Microsoft releases source code to MS DOS 1.1 and 2.0 and Word for Windows 1.1a

In this age of touchscreen and voice command interfaces, it's sometimes hard to believe that less than 40 years ago, we just used keyboards to interact with our personal computers. Today, Microsoft gave us a helpful reminder of that fact by announcing it is making the original source code for MS DOS 1.1 and 2.0 and Word for Windows 1.1a to the public for the first time.

In a blog post, Microsoft says it worked with the Computer History Museum on this project. Roy Levin, the distinguished engineer and managing director for Microsoft Research, stated, "Thanks to the Computer History Museum, these important pieces of source code will be preserved and made available to the community for historical and technical scholarship." The source code can be found on the group's website for MS DOS 1.1 and 2.0 and for Word for Windows 1.1a. People who choose to download the code must agree to use it for non-commercial purposes; the code may also not be posted anywhere else on the Internet.

In July 1981, Microsoft made a deal with Seattle Computer Products​ to buy the full rights to its QDOS (Quick and Dirty Operating System) for $50,000. The OS was renamed MS DOS and was installed on all IBM PCs soon afterward. Microsoft retain the rights to sell MS DOS to other PC companies. That was the start of its rise that lead to its OS domination of the PC market.

Source: Microsoft | Image via Microsoft

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47 Comments

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Finally downloaded the source now that the site is no longer swamped.

I like how I could download the source to an entire OS in less time than I needed to pick what folder to download it to.

Now the next step would be to release source code of Win 8 so someone can strip out Metro out of it and release good clean version.

Auditor said,
Now the next step would be to release source code of Win 8 so someone can strip out Metro out of it and release good clean version.

Good luck getting support for your forked Windows 8 version.

_dandy_ said,

Good luck getting support for your forked Windows 8 version.

I don't need their support anyway with a source code in hand. LOL

Auditor said,
I don't need their support anyway with a source code in hand. LOL

Problem is, that sort of thing becomes a full-time job. For what little I see of Metro in my day-to-day use of Windows 8, I'd rather ignore it and instead work on my stuff.

Cool from a historical standpoint, I wonder what license the source was released under and if there are any weird non-compete clauses like the ones you have to agree to in Visual Studio?

It's part of the header, different versions will have different letters (LX, LE, PE, etc), if I remember right MZ was the initials of one of the creators of MSDOS.

Brian Miller said,
What does the frist 2 bytes of any EXE file mean, it read "MZ"?
Huh, thought most people visiting tech sites would know this. MZ = Mark Zbikowski

patseguin said,
Who would care anything about DOS source code?

You obviously don't but many people (who have spent years using it) would be very interested in looking at it, myself included.

patseguin said,
Who would care anything about DOS source code?

Anyone interested in computer history I would imagine, or people interested in programming.

Obry said,
You obviously don't but many people (who have spent years using it) would be very interested in looking at it, myself included.

Agreed. I started learning more serious programming with DOS--having the source back then would've been awesome.

I'll probably have a look in my free time as I'm sure it'll still be an interesting read.

I hope you like assembler ;) Poor souls having to write a whole OS in assembler using such primitive tools (by today's standards). I wonder what it took to debug this stuff back then. And sounds like source control meant printing the source code on sheets of paper lol

The Word 1.1 code is written in C at least so it is a little more readable.

Obry said,
I hope you like assembler

I know it, but I honestly wish I knew it better. I'd be better developer for it today.

Obry said,
I wonder what it took to debug this stuff back then.

It required knowing your sh*t. Way, way too many developers nowadays have no idea what's really going on behind the scenes, and have absolutely no clue where to start debugging when they encounter a problem that goes beyond some variable initialization.

These are the people who can only move forward in their career because as time progresses, CPUs get more powerful and they get more RAM to waste on their bloatware. A garbage collector is a poor substitute for not wasting resources to begin with. You might not write much assembler today, but just knowing it teaches you always, always think about those things.

Obry said,
And sounds like source control meant printing the source code on sheets of paper lol

Device driver and kernel mode development still takes place today. Source control works just as well for assembler as it does for any other language.

Edited by _dandy_, Mar 26 2014, 3:11pm :

Who said MS wasn't for open source? This is going to dominate Linux pretty soon. Waiting for Windows 3.0 source and Ubuntu is finished.

alright, dumb question, if they released the source code, does that give you the rights to compile and run it? just for play of course... I assume so considering they said for non-commercial use

it'll load, you just have to spam refresh pretty hard. it took me a few minutes to get it going, but it finally loaded and I was able to download. ;)

Krome said,
I wait for Windows XP source code :)
Goddangit! "503 Service Unavailable" Can't view that site.

If you work in education, you can already gain limited access to NT's source code for instruction purposes.

Krome said,
I wait for Windows XP source code :)

My first thought, when I read the headline, was to post a message saying "Cue the requests for XP in 3...2...1..."

Was not disappointed.

Krome said,
I wait for Windows XP source code :)
Goddangit! "503 Service Unavailable" Can't view that site.

You need to wait maybe 10 or 20 years from now.
Actually if Microsoft can release some part of the code is good enough. Especially the ones related to the security
So user can improve the security of the windows much better

utomo said,
Actually if Microsoft can release some part of the code is good enough. Especially the ones related to the security
So user can improve the security of the windows much better
Given all the things that can be potential attack surfaces in an OS, you really think the part of the code related to "security" is something entirely separate that you can then patch and replace in your copy of XP? :rolleyes: