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This is a custom bootstrap loader to load theAdaptable p-System IV for 8080/Z-80 on the Z80-MBC2 board.

The loader was initially designed to replace theautoboot.bin file on the SD card. It will mount oneor more UCSD Pascal disk images, then load and execute the secondary bootstrap from the first diskimage.

The bootloader can also be built as a bootloader for an additional disk set. In this case, the diskimage files will need to be renamed fromDS2Nxx.DSK toDSmNxx.DSK, withm = the disk set number. So,for the 4th disk set, the DSK names will begin fromDS3N20.DSK.

Two disk images have been prepared for this system. They have been converted from the original 77-track8 inch floppy disk images ; the link to the location from where the disk images is given below.

The new disk image format for the Z80-MBC2 board is of up to 77 tracks of 128 sectors, each of 128bytes, for a maximum of 1.2 megabytes. The images are stored in filesDSnNxx.DSK, withxx startingfrom20 for the first disk. The disk set 'n' must be chosen from the config screen, so for the disk setnumber2, we have to first activate CP/M 3.0 using the menu option8: Change Disk set ; then select4: Autoboot to load UCSD Pascal.

In the provided set:

• DS2N20.DSK = disk 0 =SYS1: (loaded as unit#4);
• DS2N21.DSK = disk 1 =SYS2: (loaded as unit#5);

1. Copy the providedautoboot.bin file and the 2 disk imagesDS2N20.DSK andDS2N21.DSK to the root folder of the SD card.

2. Start the Z80-MBC2 with the USER button pressed, to get the config menu.

3. Select Disk Set 2 (CP/M 3.0) using the menu item8: Change Disk Set.

4. Choose boot mode4: Autoboot.

5. Enjoy UCSD Pascal.

It is possible to configure some settings of the UCSD p-System before booting it. Those settings arestored in the last sector of the first disk's first track, track 0 512-byte sector 31, in the last 128-byte subsector (usually unused). Please note that the UCSD p-System works with 128-byte logical sectors,but the host Z80-MBC2 works using 512-byte physical sectors (FAT-32).

To access the setup menu, the USER button needs to be pressed while launching the p-System. Boot thesystem while holding the USER button down, keep the button down while pressing the number3 (to bootthe loader using the selected disk set) or4 (to boot the custom AUTOBOOT.BIN file).

A screen like this one will appear:

64K UCSD p-System IV.0 C/SBIOS V1.3 for Z80-MBC2, Copyright (C) 2019 by GmEsoftBuild: Sep 05 2019 - 09:36:01Scanning Volumes: [++++++++++++++++++++++++++++++++++++++++++++++++++]Available volumes:20:SYS1C     21:SYS2      22:INTERP    23:ADVX      24:ADVSRC    25:SYSCPM126:STARTUP   27:UTIL1     28:ASM1      29:STARTRK   30:GAMES     31:KBDB32:KBDBX     33:88SYS     34:88SYS     35:SYSCPM1   36:Z8SYS     37:INTCPM38:INTZ80    39:STARTUP   40:SYS1      41:STARTUP   42:SYS1      43:SYS344:SYSCPM1   45:UTIL1     46:UTIL1     48:ASM1      50:SYS1S     51:PASCAL180:88SYS     81:ASM1      82:ASM2      83:ASM3      84:INTCPM    85:STARTUP86:SYS1      87:SYS2      88:SYS3      89:SYSCPM1   90:UTIL1     91:UTIL2Select volume numbers (<T>ens, <U>nits, <ret> to accept):#04 20:SYS1C   ?#05 21:SYS2    ?#09 51:PASCAL1 ?#10 23:ADVX    ?#11 24:ADVSRC  ?#12 22:INTERP  ?Select BIOS Type (<S>BIOS, <C>BIOS, <ret> to accept):CBIOS?

The configurable settings are:

• the mapping of 6 logical UCSD p-System 'block' units (#4-#5,#9-#12) to 6 physical disk image filesDSn0xx.DSK: the value ofn is fixed, it is the disk set number; the value ofxx is in the range00-99;

• the type of BIOS:CBIOS andSBIOS:CBIOS must be selected if the boot disk image isCP/M Adaptive System andSBIOS must be selected if the boot disk image isFull Adaptive System. The jump vectorsand the registers used to exchange parameters between the system and the BIOS routines are different andincompatible (more info later about this).

