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Network Working Group                                          J. WinettRequest for Comments: 109                         MIT Lincoln LaboratoryNIC: 5805                                                  24 March 1971Level III Server Protocol for the Lincoln Laboratory360/67 HostDisclaimer   This material has not been reviewed for public release and is   intended only for use with the ARPA network.  It should not be quoted   or cited in any publication not related to the ARPA network.Introduction   The Lincoln Laboratory IBM 360/67 is connected to the ARPA network   and acts as a serving host providing access to the CP-67 virtual   machine operating system.  Upon completion of the Login procedure,   users have control of a 360 virtual machine through a virtual 1052   online console.  Attached to the virtual machine is a virtual card   reader, card punch and line printer, and a number of disk storage   devices.  The 360 virtual machine can be either a virtual 360/67 with   dynamic address translation hardware or a standard System/360.  Most   users run a standard 360 with 256K bytes of virtual memory and   operate the CMS conversational monitor system.  CMS provides   facilities for file creation, maintenance and manipulation, program   development, debugging and execution, and a number of other useful   utility functions.  The section in the Network Notebook on the   Lincoln Laboratory 360/67 more fully describes the facilities   available.Network Control Program   All communication with the 360/67 through the IMP are processed by a   Network Control Program (NCP).  The NCP operates with the Host-Host   Protocol described in the Network Working Group Document No. 1 dated   3 August 1970.Initial Connection Protocol   To create a virtual machine from the network, a pair of connections   must be made with the LOGGER.  The sockets to be used are assigned   following the Initial Connection Protocol (ICP).  The LOGGER is   enabled and waiting for an RTS control command for socket X'0A 0000   01'.  This ICP socket corresponds to home X'0A', user X'0000', and   tag X'01' (send gender).  Requests for connection on the ICP socket   are stacked until it becomes free.  If the LOGGER is willing toWinett                                                          [Page 1]

RFC 109                 Level II Server Protocol           24 March 1971   service another network user, a 32 bit socket ID of a receive socket   will be sent over this initial connection and the ICP socket will   then be closed.  If the LOGGER is not willing to service another   network user, it will not complete the initial connection for the ICP   socket and will refuse the request by closing the connection without   completing it.LOGGER Protocol   Once a pair of user sockets have been assigned, the connection   protocol should be completed on these sockets.  The LOGGER then   expects to receive (on the receive socket) one 8-bit byte indicating   the data type which characterizes the transmission code used to   communicate with the network user over this pair of sockets.  A code   of X'01' implies 7 bit ASCII code in 8-bit bytes with the leading bit   zero.  A code of X'02' implies 8-bit EBCDIC code.  When the data type   code is received, the LOGGER will echo back the data type code over   the send socket followed by the message:            LINCOLN LABORATORY CP-67 ONLINE NL   in the appropriate code.  (In ASCII, NL is transmitted as CR LF).   The procedure continues according to the normal CP-67 login protocol   with the LOGGER performing an additional function of mapping network   userids and passwords into valid CP-67 userids and passwords.  This   mapping is specified by entries in a file (the LOGGER FILE) which the   LOGGER accesses.  If a network userid does not match an entry in the   file or if the password given does not match the corresponding   network password, the usual CP responses will be sent to the users.   Thus network access to the Lincoln Laboratory system is restricted to   those accounts for which an appropriate entry has been made in the   LOGGER FILE.   It should be noted that CP transmits a BYP code (Bypass) to suspend   the printing of characters keyed while a password is being entered.   After the password has been entered, CP transmits a RES code   (Restore) to resume the printing when characters are keyed.  When   communicating in ASCII, these character codes are converted to X'FF'   since no corresponding ASCII code is defined.  Refer to the Network   Resource Notebook for more details on CP-67 and on CMS.The NET Account   Lincoln Laboratory is providing one account which can be used by   network users to familiarize themselves with our time-sharing system.   The userid of this account is NET and the password is ARPA.  This   account has 900 records of storage, which can store approximatelyWinett                                                          [Page 2]

