SvarDOS community forum

Yes, It's true. https://www.hanselman.com/blog/open-sourcing-dos-4

Thanks for the news, that's very cool indeed. The source code has been published in the Microsoft github repo along with versions 1.25 and 2.0 of MS-DOS: https://github.com/Microsoft/MS-DOS MS-DOS 4.0 was an odd duck, so I doubt this release will be of any practical use, but it will certainly help with understanding compatibility corner cases. What I'm really waiting for is the release of either version 3.x or 5.x, as these could be integrated within SvarDOS as alternative kernels. Mateusz

They've released both the source for the MT version (multitasking) which I think is what you're referring to as the "odd duck" but also the regular DOS 4.01 source which is the basis for PC-DOS 4.01. Unlike 1.25 and 2.0 it has hard disk support up to 2Gb. I would say it's of practical use on an XT or 286. They've included the appropriate MASM, LINK and Microsoft C to build it. Neozeed with the help of the OS/2 museum guy has compiled and booted it successfully on qemu. https://github.com/neozeed/dos400/releases/tag/v_0.2

> They've released both the source for the MT version (multitasking) which I think is what you're referring to as the "odd duck" but also the regular DOS 4.01 source which is the basis for PC-DOS 4.01.

AFAIK, there's no source code for MT-DOS, but early beta binaries only. Citing https://cloudblogs.microsoft.com/opensource/2024/04/25/open-sourcing-ms-dos-4-0/ "[...] and while they were unable to find the full source code for MT-DOS, they did find MS DOS 4.00, which we’re releasing today, alongside these additional beta binaries [...]"

One thing we could import would be the original Microsoft EDLIN. While Gregory made an awesome job of putting together a portable clone written in C, it is a rather large binary, and it differs slightly in functionality.

If we are lucky, they will eventually open source MS-DOS 5. Then SvarDOS will have its third kernel package (after FreeDOS and EDR kernel) within 48 hours :-D

> One thing we could import would be the original Microsoft EDLIN. While Gregory made an awesome job of putting together a portable clone written in C, it is a rather large binary, and it differs slightly in functionality.

Having it in core is probably a waste of space, but why not adding it as a non-core package, say "MSEDLIN", for users that have some sentimental need to use it. :) Any volunteers? Mateusz

Yes, having it in core was not my intention. Would be nice to have a package for it. I can do it. But building the DOS 4 EDLIN out of tree is a pain. They overcomplicated it by introducing a new message translation mechanism. That is so braindead that this part of the code must have come from IBM. I have building the DOS 2 EDLIN out of tree with JWASM. Have to look at the differences to see if the changes in the DOS 4 version are crucial. Interesting fact is that the EDLIN DOS 2 source does not match the binary in their repository (2.14 source vs. 2.0 binary).