTOMT~E(SECONDS PART) 98; BOT EQU 47 ;BOT'rO~TIME(MINUTES PART~
99 ; 30TK EQU 46 ; CORR~CTION-30TTOMT~E
100 ;(~`iPORARY ~OT'I'OMT~5E) 101 ; KEGELT EQU 42 ;CONE TIME(MINUTES PART) 102; KEGSEC EQU 41 ;CONE T~1E(SECONDS PART) 1~3 3 l~T EQU 34 7 TEI~ORARY BOTTOMT~iE
104 9 DIVET EQU 33 ;DIVET~5E(MINUTES PART) 105; DIb'ETS EQU 32 ;DIVET~;E(SECONDS PART3 106; DOWC30 EQU 29 ;DOWNCO~NTER FOR /)SEC~
107 ; STATRG EQU 24 108 ;
109 ; SUBROUTINEN~

- 109~ 3 Table 17 110 111 ; SUB EQU XXX~
Program: 11 2 ; SUBD EQU XXXH
DIVEUP 113 ; ~RPGHW EQU XXXH; SUBR. TO DETERMI~E RPGRHP
114 ; UNDER WATER
Page 3 115 ; BZZU EQU XX~I; SUBR. TO DETERMINE ADDED-TIME
116 ; BZT EQU XXXH; SUBR. TO DErrERMlNE ZEROT~lE
117 ; BDEST EQU XXXH; SUBR. TO DETE~ E DEPTH-STAGE
118 ;
119 ;
120 ;
121 ; STAT~'~ TS
122 ;*~`;x~-**~*~xxx~x-x~xxx 123 ;
124 ;
125 ;
126 ;
127 DIVE~P:
128 ;
129 ;
130 ;
131 ;* CO~PUTE ACTUA~ DEPTH *
132 ; IEPTH: =(PNEU-PNULL) 133 ;
134 ;
135 ;* 'rEST (DOWNCOUNTER-30SEC~) = 60 ?~ NO-~ GOTO M VUP~
136 ;
137 ;* YES-~ SAVE PRESSURE AT BEGINNING OF ASCENT IN CONE
138 ; iYPALT30: =PALT
139 ;
140 ;
141 ;
142 DlVU~1 143 ;* TRACK T~PORARY-BOTTOMTIME ; COUNTING THE SECON~S
144 ;* AND MINUTES OF THE BOTTOMT~E AND CONE-TI~E.
145 ;* i~S~MM: = BOTSEC~KEGSEC
146 ;* ~TEST SUM = 120D
147 ;* -~NO-~ GOTO NEXDU1 148 ;* -~YES-~ TBT: = BOT-~KEGELT+1 149 ;* NEXDU1 -~ TBT: = BOT+KEGELrr 150 ;
151 ;
152 ;
153 ;* TEST AT ZEROT~ DIVE ?~ YES-~ GOTO M VUP2 *
154 ;
155 ;* NO-~ TEST DEPT~ = DEDEKM ?, NO~ GOTO DIVUP4 *
~56 ;
157 ;* YES DECO~I~RESSION CO~NTDOWN BEGINS *
158 ;
159 ;* SET STATES *
160 ;* NOT DIVE~JP ~~ STATRG BIT2: =0 *
161 ;* AT DECOMPRESSION ~~ PORT2 BIT5: =1 *
162 ;* THROUGH PORT P2 LINE 5 (BIT5)~ AN LED IS LIT *
16~ ;* AT ZEROTI~E-DIVE ~~ ~LACr F1: =1 164 ;* SET DOl~COUNTER-30SEC: = 61 - 110~ ;3 Table 17 16'- , -~ DOWC30: =61 Program: 167 ;* GO~l~O DIspLy *
DrVEUP 168 ;
P ge 4 170 172 ;* TEST DEPTH ~= 0.5M ?, NO~ GOTO DI W P3 *
173 ;
174 ;* YES7~ DIVER IN SURFACE REGION *
175 ;
176 ;* SET STATES *
177 ;* NOT DIVEUP ~~ STATRG BIT2: =0 *
178 ;* AT SURFACE -~ STATRG BITO: =1 *
179 ;
180;* SET DIVETI~E: = 09 rN ~ JTES AND SECONDS *
181 ;
182 ;* GOTO DISPLY *
183 ;
184 ;
185 ;
186 DIVUP3:
187 ;* NO-, DETERMlINE ZEROT~E 0~ THE MAX. DrVE DEPTE.
188 ; ~ PREPARE AND CALL SUBR. 3ZT
189 ;
190 ;
191 ;* DETEEMINE REP. GRO~P WITH 'I'HE MAX. DIVE DEP'I~ AND *
192 ;* ~ E ZEROT~IE.
193 7 -~ PREPARE AND CALL SUBR~ BRPGUW
194 ;
195 ;
196 ;* TEST TEMPORARY-BOTTOMTI~E ~ ZEROTI~E ?, NO-~
197 ;* -~ GOTO DrWP4 198 ;
199 ;* YES-~ SAVE THE I~qPORAR~ ~OTTOMTIME AND
200 ;* INITIALISE FOR A NEW ASCENT CONE
201 ;
202 ;* CORRECTION-~OTTOMTIME: = T~ORARY BOTTOMT~ E
203 ;* CONE T~IE: =0~ IN SECONDS AND MINUTES T~DERS
204 ;* DO~NCOUNTER 30SEC~: = 61 *
205 ;
206 ;
207 ;* DETE~1INE BOTTO~T~E WITH ~E REPo GRO~P AND THE
208 ;* ACTUAL DEPTH
209 ; -> PREPARE AND CALL S~BR. PZZU
210 ;
211 ;* TEST BOTTOMT~fE' ZEROT~`IE ?, YES-~ GOTO DI-WP5 212 ;
213 ;* NO-~ SET FOR CORRECTION
214 ;
215 ;* AT CORRECTION-~OTTOMTI~E -~ STA~RG BIT4: =1 216 ;~ M~ . DrVE DEPT~ (VARIABLE): = ACT~AL DEPT~
217 ;* CORRECTION-DE?T~-STAGE: = ACTUAL DEPTE-STAGE
218 ;* DETE~IINE (NEW) ACT~A~ DEPT~-STAGE WITH TEE
219 ;* ACTUAL DEPTE IN THE DECO-TABLE

220 ; ~ Pl~PARE A~D CALL SUBR. BDEST
Program: 222 9 ~ GOTO DIVUP4 DIVE~P 223 ;
P ge 5 2~5 7 226 DIVUP5:
227 ;* SET NOT ZEROT~DIVE -~ FLAG F1: =0 *
228 ;
229 ;
230 ;
231 DIVUP4:
232 ;* TEST DIVED BELO'~ THE DEPTH-STAGE *
233 ;* W~ERE THE ASCENT WAS BEGUN ?, YES-~ *
234 ;~ -~ GOTO DIVUP6 *
235 ; -~ TEST DEPTH ~ DEST ?
236 , 237 ;* NO-~ TEST DO'^~NCOUN'~R 30SEC. ?, NO? GOTO DISPLY
238 ; -~ TEST DOWC30 = O ?
239 ;
240 ;* TEST IS ASC~-RATE AT LEAST 8M/l~rrN ?, 241 ;* I.E. TEST ASCENTRATE=0.4 BAR/30SEC ?9 YES ~ GOTO DIVUP6 242 ; ~ TEST (PALT30 * 0.4BAR) ~ PNEU ?
243 ;
244 ;* NO-~ DIVER STILL IN ASCENT CONE *
245 ;* SET (DOl~lNCOUNTER 30SEC.): =61 *
246 ;
247 ;* GOTO DISPLY *
248 ;
249 ;
250 ;
251 DIVUP6:
252 ;* DIVER ~AS CE~GED TO DIVING *
253 ;
254 9~* SET T~D5RS *
255 ;
256 ;* ~OTTOMT~E: = BOTTOMTI~E~CONE-T~IE: WUILE THE SECONDS
257 ;* AND ~UTES OF THE BOTTOM TIME AND CONE T~E WILL ~E
258 ;* COUNTED: -~ S~: = LOTSEC+KEGSEC
259 ;* -~ TEST SUM = 120D ?
260 ;* NO~ GOI'O NEXDU2 261 ;* YES-~ BOT: ~ ~OT*KEGELT*l 262 ,* NEXDU2~ T: - BOT+KEGELT
263 ;
264 ; ~ TEST LOT ~ 255 ?, -~YES GO~ONEXDU3 265 ;
266 ;
267 ;* CONE T~IE = 00 IN SECONDS AND ~NUTES T~ERS *
268 ;*
269 ;* SET STATES *
270 ;
271 ;* NOT DIVEUP - STATRG BIT2: =0 *
272 ;* AT DIVE - STATRG BITl. =l *
273 ;
274 ;* GOTO M SPLY

Tabl ~ 275 ;
Program: 2~7 ~
DIVE~JP 278 NEXDU3:
P g 6 279 ;* I`'~X~J~ POSSILLE ~OTTO~ ~IE EXCEEDED
280 ,* SET EOR OUT OE RANGE -~ PORT2 3IT7: _1 282 ;* GOTO DISPLY *
283 ;
284 ;
285 ;

