BetaWiki

I worked on MS-DOS, but not this one! Microsoft has open-sourced MS-DOS 4.00 on Github, but it might not be what you think it is. MS-DOS 4.00 was an attempt at a multitasking MS-DOS, but OEMs weren't really interested, and it was only ever in limited release. So it's almost certainly not the one you used back in the day. MS-DOS 4.01, on the other hand, was the one you all know and "love". Actually, it was much maligned. It included the DOSSHELL. People did not love it, as opposed to MS-DOS 5 and 6, which were very well received! More info can be found on Scott Hanselman's site: hanselman.com/blog/open-sour……

Windows Longhorn Build 4074, the most widely known (and arguably the most usable) build of Longhorn turns 20 years old today

To end this thread, one Windows component still shipping today can trace its history directly back to multitasking DOS 4.0 - the Command Prompt. cmd.exe was originally ported from OS/2, which in turn is directly based on the DOS 4.0 COMMAND.COM!

The design of multitasking DOS 4.0 does in fact share some similarities with OS/2. The DOS kernel exports certain APIs via a NE module called DOSCALLS. The process information structure is the same in both systems. They both also handle errors via a resident hard error daemon.

Did you know? In 1986, Microsoft released a version of MS-DOS which supported preemptive multitasking for compatible applications. This version was called MS-DOS 4.0 and is completely unrelated to the proper, widespread version of MS-DOS 4.0 from 1988!

@dm4uz3 why is this how I find out MS-DOS is open-source

look between B and W on your keyboard

Credit goes to @jeffpar for sharing this build, and to @hyenaskyy, @substanc3dev and others for working hard to make this obscure build work in an emulator!

"Just say WOW!" Presenting the Windows NT "WOW Reversi MIPS Demo", currently the earliest available NT build. This build was compiled in early April 1991 as an early demonstration of Win16 apps running under emulation on a non-x86 machine.

Geoff Chappell passed away today on his own terms, surrounded by family and while his good humor remained intact. Please listen to a Beatles record and read a little assembly code in his honor.