Add minimal CP/M 2.2 BIOS implementation and BDOS support #3
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ericTheEchidna
commented
Nov 25, 2025
ericTheEchidna
commented
- Introduced a basic BIOS for the emulator, providing console I/O and stubs for disk routines.
- Implemented a jump table for standard CP/M functions.
- Added necessary data structures and constants for BIOS operations.
- Created a new BDOS symbol file with function addresses and constants.
- Updated CCP symbol file with relevant constants and addresses.
- Introduced a basic BIOS for the emulator, providing console I/O and stubs for disk routines. - Implemented a jump table for standard CP/M functions. - Added necessary data structures and constants for BIOS operations. - Created a new BDOS symbol file with function addresses and constants. - Updated CCP symbol file with relevant constants and addresses.
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Pull request overview
This PR introduces a minimal CP/M 2.2 BIOS implementation and BDOS support for the emulator, establishing a fixed memory layout with BDOS at 0xE000, CCP at 0xE900, and BIOS at 0xF200.
- Replaced dynamic origin calculations with explicit address constants for predictable CP/M memory layout
- Converted assembly syntax from 8080 mnemonics to Z80 equivalents throughout CCP and BDOS modules
- Created a minimal BIOS with console I/O via port 0 and stub disk routines that return success without actual disk operations
Reviewed changes
Copilot reviewed 5 out of 6 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| bios.asm | New minimal BIOS implementation with console I/O, disk stubs, and jump table at 0xF200 |
| bios.sym | Symbol file for BIOS entry points and data addresses |
| bdos.asm | Converted to Z80 syntax and fixed BDOS address at 0xE000, removed conditional ORG logic |
| bdos.sym | Symbol file with BDOS function addresses and constants |
| ccp.asm | Converted to Z80 syntax and fixed CCP address at 0xE900, removed origin calculation |
| ccp.sym | Symbol file with CCP addresses and constants |
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| settrkf equ bios+3*10 ;EQU track function | ||
| setsecf equ bios+3*11 ;EQU sector function | ||
| setdmaf equ bios+3*12 ;EQU dma function |
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Inconsistent comment style: "EQU" is used instead of "set" in comments. Lines 52-54 use "EQU" (uppercase) in comments like ";EQU track function" which is confusing since EQU is an assembler directive. These should be ";set track function" or ";settrkf function" to match the naming convention.
| settrkf equ bios+3*10 ;EQU track function | |
| setsecf equ bios+3*11 ;EQU sector function | |
| setdmaf equ bios+3*12 ;EQU dma function | |
| settrkf equ bios+3*10 ;set track function | |
| setsecf equ bios+3*11 ;set sector function | |
| setdmaf equ bios+3*12 ;set dma function |
| @@ -2969,5 +2943,8 @@ dptr: ds byte ;directory pointer 0,1,2,3 | |||
| dcnt: ds word ;directory counter 0,1,...,dirmax | |||
| drec: ds word ;directory record 0,1,...,dirmax/4 | |||
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| bios equ ($ & 0ff00h)+100h ;next module | |||
| bios equ 0C000h;next module | |||
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Missing space after "equ" directive. The line should be bios equ 0C000h ;next module (with a tab before the comment) to match the spacing convention used elsewhere in the file.
| bios equ 0C000h;next module | |
| bios equ 0C000h ;next module |
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