USER S~BOLS
DIV~UP 0000 DIVUP1 0000 DIV~P2 0000 DIVUP3 0000 DIV~P4 0000 DIVUP
ASSEI~B~Y COI~iPLETE. NO ERRORS

Table 18 1 ;*******~xxxx~x-~*~x~-x-x~xxx~xxxxx~H~x-xx~x-x-x*-~x-x~
Pr 2 ;*
ogram: 3 ;* DECO
DE50 4 9 *
Pag~ 1 5 ~
7 ;* ~HIS PROGRA~. IS EXECUTED AS A RESULT OE TEE DECO
8 ;* STATUS AND PERFORMS THE FOLLO~ING FUNCTIONS:
9 7*
10 ;* 1. DETER~IINATION OF ~E ACTUAL DEPTH .
11 ;*
12 ;* 2. DETECTION IF l~E DIVER DOES NOT DECO~li'RESS
13 ;* AS PRESCRIBED.
14 ;*
15 ;* A) IF HE DIVES 3M BEL~W THE ~LX. DECO
16 ;* DEPTH STAGE.
17 ;* -~ STATUS: = DIVE
18 ;*
19 ;* B) IF HE EN~ERS THE SURFACE REGION D~RING
20 ;* THE DECO-CO~NTDOWN, 21 ;* I.E. DOES NOT COMPLETE DECOMPRESSION
22 ;* -~ STATUS: = OUT OF RANGE
23 ;*
24 ;* 3. DETECTION, WHE~IER THE DIVER RETURNS TO THE
25 ;* SURFACE REGION WITHIN 30 SECONDS AFTER
26 9* C~IPLETION OF DECOMPRESSION.
27 ;* -~ STATUS: - SURFACE
28 ,* IF THE DIVER DOES NOT REACH l~ SURFACE
29 ;* WITHIN 30 SECONDS.
30 ;* - STATUS: = DIVE
31 ;*
32 ;* 4, DETER~iINATION OF TlIE NEXT HIG~ER DECO 3EPT~
33 ;* STAGE AND l'~E ASSOCIATED DECO TIME. IF THE
34 ;* PRESENT DECO-TIME HAS REACHED ZERO AND A
35 ;* NEXTL~IGHER DECO DEPTH STAGE EXISTSo 36 ;*
37 ;* OTHERWISE -~
38 ;* DECOMPRESSION COMPLETED AS PRESCRIBED.
39 ;* - FLAG. - DECO END
4o ;*
41 ~* 5. IF DECO~PRESSION IS C~PLETED AS PRESCRIBED, 42 ;* THE REP. GROUP OF THE CO~LETED DIVE IS
43 ;* DETER~IINED AND INITIALISATION IS CARRIED
44 7* EOR A NEW DIV~.
45 ;*
46 ;*
47 ;*
48 ;* NECESSARY FIRST INITIALISATION IY
49 ;* RESTART
5o ;*
51 ;* AT SURFACE - STATRG BITO. =1 52 ;* NOT DIVE - STATRG BIT1: =0 53 ;* NOT DlV~U~ - STATRG BIT2: =0 54 ;* NOT DECO-END - STATRG BIT5: =0 - 114 ~ 3 Table 18 55 ;* NOT SUR~ACEINTERVAL -~ STATRG ~IT3: =0 P~ogra~ 5 ; NOT DECOMPRESSION -~ PORT2 ~IT5: =0 57 ;* NOT OUT OE RANGE -$ PORT2 BIT6: =0 DECO 58 ;*
P e 2 59 ;* DO'~INCOUNTER -30SEC ~DOWC30: -60 60 ;* DO~NCOUNTER ~ IIN -~DO~IC1M: =120 61 ;* DECOT~DE-TOTAL -~DEKOTT: =O
62 ;* DECOTI~SE -~DEKOT : =O
63 ;* ~iX. DECO-DEPT~-STAGE -SDEDEKM:=O
64 ;* DECO DEPTH STAGE -5DEDEK : =O
65 ,*
66 ;*
67 ;* NOTE: CYCLIC STARTING EVERY 0~5 SEC.
6~ ;*
69 ;*
70 ;* - - - --- ---------------71 i*
72 ;*
73 ;*
74 ;*
75 ;**~ xxxxxxxxxxxx-x~**-~x-**~x~-xxxx~x~****~ X~X~X~H~X
76 ;
77 ;
78 ; EQ~ATES
79 ;~x-~****~XjH~X~**

81 ;
82 ; VARIABLES
83 ;
84 ; PALT EQU 63 85 ; PNE~ EQ~ 62 86 ; PNUL~ EQU 61 87 ; PALT30 EQU 60 88 ; DELTAP EQU 59 ag ; DEPTH EQU 58 ;AcTuAL DEPTH -- ---- ---90 ; DEMAXV EQU 57 ;~1LX. D n E DEPTH(VARIAB~E) 91 ; DEST EQ~ 55 ;ACTUAL D~PTH STAGE
92 ; DEDE~ EQU 53 ;ACTUAL DECO-DEPIH-ST~GE
93 ; DEDEKM EQU 52 ;~SAX. DECU-DEP~H STAGE
94 ; RPGR~P EQU 50 95 ; BOTSEC EQU 48 ;~OTTOMTIME SECONDS~PAR~
96 ; ~OT EQ~ 46 ;~OTTOMTIME MINUTES-PARI
97 ; ~OTK EQU 45 ;CORRECTION-~OTTO~IT~SE (TE~SPO-38 ~ ;-RARY LOTTOMTIME) 99 ; DEKOTT EQU 37 ; DECOTI~ ~ TOTAL
100 ; DEKOTS EQ~ 36 ;DECOTIME IN SECONDS
101 ; DE~OT EQU 35 ;DECOTI~E
102 ; DOWC30 EQU 26 ;DOWNCOUN~ER EOR 30SEC

104 , 105 ; SUBROUTINES

107 ; SUB EQU XXXH
108 ; SUBD EQU XXXE
109 ; BDEKOT EQU XXXH :SUBR~ TO DETE~IINE DECOT~iE

- 115 ~ Q ~3 Table 18 110 ; ~RPDEC EQU XXXH;SUBR. TO DET. REPo GROUPS
Program: 112 ;'~H~N ZEROT~IE EXCEEDF~
DECO 113 ;
Page 3 114, 116 ; STATEMENTS
1 1 7 ~ x -~*~ *~ **
118;
119 ?
120;
121;
122 DECO:
123;
124;
125 ;
126 ;* DETER~iINE AC'~UAL DEP'rE
127 ;* - DEPT~: = PNEU-PNnl~
128;
129;
130 ;* TEST HAS DIVER DIVED 3M ~ELOW 'nHE ~LX. DECO *
131 ;* DEPTE-STAGE ?, NO-~ GOTO DEK01 132 ; -~ TEST DEPTH ~ (DEDEK~I+3M) 134 ;* YES~~ M VER YAS C~U~IGE TO DIVE *
135 ;
136 ;* SET T~ERS *
137 ;
138 ,* ~O'~TOMTIME: = ~OTTOM'rIME~('rOTAL TIME DECOl~ ESSED) 139 ;* IN WHICH THE SECONDS AND MI~TES OF 'l~E ~OTTOMTIrE
140 ;* THE TOTA1 DECOMPRESSED TIME WILL ~E CObNTED
141 ;* -~ SUM = POTSEC~DEKOTS
142 ;* -~ TEST S~M = 120D ?, 143 ;* NO -~ GOTO ~E~ECO
144 ;* YES-~ ~OT: = ~OT+DEKOTT+1 145 ;* NEDECO ~ ~o'r: = ~OT+DEKOTT
1~6 ;
147 ;* DECOTIME~TOT~ O ~ IN SE~O~S A~D I~nr~E5 T~nE~S
148 ;
149 ;* SEr NOT ZEROTIMEDIVE -~ FLAG Fl = O
150 ;
151 ;
152 ;
- 153 DEKo6:
154 ;* SET STATES *
155 ;
156 ,* NOT DECOMPRESSION -> PORT2 BIT5: =0 157 ;* AT DIVE - STATRG ~IT1: =1 158 ;
159 9* GOTO DISPLY
160 ;
161 ;
~62 ;
163 DEK01:
164 ;* '~EST IF DIVER HAS ASCENDED TO 0.5M ?9 NO

