DOS Before DOS

January 3, 2024 9:04 PM

MS-DOS was famously based on QDOS, later known as 86-DOS. which Microsoft purchased in 1981. Version 0.1-C was discovered, making it the oldest known build (previously it was 0.34). This was likely the first after changing from the QDOS name. It was uploaded to the Internet Archive, and can be booted with the SimH Emulator.
posted by MrGuilt (16 comments total)

Someone needs to run Doom on this.
posted by neuron at 7:21 AM on January 4 [3 favorites]

Is this why the version of BASIC that shipped with early Windows was called QBASIC? I always wondered!
posted by potrzebie at 7:26 AM on January 4 [3 favorites]

The Ars piece links out to their history of the PC, which looks really interesting--am I to understand that Microsoft didn't actually create MS-DOS itself, it just licensed and rebranded 86-DOS?
posted by mittens at 7:44 AM on January 4

To run DOOM you'd have to port the DOS/4GW 32-bit extender, which requires the DPMI interface only available in MS-DOS 4.0 and above. You could use EMS and modify DOOM to use a bank-switching approach, but surely no nerd could be nerdsniped that badly...
posted by credulous at 7:57 AM on January 4 [5 favorites]

mittens, that’s exactly what happened. Gates licensed, then bought, 86-DOS to make PC-DOS, which they licensed to IBM. They then sold MS-DOS to clone manufacturers, and subsequently continued to develop it.

Is this why the version of BASIC that shipped with early Windows was called QBASIC?

QBASIC didn’t ship until MS-DOS 5 (1991). Prior to that, it was GW-BASIC, which was derived from BASICA
posted by MrGuilt at 7:57 AM on January 4 [8 favorites]

I always thought QBASIC was a stripped down version of Microsoft's QuickBASIC.
posted by Blienmeis at 9:21 AM on January 4 [1 favorite]

Blienmeis It was, aimed at giving DOS users something better than the BASICA/GW-BASIC line. The latter was…spare, to say the least.
posted by MrGuilt at 9:24 AM on January 4

Didn't BASICA require a ROM that was only present in the original IBM-PC?

I think later versions of MSDOS had a special error message if you tried to run basica.
posted by RonButNotStupid at 9:28 AM on January 4

This is a good video of this version 86-DOS actually being used as it would be back in the day: porting a Z80 assembly program written for CP/M over to 86-DOS. The end also has an interesting tangent at the end addressing claims that 86-DOS was based on stolen CP/M source code (spoiler: it wasn't, it just reimplements calls to make porting easier).
posted by zsazsa at 9:50 AM on January 4 [3 favorites]

Didn’t BASICA require a ROM that was only present in the original IBM-PC?

I don’t know about the ROM, but BASICA was an IBM product, and included with PC-DOS, where MS-DOS shipped with Microsoft’s clone, GW-BASIC. AFAIK, it was a licensing thing.
posted by MrGuilt at 11:00 AM on January 4

The Digital Antiquarian has a great series of posts about the development of 86/Q/PC/MS-DOS (actually about the development of the IBM PC), starting here (but really at the end of part 2). It's actually some fascinating stuff, full of intrigue and backstabbing.
posted by General Malaise at 11:56 AM on January 4

I wonder what the parallel universe where IBM got a CP/M license would've looked like.
posted by BrotherCaine at 3:33 PM on January 4

I might have to reread, both links and comments, to catch all the details, but this is fascinating—thanks for posting!
posted by box at 5:07 PM on January 4 [1 favorite]

Sorta unrelated, but I used a version of IBM DOS back in the 70s. On a mainframe, not the PC version so named in the 80s. Disk Operating System. and Wiki just can find a reference to IBM DOS/VS.
posted by baegucb at 6:45 PM on January 4

I don't think DOS/360 for mainframes is related to PC-DOS/MS-DOS other than the name and that IBM sold both.
posted by grouse at 12:57 PM on January 5

I worked at Microsoft at the same time as Tim Paterson. The Seattle Times wrote some article that implied that Tim had been shafted by Microsoft and likely panhandling to get by. He taped a cup to his office door so people could donate to his Porsche maintenance fund.
posted by Xoc at 6:24 PM on January 5 [4 favorites]