Long shot, but.. I'm attempting to make some changes to the ATR8000 bios. My starting point is the ATR8000 bios (attached), which offers no
real changes but is meant as an exercise in rebuilding the BIOS before I start making the real changes.
The process I'm following is to first generate a custom CP/M using
and write the tracks to disk, then boot from that disk.
We find that the BIOS starts at DA00h following the configuration.
Then, I org the BIOS source at C400h, and compile using SLR180/hf to produce a hex file and a listing.
And that's where the fun begins. When I compare the compiled bios to what should be the running bios,
I see that the running bios matches, and then all of a sudden, we see the compilation listing:
241 ; ... cold boot entry point ...
243 DA59 BOOT:
244 DA59 2A F019 LD HL,(MONITOR+24+1)
245 DA5C 22 F7EB LD (REINIT+1),HL ;set address for console re-init
246 DA5F 21 F7EA LD HL,REINIT ;patch new address in monitor vector
247 DA62 22 F019 LD (MONITOR+24+1),HL
249 DA65 21 DA83 LD HL,BOOTAB
250 DA68 CD DB08 CALL MOVE ;store constants from boot init table
252 DA6B 01 0DA3 LD BC,10100011B OR (13 SHL
253 DA6C IBAUD EQU $-2 ;initial baudrate for rs232 port
254 DA6E CD F70C CALL OVRLAY+12 ;go program rs232 port
256 DA71 21 F880 LD HL,DIRBUF
257 DA74 CD DF48 CALL PMSG ;display signon message in temp buffer
259 DA77 21 DB16 LD HL,DUMMY
260 DA7A 22 DA01 LD (CBIOS+1),HL ;close the door on the way out
261 DA7D 21 C400 LD HL,CCP
262 DA80 E5 PUSH HL ;put ccp entry address onto stach
263 DA81 18 5B JR GOCPM
However, the running bios matches up to DA6E, but then seems to do something quite different.
DA71 96 SUB M
DA72 F3 DI
DA73 86 ADD M
DA74 F3 DI
DA75 312E9A LXI SP,9A2E
DA78 F202F3 JP F302
DA7B 00 NOP
DA7C 00 NOP
DA7D EDF7 ??=EDF7
DA7F 19 DAD D
DA80 F1 POP PSW
DA81 21DF00 LXI H,00DF
DA84 FD ??=FD
DA85 0C INR C
DA86 DF RST 3
DA87 86 ADD M
DA88 DE8D SBI 8D
DA8A DD ??=DD
DA8B 51 MOV D,C
DA8C DA00FD JC FD00
DA8F 3B DCX SP
So, to make a long story short, if you have an ATR8000 bios (4-84), I'd love to see it to compare with the attached.
And if you were an ATR8000 owner with a hard-disk, I'd *really* love to see the bios.