TabIe 18 165 ;* ~~ GOTO DEK02 ~r 167 ; -~ TEST DEPTH = 0~5~ ?
DECO 168 ;* YES-~ TEST AT DECOEND ?, YES-~ GOTO DEK05 *
Page 4 170 ~-~TEST STATRG BIT5 = 1 171 ;* NO-~ DIVER HAS ASCENDED WITHO~ DECOI~RESSING *
172 ;* AS PRESCRIBED *
173 ;
174 ;* SErr OUT OF RANGE ~~ PORT2 ~IT7. =1 *
175 ;
176 ;* GOTO DISPLY *
177 ;
178 ;
179 ;
180 DEK02:
181 ;* TEST AT DECODEND?~ NO-~ GOTO DEK03 *
182 ; S TEST STATRG ~IT5 =1 ?
183 ;
184 ;* YES-~ M VER ~AS COMPLETED DECO~IPRESSION *
185 ;* AS PRESCRIBED *
186 ;
187 ;~ WAIT LOOP 30 SEC~ FOR RETURN *
188 ;* TO THE SURFACE REGION *
189 ; -~DO'~C30: = DOW~30-1 190 ;
191 ;
192 ;* TES~ WAI~ 30SEC~ ?, NO GOTO DISPLY *
193 ; ~~ DOWC30 = O ?
194 ;
195 ;* YES-~ SET FOR A NEW DIVE *
196 ~
197 ;* NOT DECOEND ~ STATRG BIT5 = O *
198 ;
199 ;* SET TIMERS *
200 ;
201 ;* ~OTTOMTIME: = 30SEC~ *
202 ~* DIVETIME:= O IN SECONDS AND MINUTES *
203 ;
204 ;* GOTO DEKo6 *
205 ;
206 ;
207 ;
208 DEK03:
209 ;* TEST IS D3COTIME OF PRESENT DECO-DEPTH~STAGE
210 ;* ELAPSED~ I~E~ : ZERO ?, NO-~ GOTO DISPLY
211 ; -~ TEST DEKOT ~ O ?
212 ;
213 ;* YES-~ DETE~INE NEXT HIGHER DECO-DEPTH-STAGE
214 ~ -~D~DEK: = DEDEK-3M XXXXXX FOR TA~. 0~700 ONLY
215 ;
216 ;
217 ;* TEST DECO~PRESSION CO~LETED ?, N5-~ GOTO DEK04 *
218 ; -~ D~DEK ~ O ?
219 ;

- 117 ~ 05 3 Table 18 220 ;* YES~ DIVE PROPERLY COi~PI,ETED WITH *
Program 221 ,* DECO~PÆ SSION *
DECO 223 ;* DETER~INE REP. GROUP WITH TXE BOTTO~ITIME AND THE *
Pa~ 5 224 ;* rlLX. DEPTH IN 'l'~E REPETI'rIVE TABLE *
225 ; -~ PREPARE AND CALL SUBR. BRPDEC
226 ;
227 ;* SET AT DECOE~iD -~ STATRG ~IT5: =1 *
228 ;
229 ;* SET (DECOTIME TOTAL): = O, ~ MI~TES AND SECONDS
230 ; -~ DEKOTT: = O
231 , 232 ;* GOTO DISPL~
233 ;
234 ;
235 ;
236 DEK04:
237 ;* DE~ER~INE DECOTIME WI'~H THE DECO-DEPT~-STAGE~ *
238 ;* THE DOTTOMTIME AND 'rHE MAX. DIVE DEP'nH~ IN THE *
239 ;* DECOMPRESSION TABLE. *
240 ; -S P Æ PARE AND CALL S~BR. ~DEKOT
241 ;
242 ;* GOTO DISPLY *
243 ;
24~ ;
245 ;
246 DEX05:
247 ;~ M VER HAS RET~RNED TO THE SURFACE REGION
24~ ;* WI'rHIN 30 SEC.
249 ;* SET S'rATES, F~AGS AND TIMERS
250 ;
251 ;* NOT DECOi~PRESSING -~ PORT2 ~I'r5: =0 *
252 ;* AT SUR~ACE ~ S'rATRG ~ITO: =1 *
253 ;* NOT DECOEND -~ STATRG LIT5: =0 * - - -254 ;~ AT SURFACEIN~ERVAL-~ S'rATRG ~IT3: =1 *
255 , 256 ;* SET DEPTH-S'rAGE = 6M~ FOR REPETITIVE DIVE
257 ; -~ DEST: ~12 258 ;
259 ;* DIVETIME: =O ~ IN MINUTES AND SECONDS
260 ;
261 ;* GO'rO DISP~Y *
262 ;
263 , 264 ;
265 E~D
USER S~IBO~S