RFC 109                 Level II Server Protocol           24 March 1971   720,000 characters.  NET users are free to ERASE any file on this   account since many different people may use this account.The SERVER Protocol   CP-67 operates on a line at a time, i.e., a group of characters are   processed as a line and not as a sequence of individual characters.   Also, the system does normally buffer input lines, that is, input is   not normally entered until requested by a read from the system.  With   IBM 2741 or 1052 terminals, the keyboard is locked until a read is   requested.  The virtual terminals through which network users have   access to the CP-67 system have been designed to support either a   line oriented terminal or a character oriented terminal.  When CP   requests a line of input, the SERVER transmits a prompting code   X'80'.  This character can be used to signal a user process to change   transmission modes and to transmit an input line.  Characters   received by the SERVER are buffered until a NL character is received.   Lines received can then be used to satisfy CP requests for an input   line.   CP may send out lines which may or may not end with a NL character.   If a line does not end with a NL character, the prompting character   will naturally be sent following the output line to request input to   a CP process.   When a user wishes to interrupt a CP process, i.e., to change modes,   an interrupt code X'80' should be sent to the SERVER.  This code will   result in an asynchronous interrupt being sent to the running   process, stimulating the pressing of the 'attention' button on a 2741   terminal.  Together with the transmission of the interrupt code, the   user should cause an INS to be sent over the send link.  This signal   will be synchronized with the interrupt code.  If the interrupt code   has not yet been received and processed, all characters buffered and   those received before the receipt of the interrupt code will be   flushed, i.e., deleted.  When the interrupt code is received, it will   be paired with the previously received INS.  If an INS is received   after an interrupt code has been received and processed, the INS will   be paired with this previously received interrupt code.   If CP has a line to send to a user after it has requested an input   line but before it has received any input, the SERVER will transmit   an INS on the user's receive link to notify the user that previously   sent prompting character should be retracted and that a line has been   or will be sent to the user.  This message line is called a   "warning".Winett                                                          [Page 3]

RFC 109                 Level II Server Protocol           24 March 1971Graphic and Control Codes   Figure 1 gives the 8-bit codes for the EBCDIC graphics and controls.   Figure 2 gives the 7-bit codes for the ASCII graphics and controls.   The controls are tabulated and compared in Figure 3.  The standard   interpretation of the ASCII controls are given in Figure 4.   There are 4 ASCII codes which do not have a corresponding graphic or   control in the EBCDIC code.  The EBCDIC codes given to these codes   are as follows:                   |     Hex Code             ASCII |-------+--------            Symbol | ASCII | EBCDIC            -------+-------+--------               DC3 |  13   |  3A                   |       |                `  |  60   |  70                   |       |                \  |  5C   |  71                   |       |                ^  |  5E   |  72   There are 29 EBCDIC graphics codes and 19 EBCDIC control codes which   do not have a corresponding graphic or control in the ASCII code.  In   addition, there are 84 other EBCDIC codes whose interpretation is   unspecified.  Four of these codes have been chosen to correspond to   the ASCII control and ASCII graphics which do not have a   corresponding EBCDIC code.  When converting EBCDIC codes to ASCII   codes, the remaining 80 codes plus the 29 EBCDIC graphics and 18   EBCDIC controls (not counting NL) are converted into the code X'FF'.   The NL character is treated specially.  The NL character, EBCDIC code   X'15', is converted into the two character sequence CR LF, i.e.,   ASCII X'0D 0A'.  As stated above, the code X'80' is transmitted as a   prompting character whenever CP requests an input line.   On converting from ASCII to EBCDIC, if any code other than the 128   ASCII codes, or the interrupt codem X'80', is received, it is   converted to the code X'FF'.  In addition , whenever the two ASCII   characters CR LF are found sequentially in the input stream, they are   converted into the single EBCDIC character NL.   [In Figure 1, positions shown as "[?]" cannot be printed in ASCII.]Winett                                                          [Page 4]

