3 ms·

86-DOS Revisited

81 points by ingve 3y ago

snvzz 3y ago
Complete with disk images[0] for preservation proper. Bless archivists. 0. http://www.bitsavers.org/bits/SeattleComputerProducts/86-DOS/ http://www.bitsavers.org/bits/SeattleComputerProducts/86-DOS...
hilbert42 3y ago
I had a copy of this as Seattle Ccomputer Products O/S that I purchased from Lifeboat Associates in NY on an 8" floppy. It was used to run my CompuPro S100 system (I used it with my dual processor (8085/86) board along with CP/M-80. Those were the days when we had to compile the BIOS—I still have the ASM file for that somewhere it's called HMXBIOS.ASM if I recall correctly. It's nice to know someone has archived the O/S and that there's a link to it—thanks snvzz.
rwmj 3y ago
I think we need to know more about why the disk has "BILL" written in the corner.
- DeathArrow 3y ago
  It probably belonged to Bill Gates.
TedDoesntTalk 3y ago
Where did it emerge from? No mention… Sometimes the story of how it was acquired it just as interesting.
- kjs3 3y ago
  Sometimes people don't want others to know how they got it.
- qingcharles 3y ago
  This has happened infuriatingly often lately. Some disk image from history just suddenly turns up on github with little knowledge of how it got there. These are 8" disks, so someone not only found the disks but had the setup to read the disks and dump the binaries.
- polpo 3y ago
  The person who imaged the disks commented on this video exploring 86-DOS 0.11: https://www.youtube.com/watch?v=Zd7T5euID1E https://www.youtube.com/watch?v=Zd7T5euID1E (It's a neat video by the way – he shows how 86-DOS would be used in that state back then by creating a Z80 "Hello World" program in CP-M, copying it over with RDCPM, translating it to 8086 assembly with TRANS, tweaking the source with EDLIN, assembling with ASM and HEX2BIN, and running it.)
- lproven 3y ago
  I give some detail in my article on the find: https://www.theregister.com/2024/01/05/oldest_ancestor_of_msdos_recovered/ https://www.theregister.com/2024/01/05/oldest_ancestor_of_ms...
anonymousiam 3y ago
"; Translated from the Z80 on 12-19-80 and subsequently upgraded to handle ; all of the following controllers. Set switch to one to select." Despite Tim Patterson, and later Bill Gates trying to pretend that DOS was a wholly new creation, the first comment re-confirms what everyone knew at the time -- that DOS was a cross-assembler translation of the leaked CP/M source code with some very minor changes (INT 5 vs. CALL 5). https://archive.org/details/bitsavers_seattleComsemblerPreliminary_611077 https://archive.org/details/bitsavers_seattleComsemblerPreli... https://www.theregister.com/2007/07/30/msdos_paternity_suit_resolved/ https://www.theregister.com/2007/07/30/msdos_paternity_suit_... https://www.theregister.com/2014/10/02/cpm_source_code_release/ https://www.theregister.com/2014/10/02/cpm_source_code_relea... http://www.s100computers.com/Hardware%20Folder/Seattle%20Computer%20Products/History/History.htm http://www.s100computers.com/Hardware%20Folder/Seattle%20Com... https://www.wired.com/2012/08/ms-dos-examined-for-thef/ https://www.wired.com/2012/08/ms-dos-examined-for-thef/
- rep_lodsb 3y ago
  86-DOS was modeled after CP/M, with separate BIOS (hardware drivers) and BDOS (filesystem) modules. What was translated from Z80 is likely the BIOS code, since SCP already had written that before the 8086 CPU card existed. And all versions supported both CALL 5 and INT 21h for system calls (not 5, which was reserved by Intel, though IBM didn't care about that when they designed the PC and used it for "print screen"). That doesn't mean the implementation was based on leaked CP/M code, let alone literally translated.
  - anonymousiam 3y ago
    CP/M consists of three parts, CCP = Console Command Processor, BDOS = Basic Disk Operating System, BIOS = Basic Input Output System. SCP copied the CCP and BDOS. The BIOS would be the most hardware-centric part of CP/M, and would probably not be copied between platforms. Also, the BIOS was the only "open" part of CP/M. You are correct that DOS uses INT 21 and not INT 5. Sorry for my typo. The INT 21 vs CALL 5 APIs are effectively identical aside from the calling mechanism. I never did it, but I think it would have been interesting to run the SCP cross-assembler on the leaked CP/M CCP and BDOS. (They would need to be translated from Intel mnemonics into Zilog ones, but there are tools for that too.) After using the automated tools, I believe the resulting x86 assembly source would be "substantially similar" to the early DOS source.