ASSE~LY C0~1PLETE. NO ERRORS

- 118 ~ L8~6:) ~3 Table 20 1 ; *Y~X~-X~y~y~x~x~ X~Y~-X-)~X-3~:i X )~ X-X~X-X-Y~ ~X-Y~Y. X `: X~X-Pr am. 2 ;*
ogr . 3 ;* DISPLY
DISPLY 4 ;*
5 ; - ~ c --Page 1 6 ;*
7 ;*
8 ;* MAIN PROGRAM TO PREPARE AND OUTP~r r~E DISPLAY
9 ;* VhLUES FOR THE LCD DISPLAY.
10 ;*
11 ;* ~HE PROGRAM GENERATES T~REE M FFERENT DISPLA~
12 ;* i~;ODES~
13 ;*
14 ;* 1~ DECO~CO~PUTE C~IPO: = DIVE T~tE, ~-DN.
15 ;* C~Pl: = ACTUAL DIVE DE?I~ M
16 ;* CHIP2: = ASCENT T~E~ ~N
17 ;* - CEIP3: = DECO-STAGE T~E, MI~
18 ;* DECO--SrrAGE DEPrrH~ M
19 ;*
20 ;* 2. SOFTWAREERRROR. CHIPO: DIGITO: = E~A1L
21 ;* O'l'HEX DIGITS OF THE CO~PLETE
22 ;* DISPLAY ~~ LLANKS
23 ;*
24 ;* 3~ o~rr OF RANGE~ C~IPO: = DIVE TI~iE~ MIN.
25 9* CEIP1: = ACTUAL DEPT~? M
26 ;* CEIP2: = BLANKS
27 ;* CHIP3: = DECO-STAGE T~ ~ BLAN~
28 ;* DECO-ST~GE DEP~E ~~
29 ;* -~ k ~ , DIYE DEPTH
3o ;*
31 ;* 4~ POWER DOWN~ ONE OF TEE ABOVE DISPLAY MODES
32 ;* ~T FLASHING AT 005 SEC.
33 ;* INTER~ALS WITE BLANKS OVER - - -34 ~* ~ THE W~OLE DISPLAY~
35 ;*
36 ~*
37 ;* NOTE: T~E LCD DISPLAY IS SERVED FROM PORT P1 OF
38 ;* THE ~fC-48~ ~EE MOSq~SIGNIFICANT 4 ~ITS CONTAIN THE
3~ 9* FIG~RE TO ~E O~PUT~ IN LCD CODE~ T~E LEAS~
40 ;* SIGNIFICANT 4 PITS CONTAIN T~E CODE-WORD FOR
41 ;* ADDRESSI~G TEE DIGITS TO PE DISPLAYED ON THE
42 ;* DESIRED C~IP~ 'T~E CODE-WORD ADDRESSES 4 DIGITS PER
43 ;* CEIP AND 4 CHIPS ON THE DISPLA~.
44 ;*
45 ;~ CYCLIC STARTING OF THIS PROGRAM EVERY 0.5 SEC.
46 y*
~7 ;*
48 ; .
49 ;*
50 ,*
51 ;*
52 ;*
53 S*****~ u~
54 ;

A- 119 ~ s~

rrable 20 55;
Progxam: 557 ~-x~)~ x Q x)~ (x)~xx-x-~x DISPLY 58;
59;
Page 2 60; DEPr~: EQU 58 61 ~ DEMAXD EQU 56 62; DEDl~ EQIJ 53 63; DEKOrr EQIJ ~35 64; UPDIVrr EQU ~i4 65 ; D [YErr EQIJ 33 66; DISP16 EQU 29 ;DISPI~AY VALIJE~ UPPER 8 BIrrS
67; DISP8 EQU 2B ;DISPLAY VALUE~ LOWER 8 :BIrrS
68; DOWNC1 EQ~ 27 69 ; DISPCO EQIJ 25 ; DISPLAY--COI~NI~
70; SrrATRG EQI~ 24 71;
72;
73;
74;
75; S'rArrEMENrrS
76 ;**~**~ x)~x~H~X*
77;
78;
79;
80 DISPLY:
81;
82;
83;
84 DISO:
85 ;* PREPAPE DISPLAY VALIJl~S *
86 ;* FOR DECO-CO~Jql~ MODE *
87;
88 ;* r~ESr~ DISPCO = O ?, NO-'~ GOrrO DIS1 89;
90 ;* YES- ' DIS8: = DlVk;rr *
91;
92 ; * GOrrO DIS5 *
~33;
94;
95;
516 DIS1:
97 ;* rrES'r DISPCO = 4 ?. NO--~ GOTO DIS2 98;
99 ;* YES--~ CONVERrr DEE"r~IIN ~ESJ r~o ACCm~ACY OF *
100 ;* HI~LF A MErrRE AND SE'r AS DISPLAY VALIJE. *
101 9* CONVERSION rro 16-BIrr VALUE *
102;
103; -~ (DEPr~)~2 9 D~?rr~I IN MEq~RES
104; ~~ r~ESrr CARRY ~ 9 ?. X-ES--3 GOTO NXDIS1 105; ~>` NO~ ADD I~IE HALF'--ME~E~E Sr~EP=5 rro r~E DEPr 106 9 --~ 16 :13Ir~ ADDIrrION
107;
108;
109 ;* GOTO DIS5 *

- 120 - ~ ~ ~3 Table 20 110 ;

