CP/M (Control Program/Monitor) is an operating system for 8-bit and 16-bit processors. It was the most famous operating system for 8-bit Intel 8080, Intel 8085 and Zilog Z80 processors. CP/M-68K is a CP/M operating system for Motorola 68000 and 68010 processors. It was used on the Motorola EXORmacs developments system, SORD M68 and M68MX computers. CP/M-68K was very uncommon operating system when compared to 8-bit CP/M-80 variant. Software availability is limited for the CP/M-68K, but the operating system includes for example an assembler and a C language compiler.
SturmBIOS (also known as cpm68k-amiga) is an implementation of CP/M-68K BIOS for Commodore Amiga. It allows the usage of CP/M-68K on Amiga 500, 600, 1000 and 2000 computers.
Note: This project is still in "work in progress" state. There are bugs and a new version can be buggier than a little bit older version. Testing is done mainly with UAE so that development is quicker. But real HW is planned to be supported.
CP/M-68k documentation can be found from https://github.com/juollila/cpm68k-amiga/tree/main/cpm/doc
It is recommended that new users read User's Guide. If a user wants program then Programmer's Guide and C Programming Guide are recommended.
A bootable disk image: https://github.com/juollila/cpm68k-amiga/blob/main/amiga/adf/cpm-boot.adf
| Start Address | End Address | Description |
|---|---|---|
| 00000 | 003ff | Exception vectors |
| 00400 | 5ffff | Transient program area |
| 60000 | 65fff | BDOS and CCP |
| 66000 | 7ffff | BIOS, disk buffer, screen buffer |
Amiga CP/M disk uses Amiga MFM sector format at the lowest level so that Amiga ADF utilities can be used to read and write physical disks. Amiga CP/M disk uses CP/M file system instead of Amiga file system (OFS, FFS or SFS).
The structure of disk:
| Start | End | Description |
|---|---|---|
| Track 0, sector 0 | Track 0, sector 1 | Boot loader |
| Track 0, sector 2 | Track 7, sector 10 | CCP, BDOS and BIOS |
| Track 8, sector 0 | Track 8, sector 7 | CP/M file system, directory area |
| Track 8, sector 8 | Track 159, sector 10 | CP/M file system, data area |
Disk definition for Cpmtools:
diskdef amiga
seclen 128
tracks 160
sectrk 44
blocksize 2048
maxdir 128
boottrk 8
os 2.2
endSturmBIOS support both ADM-3A and VT-52 terminal emulation.
| ADM-3a control codes: | Control code | Description |
|---|---|---|
| ^H or backspace | Cursor left / backspace | |
| ^I or TAB | Tabulator | |
| ^J | Line feed i.e. cursor down + scrolling if needed | |
| ^K | Cursor up / vertical tab | |
| ^L | Cursor right / form feed | |
| ^M | Carriage return | |
| ^Z | Move cursor home and clear screen | |
| ESC = row col | Move cursor position, add $20 to row and col |
| VT-52 control codes: | Control code | Description |
|---|---|---|
| ^H or backspace | Cursor left / backspace | |
| ^I or TAB | Tabulator | |
| ^J | Line feed i.e. cursor down + scrolling if needed | |
| ^K | Cursor up / vertical tab | |
| ^L | Cursor right / form feed | |
| ^M | Carriage return | |
| ^Z | Move cursor home and clear screen | |
| ESC A | Cursor up without scrolling | |
| ESC B | Cursor down without scrolling | |
| ESC C | Cursor right | |
| ESC D | Cursor left / backspace | |
| ESC H | Move cursor home | |
| ESC I | Cursor up + scrolling if needed | |
| ESC J | Erase to end of screen | |
| ESC K | Erase to end of line | |
| ESC Y col row | Cursor position, add $20 to col and row |
Amiga HW restrictions:
BIOS restrictions:
CP/M-68K's boot process is the following:
The following SW is required to compile Amiga BIOS for CP/M-68k and create a bootable disk image:
The following procedure can be used to create a new blank CP/M disk image:
diskdef amiga
seclen 128
tracks 160
sectrk 44
blocksize 2048
maxdir 128
boottrk 8
os 2.2
endmkfs.cpm -f amiga cpm-blank.adfNote: This image is not bootable.
Use the following commands to create a bootable floppy disk image after you have installed all requirements and added Amiga disk format to diskdefs of cpmtools:
$ cd amiga/bios
$ makeOr you may follow the manual procedure which is described in the following sections.
See also Makefile for further details.
CP/M binary distribution contains CCP and BDOS in Motorola S record format. It can be converted to binary format using for example SDCC compiler suite's sdobjcopy utility.
$ sdobjcopy --input-target srec --output-target binary cpm60000.SR cpm60000.binAmiga BIOS for CP/M-68k can be compiled using the following command.
$ vasmm68k_mot bios.asm -Fbin -o bios.binCP/M binary contains CCP, BDOS and BIOS. The starting address of CCP and BDOS (cpm60000.bin) is $60000 and starting address of BIOS is $66000. A padding must be added between cpm60000.bin and bios.bin. At first a padding file is created.
$ dd if=cpm60000.bin ibs=24k count=1 of=cpm60000-padded.bin conv=syncThe cpm.bin file is created concatenating cpm60000-padded.bin, padding.bin and bios.bin.
$ cat cpm60000-padded.bin padding.bin bios.bin > cpm.binAt first boot track binary is created using the following command. The binary contains boot loader, CCP, BDOS and BIOS.
$ vasmm68k_mot boot_loader.asm -Fbin -o boot.binCalculate and write Amiga boot block's checksum.
$ python3 checksum.py --output boot-with-checksum.bin boot.binBootable disk image is created copying boot track binary to a blank CP/M disk image:
$ cp cpm-blank.adf cpm-boot.adf
$ mkfs.cpm -f amiga -b boot-with-checksum.bin cpm-boot.adfCP/M programs can be copied to cpm-boot.adf using Cpmtools.
For example:
$ cpmcp -f amiga cpm-boot.adf program 0:CP/M-68K System Guide: https://github.com/juollila/cpm68k-amiga/blob/main/cpm/doc/CPM-68K_System_Guide_Jan83.pdf
Amiga Hardware Manual: http://amigadev.elowar.com/read/ADCD_2.1/Hardware_Manual_guide/node0000.html
SturmBIOS floppy drive routines were inspired by AROS and EmuTOS floppy drive implementations:
EmuTOS - Amiga specific funtions: https://github.com/emutos/emutos/blob/master/bios/amiga.c
AROS - Amiga HW floppy stuff: https://github.com/aros-development-team/AROS/blob/master/arch/m68k-amiga/devs/trackdisk/trackdisk_hw.c