Microsoft

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PC-DOS 1.00 would lead to Microsoft becoming computing's top dog

Microsoft continues to embrace open source.

The source code and annotations provide insight into the operating system's earliest days.

Before "Micro Soft" became Microsoft, Bill Gates wrote BASIC interpreters. Microsoft's first shipping operating system was a Unix distro called Xenix . Then, in 1980, Microsoft got its shot at the big time: IBM needed an operating system for its planned IBM PC and asked Gates if he could deliver one. You betcha! The rest is history.

Now, Microsoft has released the source code and notes for PC-DOS 1.00 , the first DOS release for the IBM PC.

Also: 5 ways your Windows updates are about to get a lot less painful

Microsoft's AT&T Unix license didn't give the company the leeway to port Xenix to the x86 IBM PC. That would have led to a very different world with Unix as the top desktop operating system from then until today.…