Program: 112 ' DISP~Y 113 NXDIS1:
Page 3, ll5, -~ YES, ADD HALF-METRE S'rEP = O TO DEP'rH
116 ;* GOTO DIS3 *
117 ;
118 ;
119;
120 DIS2:
121 ;* TEST DISPCO = 8 ?~ NO-~ Gorro DIS3 *
122;
123 ;* YES-~ DISP8: = I~'DIVT *
124 ;
125 ;* GO'rO DIS3 *
126 ;
127 ;
128 ;
129 DIS3:
130 ;* 'rEST M SPCO = 12 ?p NO-~ GOTO DIS4 *
131 ;
132 ;* YES
133 ;* (DEPT~+1)/2 - ~' CONVERT DECO STAGE DE~TH INTO ME'rRES
134 ;
135 ;* GOTO DIS5 136 ;
137 ;
138 ;
139 DIS4:
140 p* DECO-STAGE TIME - ~ DISPLAY VALUE *
141 ;
142 ;
143 ;
144 DIS5.
145 ;* ~EST AT POWER DOWN ?p NO-~ GOTO DIS6 *
146 ; -~ INP~T PIN Tl = O ?
147 ;
148 ;~ YES-~ POWER DO~N MODE
149 , 150 ;
151 ;* TEST DOWNCO~NTER-1SEC = O ?, NO-j GOTO DIS6 *
152 ;
153 ;* YES-~ DISP8: = Op DISP16: = O *
154 ;
155 ;
1~6 ;
157 DIS6:
158 ;* ~INARY~CD CONVERSION QF DISPLAY VALUE WI'~
15g t* DETECIION AND ~LANK CODING OF LEADING ZEROS. '~EST FOR
160 9* SOFYWARE-ERROR. IF YES/ ENCODE CORRESPONDING VAL~ES~
162 ,* TES~r (DISP8 AND DISP16 ) = O ?, YES-S GOTO DIS7 164 ;* NO-~ TEST FOR SOFYWARE-ERROR ?p YES-~ GOTO DIS7 - 121 ~ 3 TabIe 20 165 , -~ STATRG BIT6=1 ?
P g 167 g* NO-~ PRE~'ARE AND CALL SUBR. 3IN3DC *
DISPLY 168 ;
Page 4 169 ,* GOTO DIS8 *
171 ;
172 ;
173 DIS9:
174 ;* PREPARE DISPLAY VALUES FOR THE SOFTWARE ERROR
175 ;
176 ;* GOTO DIS8 *
177 ;
178 ;
179 ;
180 DIS7:
181 ;* ALL DISPLAY VALUES ARE ZERO - SET ALL FOR ~LANKS
182 ;
183 ;
184 ;
185 DIS8:
186 ,* TRANSr~T ALL DISPLAY VALUES, FIGURE 3 TO FIGURE 0, 187 ;* IN REGISTER R4 AND R5 SERIALLY TO THE DISPLAY~
188 ;* ~EGIN~ING WITH DIGI~ O TO DIGIT 3 ON CHIP 3 189 ;* R5 WILL BE TRANSMITl~D ~WI~E. WITH 2 FIGURES EAC~
190 ;~ TI~E.
191 ;* ALSO, FOR EACH FIGURE TRANSMITIæD, IHE DISPLAY
192 ;* CO~lrER ~DISPCO) WILL BE INCRh~ENTED BY ONE.
193 ;
194 ;* TEST DISPCO ~ = 12 ?~ YES-~ GOTO DIS10 *
195 ;' 196 ;* NO-~ TRANSMIT 4 FIGURES TO IHE DISPIAY
97 ;
198 ;
199 ;
200 DIS10:
201 ;* YES- ~ ~ANSMIT 2 FIGURES TO ~HE DISPIAY
202 ;
203 , 204 ;* RESET THE DISPLAY VALUES *
205 ;* -~ DISP8: = O. DISP16: = O *
206 ;
207 ;
208 ;* TEST DISPCO = 16 ?, YES-~ GOTO DIS11 *
209 ;
210 ;* NO-~ TEST FOR SOFTWARE-ERROR ?, NO- ~ GOTO DISO
211 ; ~STA~RG PI~6=0 ?
212 ;
2~3 ;
214 ;
215 DISll~
216 ;* YES-~ REINITIALISE DISPLAY COI~ R *
217 ; ~ DISPCO: = O
218 ;

li~$¢~S3 T~ble 20 220 ;* WAIT-LOOP TO DETECT WHETHER THE PROGRAM
221 ;* IS STARl'ED CYCLICALLY EVERY 0.5 SECONDS
222 ;* ~Y 'l'~E HTI~o DISPLY 223 ;* THE WAIT-LOOP LASTS APPROX. 1.5 SECONDS.
p 5 224 ;* IF IT IS NOT INTERR~PTED DURING THIS
225 ;* T~qE, THE SO~T~ARE-ERROR STARTS
226 ;* -~ SET STATRG ~IT6: = 1 227 ;* - Y GOTO CHKSET
228 ;
229 ;
230 ;* WAIT~LOOP *
231 ~
232 ;
233 ;* SET AT SO~T~ARE ERROR *
234 ;
235 ;
236 ;* GOTO CHKSET *
237 ;
238 ;
239 ;

~SER SY~OLS

ASSEMBL~ CO~PLETE. NO ERRORS.

- 123 ~ 605 ~able 21 ---- Addr. Program Program:
~E~Io~y p _ O ' ~IP ~ES~AR~ Reset vector Page ~ E
A . 2 . . ~_ External interrupt T ,~ _ ~r _ vector G JMP ~T~E Timer interrupt ~ ~ector-S HT~E: Generates the 0.5 s timing Y pulse from the timer S interrupt9 Test: Timer=0~5s?
~ Yes: ~IP PSNORC
E NO: ~P Return M RS~ART: Initialisation and start of _ interrupt-timer~ JMP PSNORC
M PSNORC. Acquisition of pressure A , _ I CHKSET: Check-and-set routine for N all timers~ counters and variables~ ~IPs to sundry P . main programs R SURFAC: Surface region G ~IP DISPLY
R DIVE. Diving A JMP DISPLY
M 3lVh;U~: As~ent .
J~ DISPLY
DECO: Decompression JMP DISPLY
DISPLY: I Output to displa~9 incl 1.5 s wait-loop 2 k Limit - _ _ . _ _ _ _ S ~ LIB- All sub-routines needed U O
U _ T
I