81 points by ingve 3y ago

Complete with disk images[0] for preservation proper. Bless archivists. 0. http://www.bitsavers.org/bits/SeattleComputerProducts/86-DOS/ http://www.bitsavers.org/bits/SeattleComputerProducts/86-DOS...

hilbert42 3y ago

I had a copy of this as Seattle Ccomputer Products O/S that I purchased from Lifeboat Associates in NY on an 8" floppy. It was used to run my CompuPro S100 system (I used it with my dual processor (8085/86) board along with CP/M-80. Those were the days when we had to compile the BIOS—I still have the ASM file for that somewhere it's called HMXBIOS.ASM if I recall correctly. It's nice to know someone has archived the O/S and that there's a link to it—thanks snvzz.

rwmj 3y ago

I think we need to know more about why the disk has "BILL" written in the corner.

DeathArrow 3y ago
It probably belonged to Bill Gates.

TedDoesntTalk 3y ago

Where did it emerge from? No mention… Sometimes the story of how it was acquired it just as interesting.

kjs3 3y ago
Sometimes people don't want others to know how they got it.
qingcharles 3y ago
This has happened infuriatingly often lately. Some disk image from history just suddenly turns up on github with little knowledge of how it got there. These are 8" disks, so someone not only found the disks but had the setup to read the disks and dump the binaries.
polpo 3y ago
The person who imaged the disks commented on this video exploring 86-DOS 0.11: https://www.youtube.com/watch?v=Zd7T5euID1E https://www.youtube.com/watch?v=Zd7T5euID1E (It's a neat video by the way – he shows how 86-DOS would be used in that state back then by creating a Z80 "Hello World" program in CP-M, copying it over with RDCPM, translating it to 8086 assembly with TRANS, tweaking the source with EDLIN, assembling with ASM and HEX2BIN, and running it.)
lproven 3y ago
I give some detail in my article on the find: https://www.theregister.com/2024/01/05/oldest_ancestor_of_msdos_recovered/ https://www.theregister.com/2024/01/05/oldest_ancestor_of_ms...

anonymousiam 3y ago

"; Translated from the Z80 on 12-19-80 and subsequently upgraded to handle ; all of the following controllers. Set switch to one to select." Despite Tim Patterson, and later Bill Gates trying to pretend that DOS was a wholly new creation, the first comment re-confirms what everyone knew at the time -- that DOS was a cross-assembler translation of the leaked CP/M source code with some very minor changes (INT 5 vs. CALL 5). https://archive.org/details/bitsavers_seattleComsemblerPreliminary_611077 https://archive.org/details/bitsavers_seattleComsemblerPreli... https://www.theregister.com/2007/07/30/msdos_paternity_suit_resolved/ https://www.theregister.com/2007/07/30/msdos_paternity_suit_... https://www.theregister.com/2014/10/02/cpm_source_code_release/ https://www.theregister.com/2014/10/02/cpm_source_code_relea... http://www.s100computers.com/Hardware%20Folder/Seattle%20Computer%20Products/History/History.htm http://www.s100computers.com/Hardware%20Folder/Seattle%20Com... https://www.wired.com/2012/08/ms-dos-examined-for-thef/ https://www.wired.com/2012/08/ms-dos-examined-for-thef/

rep_lodsb 3y ago
86-DOS was modeled after CP/M, with separate BIOS (hardware drivers) and BDOS (filesystem) modules. What was translated from Z80 is likely the BIOS code, since SCP already had written that before the 8086 CPU card existed. And all versions supported both CALL 5 and INT 21h for system calls (not 5, which was reserved by Intel, though IBM didn't care about that when they designed the PC and used it for "print screen"). That doesn't mean the implementation was based on leaked CP/M code, let alone literally translated.
- anonymousiam 3y ago
  CP/M consists of three parts, CCP = Console Command Processor, BDOS = Basic Disk Operating System, BIOS = Basic Input Output System. SCP copied the CCP and BDOS. The BIOS would be the most hardware-centric part of CP/M, and would probably not be copied between platforms. Also, the BIOS was the only "open" part of CP/M. You are correct that DOS uses INT 21 and not INT 5. Sorry for my typo. The INT 21 vs CALL 5 APIs are effectively identical aside from the calling mechanism. I never did it, but I think it would have been interesting to run the SCP cross-assembler on the leaked CP/M CCP and BDOS. (They would need to be translated from Intel mnemonics into Zilog ones, but there are tools for that too.) After using the automated tools, I believe the resulting x86 assembly source would be "substantially similar" to the early DOS source.