RFC 109                 Level II Server Protocol           24 March 1971        0 0  0   0   0   0   0   0   0   1   1   1   1   1   1   1   1        1 0  0   0   0   1   1   1   1   0   0   0   0   1   1   1   1        2 0  0   1   1   0   0   1   1   0   0   1   1   0   0   1   1        3 0  1   0   1   0   1   0   1   0   1   0   1   0   1   0   1   4567+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+   0000|NUL|DLE|DS |   |SP | & | - |   |   |   |[?]|[?]|   |   |   | 0 |       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+   0001|SOH|DC1|SOS|   |   |   | / |   | a | j |[?]|[?]| A | J |   | 1 |       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+   0010|STX|DC2|FS |SYN|   |   |   |   | b | k | s |[?]| B | K | S | 2 |       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+   0011|ETX|TM |   |   |   |   |   |   | c | l | t |[?]| C | L | T | 3 |       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+   0100|PF |RES|BYP|PN |   |   |   |   | d | m | u |[?]| D | M | U | 4 |       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+   0101|HT |NL |LF |RS |   |   |   |   | e | n | v |[?]| E | N | V | 5 |       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+   0110|LC |BS |ETB|UC |   |   |   |   | f | o | w |[?]| F | O | W | 6 |       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+   0111|DEL|IL |ESC|EOT|   |   |   |   | g | p | x |[?]| G | P | X | 7 |       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+   1000|   |CAN|   |   |   |   |   |   | h | q | y |[?]| H | Q | Y | 8 |       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+   1001|   |EM |   |   |   |   |   |   | i | r | z |[?]| I | R | Z | 9 |       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+   1010|SMM|CC |SM |   |[1]| ! |   | : |   |   |   |   |   |   |   |   |       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+   1011|VT |CU1|CU2|CU3| . | $ | , | # | { | } |[?]|[?]|   |   |   |   |       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+   1100|FF |IFS|   |DC4| < | * | % | @ |[?]|[?]|[?]|[?]|   |   |   |   |       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+   1101|CR |IGS|ENQ|NAK| ( | ) | _ | ' |[?]|[?]| [ | ] |   |   |   |   |       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+   1110|SO |IRS|ACK|   | + | ; | > | = |[?]|[?]|[?]|[?]|   |   |   |   |       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+   1111|SI |IUS|BEL|SUB| | |[2]| ? | " |[?]|[?]|[?]|[?]|   |   |   |   |       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+                         +---+---+---+---+---+---+---+---+                         | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |                         +---+---+---+---+---+---+---+---+                                   Code Structure                                      Figure 1.            Extended Binary-Coded Decimal Interchange Code (EBCDIC)Winett                                                          [Page 5]

RFC 109                 Level II Server Protocol           24 March 1971            8 0   0   0   0   0   0   0   0            7 0   0   0   0   1   1   1   1            6 0   0   1   1   0   0   1   1            5 0   1   0   1   0   1   0   1        4321+---+---+---+---+---+---+---+---+        0000|NUL|DLE|SP | 0 | @ | P | ` | p |            +---+---+---+---+---+---+---+---+        0001|SOH|DC1| ! | 1 | A | Q | a | q |            +---+---+---+---+---+---+---+---+        0010|STX|DC2| " | 2 | B | R | b | r |            +---+---+---+---+---+---+---+---+        0011|ETX|DC3| # | 3 | C | S | c | s |            +---+---+---+---+---+---+---+---+        0100|EOT|DC4| $ | 4 | D | T | d | t |            +---+---+---+---+---+---+---+---+        0101|ENQ|NAK| % | 5 | E | U | e | u |            +---+---+---+---+---+---+---+---+        0110|ACK|SYN| & | 6 | F | V | f | v |            +---+---+---+---+---+---+---+---+        0111|BEL|ETB| ' | 7 | G | W | g | w |            +---+---+---+---+---+---+---+---+        1000|BS |CAN| ( | 8 | H | X | h | x |            +---+---+---+---+---+---+---+---+        1001|HT |EM | ) | 9 | I | Y | i | y |            +---+---+---+---+---+---+---+---+        1010|LF |SUB| * | : | J | Z | j | z |            +---+---+---+---+---+---+---+---+        1011|VT |ESC| + | ; | K | [ | k | { |            +---+---+---+---+---+---+---+---+        1100|FF |FS | , | < | L | \ | l | | |            +---+---+---+---+---+---+---+---+        1101|CR |GS | - | = | M | ] | m | } |            +---+---+---+---+---+---+---+---+        1110|SO |RS | . | > | N | ^ | n | ~ |            +---+---+---+---+---+---+---+---+        1111|SI |SU | / | ? | O | _ | o |DEL|            +---+---+---+---+---+---+---+---+    +---+---+---+---+---+---+---+---+---+---+---+---+            | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 |            +---+---+---+---+---+---+---+---+                     Code Structure                        Figure 2.   USA Standard Code for Information Interchange (USASCII)Winett                                                          [Page 6]