N
E
S

~ 124 -rable 22 1 ;-~Y~ ~xx~***-x~**~xx-x-x-x-~x~**~x--xxy~x-~xx~y~*~
2 ;*
Prog~am: 3 ;* VARLS~
VARLS'r`~ 4 ;*
Page 1 5 '* - ~-7 ;* I~HIS PROGRAM CON~rAINS ALL NON-LOCAL VARIABLES
8 ;* USED IN THE SOFTWARE OF THE DEcoc~ipu~rER~ WI~rH
9 ;* TEEIR EQUArrES.
10 ;*
11 ;* IN ADDIrrIoN9 A LIsrr OF rrHE suB-RourINEs USED IS
12 ;* ATrrAc~ED.
13 ;*
14 ;*
16 ;*
17 ;*
18 9*
19 ;*
20 ;xxxxvxxxxxx-xx-xxxxxx-x-*x--xxxxxxxxxxx~*****~--~*-xxxxx-~xi~x-x-21 ;
22 ;
23 ; EQ~ArrEs 24 ;~xxxxxxx-xxy~x~txxxx~;xxx 25 ;
26 ;
27 ; VARIABLES

003F 29 PAL'r EQ~ 63 ; OLD PRESS~RE
003E 30 PNEU EQU 62 ; NEW PRESSURE
003D 31 PN~LL EQ~ 61 ; A~IOSPHERIC PÆ SSURE
003C 32 PALT30 EQ~ 60 ; PRESS~RE 30 SECONDS AGO
003L 33 DELrrAp EQU 59 ; P Æ SSURE DIFFERENCE
oo3~ 34 DEPT~- EQ~ 58 ; AC~UAL DIVE DEPT~
oo39 35 DEMAXV EQU 57 ; MAXo DIVE DEP'rH (VARIABLE) oo38 36 DE~ D EQU 56 ; ~LX. DIVE DEPTg (DISPLAY) oo37 37 DEST EQU 55 ; ACT~AL DEp~n~-srrAGE
oo36 38 DES'~g -- EQU--54 - - --- -;--coRREcTIoN-DEprrH-srrAGE
oo35 39 DEDEK EQ~ 53 ; AC~UAL DECO DEPTH STAGE
oo34 40 DEDEKM EQU 52 ; ~AX. DECO DEP~H S~rAGE
oo33 41 AASL EQU 51 ; ALTI'~UDE ABOVE SEA LEVEL
0032 42 RPGRUP EQU 50 ; AC~UAI, REP. GROUP
oo31 43 RPGEND EQU 49 ; REP. GROUP AT END OF THE
44 ; SURFA Æ INTERVAL
0030 45 RPGZZU EQU 48 ; REPETI'rIVE ADDED-TIME
002F 46 BOTSEC EQ~ 47 ; BOTT~ll'~E(SECONDS PART) G02E 47 BOT EQU 46 ; BOr~rO~lT~5E~NUTES PART~
002D 48 ~OTK ÆQU 45 ; CORRECTION BOr~rOMT~Æ
002C 49 T3T EQU 44 ; TE~;PORARY BOTTOMT~E
002B 50 BOTZZ EQU 43 ; ~OITOMT~E ADDED-T~E
51 ; (MIN~TES PART) 002A 52 BOTZZS EQ~ 42 ~ ; BOTTOMTI~5E ADDED-TI~E
53 ; SECO~DS PART
0029 54 sFINrrT EQU 41 ; SU~FACÆ IN'l'~RVAL T~Æ

5~
~ 125 -Table 22 55 ; (iiIN~TES PART) Program. 56 S~ISEC EQ~ 40 ; SURFhCE INr~F.RVhL TI~E
57 0028 ; ~SECONDS PMT) VARLST 58 KEGÆLT EQU 39 ; ASCENT CONE TI~iE MIN~TES PART) P 2 59 KEGSEC EQ~ 38 0027 ; ASCEIIT CONE TI~iE SECONDS PART) age 60 DÆKOTrr EQ~ 37 0026 ; DECO-T~E ~ TOTA
61 DhKOTS EQU 36 0025 ; DECOT~E (SECONDS PhRT) 62 DEKOT EQ~ 35 0024 ; DECOT~IE
63 UPDIVT EQ~ 34 0023 ; UPDIVETIME (ASCE~T T~IE) 64 DIVET EQU 33 0022 ; DIVET~IE ~i~U~JrES PART
65 DIVETS EQU 32 0021 ; DlV~T~E SECONDS PMT
66 SDE~OT EQ~ 31 0020 ; S~M OF DE O - T~ES
67 ; SP~RE EQU 30 001F
68 DISP16 EQU 29 ; UPPER 8 ~ITS OF DISPLAY VhLUE
69 DISP8 EQ~ 28 001D ; LOWER 8 BITS OF DISPLhY VALUE
70 DOWNC1 EQU 27 001C ; DOWNCO~rrER FOR 1 SEC
71 DOWC30 EQU 26 001B ; DOWNCO~IrER FOR 30SEC~
72 DISPCO EQ~ 25 001A ; DISPLAY CO~'l'~R
73 STATRG EQU 24 0019 ; STArr~S REGISTER
74 ; 0018 75 ;
76 ;
77 ; SUBROUTINES:
78 ;
79 ;
80 ; SUB ; SUB~RACTION~ DIRECT
81 ; SUBD ; SUBTRACTION, INDIRECT
82 ; ~P8X8D ; ~LTIPLICATIONJ DIRECT~ 8X8 3ITS
83 ; DIV8D ; DlVlSION~ DI~ECT, 8/8 ~ITS ~~ 8 BI~S
84 ; BINBCD ; BINARY-PCD CONVERSION WIT~ SUPPRESSION
85 3 ; OF LEADING ZEROS
86 ; BRPGSF ; DETER~INATION OF THE REPo GROUP WIT~
87 ; ; SURF~CE INTERVAL TA~TJE
88 ; BRPGUW ; DETERMINATION OF THE REP. GRO~P WITH
89 ; ; T~E REPETITIVE TABLE
90 ; BRPDEC ; DErrERMINATION 0~ T~IE REP~ GROUP WIrrH
91 ; ; THE DECOMPRESSION TABLE
92; BZZU, ; DETER~ ATION OF 'l'~ ADDED Tl:r3 WITH
93 ; ; THE REPETITl V~! TABLE
94; BDEST ; DETEF~INATION OF 'l'llE ACTIJAL
95; ; DEPTH STAGE AS PER DECQ
96; ; TABLE
97; BDESTN ; DErl~1INATION OF THE NEXT DEPTH
98 ~ ; STAGE AS PER REP O TABLE
99; BZT ; DErE~iINATION OF 'l'~E ZERO--TII~E
100; BDEKOT ; DETERMINATION OF TE~E DECO-TIME AT
101 ; ; A GIVEN DECO DEPTE STAGE
102 ; BDECOW ; DErrERMINArrION OF THE FOLLOWINGr YALUES:
103 ; ; ~ SUM OF THE DECO TIMES
104; ; ~ MAX~ DECO. DEPTH STAGE
105; ; ~ TIME ArI~ ~rHE r~x. DECO~
106 ; ; - DEPTE STAOE
107 ; FNEXTT ; POSITIONING OF THE POINrl~EI
108 ~ ; AT THE START OF THE NEXr 109 ; ; ~ABLE

