Microsoft Open-Sources MS-DOS 4.0 Under MIT License

[phoronix]

Phoronix: Microsoft Open-Sources MS-DOS 4.0 Under MIT License

After publishing open-source versions of MS-DOS years ago for versions 1.25 and 2.0, Microsoft and IBM have now announced that MS-DOS 4.0 has been open-sourced under an MIT license...

https://www.phoronix.com/news/MS-DOS-4.0-Open-Source

[kpedersen]

Quite interesting, included is an early beta of Multi-tasking DOS. Which came from one of the previous top guys at Microsoft (Ray Ozzie) whilst rummaging around his collection.

(Ray Ozzie, took over from Bill Gates as Chief Software Architect for a short while, I spoke to him a couple of times during the XNA era, he was interesting and technical and not your typical "Corporate Microsoft Evangelist")

It makes you wonder what ancient gold other veterans have squirreled away on rotting disks in the attic! Please, everyone, release the code if you no longer plan to do anything commercial with it!

[Malsabku]

Can ReactOS perhaps benefit from this in some way?

[OneTimeShot]

Wouldn’t it make more sense to release the last version? It’s not like people won’t buy Windows 11 because they get MSDOS for free…

[uid313]

Maybe they can release MS-DOS 5 and 6 too?

[kpedersen]

Wouldn’t it make more sense to release the last version? It’s not like people won’t buy Windows 11 because they get MSDOS for free…

It would seem that way but MS-DOS 6 as well as adding features, actually removed features too. So in terms of digital archeology it is pretty much of equal value.

A very specific example of what was removed (and my main interest in this source drop) is DOS Shell (.com). One of the first task switchers for DOS.

Introduced in DOS 4.x but removed after 5.x (it was moved to a "supplementary pack" instead). I have been wondering how that thing worked for ages and maybe I can finally work out why my PC emulator consistently failed to work with it.

Edit: I have only briefly scanned through the sources but alas, DOSSHELL looks to be missing. It contained some early Windows 3.1 code so perhaps it was part of a different source tree. However the source to SHARE.EXE is there which was next on my list.

[alexvoda]

Wouldn’t it make more sense to release the last version? It’s not like people won’t buy Windows 11 because they get MSDOS for free…

Frankly, they could release all the way up to Windows ME.

[Volta]

Another useless trash from Microsoft. At least this one is free unlike Windows 11.

[schmidtbag]

kpedersen Pretty interesting posts you made. I wouldn't have thought of DOS 4 being roughly equally as good as 6, but since there were distinct pros and cons, it still gets you to wonder why MS only opened up 4 (and apparently 1.25 and 2.11)


I also wonder if DOSBox may benefit from this at all. I get the impression the project is pretty much complete, but that doesn't mean there aren't still more features to take advantage of.

[kpedersen]

I wouldn't have thought of DOS 4 being roughly equally as good as 6

Indeed. Actually using it, MS-DOS 6 was better (mainly because more software was available for it IMO). I imagine Microsoft isn't releasing it yet because there are still some very niche areas (very much legacy) that still use 6.x. But this is shrinking and I am sure Microsoft will release it at some point.

I am a retro fan (specifically the DOS era) and FreeDOS is ultimately the best, but still just feels like a big old messy bundle of freeware! MS-DOS may be inferior in many ways but it offers a cleaner "authentic" experience. So I do hope they release it (in my lifespan )

I also wonder if DOSBox may benefit from this at all. I get the impression the project is pretty much complete, but that doesn't mean there aren't still more features to take advantage of.

DOSBox is pretty much complete (DOSBox-X and things have forked from it for those who want "more"). Amusingly, from a low level, DOSBox is actually quite distinct from DOS. Up to a certain point it is all quite simulated rather than emulated (only the x86 CPU is fully emulated) so can't share too much code with actual DOS. Kind of like the HLE bios for Playstation emulators. Compatibility suffers a little for software that does "weird" things (admittedly, outside of games, DOS software does this a lot) but you do get a boost in performance.