RFC 109                 Level II Server Protocol           24 March 1971   CAT     EBCDIC  ASCII   TTY     PTTC    FUNCTION           NUL     NUL     NULL            Null   CC      SOH     SOH     SOM             Start of Heading   CC      STX     STX     EOA     EOA (D) Start of Text   CC      ETX     ETX     EOM             End of Text   DC      PF                      PF      Punch Off   FE      HT      HT      H.TAB   TAB     Horizontal Tab   GR      LC                      LC      Lower Case           DEL     DEL     RUBOUT  DEL     Delete           SMM                             Start of Manual Message   FE      VT      VT      V.TAB           Vertical Tab   FE      FF      FF      FORM            Form Feed   FE      CR      CR      RETURN          Carriage Return   GR      SO      SO      SO              Shift Out   GR      SI      SI      SI              Shift In   CC      DLE     DLE     DC0             Data Link Escape   DC      DC1     DC1     X-ON            Device Control 1   DC      DC2     DC2     TAPE ON         Device Control 2           TM                              Tape Mark   DC      RES                     RES     Restore   FE      NL                      NL      New Line   FE      BS      BS              BS      Backspace           IL                      IL      Idle           CAN     CAN     FE0     CAN     Cancel           EM      EM      S1              End of Medium           CC                              Cursor Control   CU      CU1                             Customer Use 1   IS      IFS     FS      S4              Info. Field Separator   IS      IGS     GS      S5              Info. Group Separator   IS      IRS     RS      S6              Info. Record Separator   IS      IUS     US      S7              Info Unit Separator   ED      DS                              Digit Select   ED      SOS                             Start of Significance   ED      FS                              Field Separator   DC      BYP                     BYP     Bypass   FE      LF      LF      LF      LF      Line Feed   CC      ETB     ETB     LEM     EOB (B) End of Text Block           ESC     ESC     S3      PRE     Escape           SM                              Set Mode   CU      CU2                             Customer Use 2   CC      ENQ     ENQ     WRU             Enquiry   CC      ACK     ACK     RU      (Y)     Acknowledge           BEL     BEL     BELL            Bell   CC      SYN     SYN     SYNC            Synchronous Idle   DC      PN                      PN      Punch On   DC      RS                      RS      Reader Stop   GR      UC                      UC      Upper CaseWinett                                                          [Page 7]

RFC 109                 Level II Server Protocol           24 March 1971   CC      EOT     EOT     EOT     EOT (C) End of Transmission   CU      CU3                             Customer Use 3   DC      DC4     DC4     TAPE OFF        Device Control 4   CC      NAK     NAK     ERROR   (N)     Negative Acknowledge           SUB     SUB     S2              Substitute   DC              DC3     X-OFF           Device Control 3                       Figure 3                Control Functions Compared   CC   (Communication Control).  A functional character intended to         control or facilitate transmission of information over         communication networks.   FE   (Format Effector).  A functional character which controls the         layout or positioning of information in printing or display         devices.   IS   (Information Separator).  A character which is used to separate         and qualify information in a logical sense.  There is a group         of four such characters, which are to be used in a hierarchical         order.   DC   (Device Control).  A functional character used for the control         of ancillary devices associated with data processing of         telecommunication systems, more especially switching devices         "on" and "off".   ED   (Edit and Mark).  A control character used by the System/360         Edit and Mark (EDMK) instruction for the formatting of         alphanumeric fields.   GB   (Graphic Control).  A control character indicating that the code         combinations which follow are to be interpreted in a particular         code table, depending upon the particular control character.   CU   (Customer Use).  A character excluded from future assignment by         IBM.  These "protected" codes are intended for use by customer         systems so that their use will not conflict with a possible         future IBM use.                           Figure 3 (Continued)                     Categories of Control FunctionsWinett                                                          [Page 8]