~ 126 ~ ~ L8~)S3 TabIe ?2 :110 ; XREPTB ; AUXILIARY ROUTINE FOR ALL
111 ; ; SUB-ROUTINES, W~ICH USE
P gr 112 ; , TRE REPETITIVE TABL¢
VLRLST 113 ; XDECTB ; A~XILI~RY ROUTIN¢ FOR A~L
114 ; ; SI~B-ROUTINES, 'Y1XICH IJSE
pa~e 3 115 ; ; THE DECOMPRESSION TAE3 116;
117;
118 ; END
USER S~OLS
AASL 033 ~OT 002E BOTK 002D BOTSEC 002F BOTZZ 002B BOTZZ
DEKOT 0023 DEKOTS 0024 DEKOTT 0025 DELTAP 003~ DE~XD 0038 DE~
DESTK oo36 DISP16 001D DISP8 001C DISPCO 0019 DIV¢T 0021 DIVET
KEGELT 0027 l;~EGSEC 0024 PALT 003F PALT30 003C P ~ 003E PNIJLL
RPGZZU 0030 SDEKOT OOlF SFINTT 0029 SFISEC 0028 STATRG 0018 T~T
ASSE~LY COI~LETE. NO ERRORS

Claims (16)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. Indicating device for the parameters of a diving operation such as, for example, present depth, maximum depth reached, previous elapsed diving time or the like, which indicating device is driven through (a) at least one memory for the decompression para-meters at a series of diving depths and times and (b) an evaluation and logic stage for the measured values of the depth gauge and timer, with the values stored in the memory, characterized by the fact that, at any time during the dive, the necessary total resurfacing time, depending on the depths and times of diving, including the specified decompression stops, can be indicated,and/or a converter device is provided for conversion of the present bottom time, on entering a new diving depth stage, into the equivalent bottom-time for this new diving depth stage.

2. A device in accordance with Claim 1, wherein with the aid of the converter device, the air pressure, preferably measured in each case with the aid of a measuring instrument, is also taken into account.

3. A device in accordance with Claim 2, wherein a single pressure gauge, preferably including a piezoresistive measuring cell, both for the air pressure and water pressure, is connected to the circuit containing the converter device.

4. A device in accordance with Claim 3, wherein the measuring range of the pressure gauge is switchable for measurement of air or water pressure with the aid of a switching device.

5. A device in accordance with Claim 1, wherein a differentiating stage is connected to the output of the pressure gauge.

6. A device in accordance with Claim 4 wherein the switching device comprises a step detection stage for the pressure, formed for example by the differentiating stage.

7. A device in accordance with Claim 4, wherein -for example for an evaluation and logic stage of limited working range - a range change can be carried out with the aid of the switching device, by switching the gain or the bit-range of an analog-digital converterconnected before the evaluation and logic stage.

8. A device in accordance with Claim 7, wherein a reference voltage source, switchable by the switching device, is provided and is conveniently followed by an analog-digital converter.

9. A device in accordance with Claim 4, wherein the switching device includes at least one FET switch.

10. A device in accordance with Claim 9, wherein an impedance converter is connected after the FET switch for decoupling with respect to the input of the following stage, especially the analog-digital converter.

11. A device in accordance with any one of the Claims 1 to 3, wherein in case of occurrence of an abnormal function, a warning signal and/or a slave indicator for the maximum diving depth reached can be switched on by a detector circuit consisting of a timer and a pressure sensor.

12. A device in accordance with Claim 1, wherein the converter device comprises a computer and memories for bottom-times and/or decompression times and/or repetitive groups.

13. A device in accordance with Claim 12, wherein the memory is or the memories are of the tabular memory type.

14. A device in accordance with any one of the Claims 1 to 3, wherein the converter device includes a memory circuit for the depths and times of diving in each case, as well as the correction values obtained where applicable.

15. A device in accordance with any one of Claims 1 to 3, with at least one segment display, wherein the segment display can be switched alternately - e.g. before and after occurrence of an abnormal function - to display different data.

16. A device in accordance with any one of Claims 1 to 3, wherein an astable multivibrator circuit is provided for the cyclic activation of at least one display.