Microsoft opens door to the past by releasing 86-DOS and PC-DOS 1.00

Antiques code show Microsoft has released the source for another of its relics. This time, it's 86-DOS 1.00 getting the open source treatment, and a whole lot more for retro enthusiasts.

The release comes a year after Microsoft set the source for MS-DOS 4.0 free, but it includes a lot more than just the bones of an old operating system.

According to a post by Microsoft's Stacey Haffner and Scott Hanselman, "The listings include sources to the 86-DOS 1.00 kernel, several development snapshots of the PC-DOS 1.00 kernel, and some well-known utilities such as CHKDSK."

"Not only were these assembler listings, but there were also listings of the assembler itself!"

It is quite the treasure trove of information, and a throwback to an era when printouts were your friend for storing source code. "Software history lives in code, yes," acknowledged the pair, "but also ...