Linked by Thom Holwerda on Tue 25th Mar 2014 17:17 UTC, submitted by MOS6510
Microsoft

The Computer History Museum announced today that it has, with permission from Microsoft Corporation, made available original source code for two historic programs: MS-DOS, the 1982 "Disk Operating System" for IBM-compatible personal computers, and Word for Windows, the 1990 Windows-based version of their word processor.

Great move by Microsoft - this ensures these programs remain available for eternity.

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RE[4]: And now, the truth...
by biffuz on Wed 26th Mar 2014 16:36 UTC in reply to "RE[3]: And now, the truth..."
biffuz
Member since:
2006-03-27

Actually even DOS had the concept of "tasks", just looking at the output of mem (mem /c if I recall correctly) would tell you this. The trouble was DOS did not use an MMU in low memory, so it was impossible for tasks (TSRs) to resize their low memory footprint on the fly. However those that used expanded memory via EMM386/QEMM could alloc/free memory in the background. TSRs could even multitask, for example I had a music player that could open/play .mod files while using other dos programs.


They were not tasks, because they didn't have a running status or something like that. They were called "modules" for a reason.
Those "multitasking" TSRs came with their own code to do that (that is, they replaced the clock's interrupt handler). Heck, there was an example on my Turbo Pascal book, the second programming book I read when I was 12.


Far be it for me to suggest it that DOS was any good at multitasking, it was not. However initially windows was built on DOS and EMM386 and DOS interrupt calls, etc. It depended on DOS based file systems drivers, packet drivers, COM, etc.


I'm not sure about all of this... but I don't want to check everything. Anyway, its dependency declined over the years.

"And let's not dive into 9x, which had a (mostly) 32 bit kernel. DOS had no kernel at all!


No kernel at all?
"

Yep. DOS is more like a bunch of interrupt handlers with a library. Nothing we can define a kernel.

"* quite primitive compared to today standards, but still much more than DOS could dream of.


DOS was simple, but it was still an OS at a time when Windows was not an OS and needed DOS.
" [/q]

That's an interesting question, DOS is far from an OS in today's terms, but Windows couldn't run without it, so the real OS was DOS+Windows, isn't it?

Now it would be interesting if Microsoft releases the Windows 1.x source code ;)

Anyway, I downloaded that Word source... just let me set up a Windows 3.1 VM, install Visual C++ 1.something (I have it somewhere) and let's see if I can compile it!

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