1: Download the original disk image from the web. I chose to download them from the Z80-SIM page atClassicCmp.org,at this URL:http://www.classiccmp.org/cpmarchives/cpm/mirrors/www.unix4fun.org/z80pack/ftp/ucsd-iv.tgz

2: Extract the 2 disk images from the archive:ucsd-iv-1.dsk anducsd-iv-2.dsk.

3: Convert the disk images to the Z80-MBC2 format using the provided toolmakedisk (source code:makedisk.c):

makedisk -M:DS2N20.DSK -I:ucsd-iv-1.dsk -L:128 -SI:26 -SO:128 -F:T0 -T:T1 -D:T0 -F:T1 -T:T77 -D:T1 -P:T77makedisk -M:DS2N21.DSK -I:ucsd-iv-2.dsk -L:128 -SI:26 -SO:128 -F:T0 -T:T1 -D:T0 -F:T1 -T:T77 -D:T1 -P:T77

This will extract the first 26-sector track of the source images and copy the sectors to the first 128-sector trackof the new disk images. Then data from the tracks 2 to 77 from the source images to the new images starting from track2, adjusting for the new track size. Finally the images will be padded for the 1.2 megabytes capacity.

The syntax for makedisk is:

Makedisk -M:outfile [-L:lrl] [-SI:input track size] [-SO:output track size]             [ [-I:infile] [-XI:input interleave] [-KI:input skew]           -F:[T]from -T:[T]to -D:[T]dest ... ]         [ -P:[T]padsize ]             T for whole tracks, else sectorsDefaults:         -L:128   bytes per sector         -SI:26   sectors per side for input (8inch format)         -SO:128  sectors per side for output (Z80-MBC2 image format)         -XI:1    (no interleave)         -KI:0    (no skew)

4: Start the UCSP p-System.

5: Set today's date usingF(iler - D(ate.

Example:24-Aug-19

6: Extend the disk size of units#4 and#5 usingX(ecute - SYS2:DISKSIZE:

Change directory size of what unit? (4,5,9..12) --> 4, then 5What is the new directory size in 512 byte blocks ? --> 2432(=76*32)

7: Configure the p-System to the characteristics of the UTERM terminal (30 lines of 80 characters), so the scrollingin the editor will perform correctly, usingX(ecute - SETUP:

SETUP: C(hange T(each H(elp Q(uit --> CCHANGE: S(ingle) P(rompted) ... --> P--> reply N until getting FIELD NAME = SCREEN HEIGHT, then reply YNEW VALUE: --> 30Then reply N to the remaining prompts.Type L to check that the new value has been accepted.--> Q(uit) to exit change mode--> Q(uit) to save new settings --> D(isk), then E(xit)

The new settings are now saved toSYS1:NEW.MISCINFO. Rename this file toSYS1:SYSTEM.MISCINFO, overwriting the existingfile, usingF(iler - C(hng:

Change what file ? --> NEW.MISCINFOChange to what ? --> SYSTEM.MISCINFORemove old SYS1:SYSTEM.MISCINFO ? --> Y

8: Alter theGOTOXY procedure, to make it accept row numbers between1 and30.

F(iler - G(et the workfile --> gotoxyQ(uit the FilerE(ditChange line 13 to read:    IF Y>29 THEN Y:=29;(go over the 3; D(let, press the spacebar once then Ctrl-Z; I(nsrt, hit 9 then Ctrl-Z)Q)uit the editor and U)pdate the workfileC)ompile the fileF)iler - S)aveSave as SYS1:GOTOXY ? --> YQ)uit the Filer

Then bindGOTOXY into the system library:

X)exute --> SYS2:LIBRARYOutput file? --> NEW.PASCALInput file? --> GOTOXY--> T(ext (Interface sections will not be copied)--> 0From slot #? 0 --> spacebarTo slot #? --> 16--> N(ewInput file? --> SYSTEM.PASCAL--> E(very (get all slots except GOTOXY)--> Q(uit LIBRARY

Now using F)iler renameNEW.PASCAL toSYSTEM.PASCAL:

--> F)iler - C)hngChange what file ? --> NEW.PASCALChange to what ? --> SYSTEM.PASCALRemove old SYS1:SYSTEM.PASCAL ? --> Y--> K)rnch to compress the directoryCrunch what vol ? --> :From end of disk, block 2432  ? (Y/N) --> Y

Reboot the system. The p-System should now use all 30 UTERM's lines.

1: Download the ZMAC assembler from here (or usegetzmac.sh):http://48k.ca/zmac.html

2: ExecuteMAKEIT.BAT. This will create the fileautoboot.bin that will be copied to the SD card.