RFC 109                 Level II Server Protocol           24 March 1971   NUL  (Null).  The all-zeros character which may serve to accomplish         time fill and media fill.   SOH  (Start of Heading).  A communication control character used at         the beginning of a sequence of characters which constitute a         machine-sensible address or routing information.  Such a         sequence is referred to as the _heading_.  An STX character has         the effect of terminating a heading.   STX  (Start of Text).  A communication control character which         precedes a sequence of characters that is to be treated as an         entity and transmitted through to the ultimate destination.         Such a sequence is referred to as _text_.  SIX may be used to         terminate a sequence of characters started by SOH.   ETX  (End of Text).  A communication control character used to         terminate a sequence of characters started with STX and         transmitted as an entity.   EOT  (End of Transmission).  A communication control character used         to indicate the conclusion of a transmission, which may have         contained one or more texts and any associated headings.   ENQ  (Enquiry).  A communication control character used in data         communication systems as a request for a response from a remote         station.  It may be used as a "Who Are You" (WRU) to obtain         identification, or may be used to obtain station status, or         both.   ACK  (Acknowledge).  A communication control character transmitted by         a receiver as an affirmative response to a sender.   BEL  (Bell).  A character for use when these is a need to call for         human attention.  It may control alarm or attention devices.   BS   (Backspace).  A format effector which controls the movement of         the printing position one printing space backward on the same         printing line (applicable also to display devices).   HT   (Horizontal Tabulation).  A format effector which controls the         movement of the printing position to the next in a series of         predetermined positions along the printing line (applicable         also to display devices and the skip function on punched         cards.)   LF   (Line Feed).  A format effector which controls the movement of         the printing position to the next printing line (also         applicable to display devices).Winett                                                          [Page 9]

RFC 109                 Level II Server Protocol           24 March 1971   VT   (Vertical Tabulation).  A format effector which controls the         movement of the printing position to the next in a series of         predetermined printing lines (also applicable to display         devices).   FF   (Form Feed).  A format effector which controls the movement of         the printing position to the first predetermined printing line         on the next form or page (also applicable to display devices).   CR   (Carriage Return).  A format effector which controls the         movement of the printing position to the first printing         position on the same printing line (also applicable to display         devices).   SO    (Shift Out).  A control character indicating that the code         combinations which follow shall be interpreted as outside of         the character set of the standard code table until a Shift In         Character is reached.   SI    (Shift In).  A control character indicating that the code         combinations which follow shall be interpreted according to the         standard code table.   DLE   (Data Link Escape).  A communication control character which         will change the meaning of a limited number of contiguously         following characters.  It is used exclusively to provide         supplementary controls in data communication networks.   DC1, DC2, DC3, DC4 (Device Controls).  Characters for the control of         ancillary devices associated with data processing or         telecommunication systems, more especially switching devices         "on" and "off".  (If a single "stop" control is required to         interrupt of turn off ancillary devices, DC4 is the preferred         assignment.)   NAK  (Negative Acknowledge).  A communication control character         transmitted by a receiver as a negative response to a sender.   SYN   (Synchronous Idle).  A communication control character used by         a synchronous transmission system in the absence of any other         character to provide a signal from which synchronism may be         achieved or retained.Winett                                                         [Page 10]

RFC 109                 Level II Server Protocol           24 March 1971   ETB  (End of Transmission Block).  A communication control character         used to indicate the end of a block of data for communication         purposes.  ETB is used for blocking data where the block         structure is not necessarily related to the processing format.   CAN  (Cancel).  A control character used to indicate that the data         with which it is sent is in error or is to be disregarded.   EM   (End of Medium).  A control character associated with the sent         data which may be used to identify the physical end of the         medium, or the end of the used, or wanted, portion of         information recorded on a medium.  (The position of this         character does not necessarily correspond to the physical end         of the medium.   SS   (Start of Special Sequence).  A control character used to         indicate the start of a variable length sequence of characters         which have special significance or which are to have special         handling.   ESC  (Escape).  A control character intended to provide code         extension (supplementary characters) in general information         interchange.  The Escape character itself is a prefix affecting         the interpretation of a limited number of contiguously         following characters.   FS   (File Separator), GS (Group Separator), RS (Record Separator)         and US (Unit Separator).  These information separators may be         used within data in optional fashion, except that the         hierarchical relationship shall be : FS is the must inclusive,         then GS, then RS, and US is least inclusive.  (The content and         length of a File, Group, Record, or Unit are not specified.)   DEL  (Delete).  This character is used primarily to "erase" or         "obliterate" erroneous or unwanted characters in perforated         tape.  (In the strict sense, DEL is not a control character.)                               Figure 4                        ASCII Control FunctionsWinett                                                         [Page 11]

RFC 109                 Level II Server Protocol           24 March 1971Endnotes   [1] - Cent sign   [2] - Logical not ("bent bar")   [?] - Graphics not in ASCII.  See Postscript or PDF version of         this document.          [This RFC was put into machine readable form for entry]          [into the online RFC archives by Lorrie Shiota, 10/02]Winett                                                         [Page 12]