Tag Archives: Gary Kildall

Was the Microsoft Empire Built on Stolen Goods?

The history of the computer industry is filled with fascinating tales of sudden riches and lost opportunities. Take that of Ronald Wayne, who cofounded Apple Computer with Steve Wozniak and Steve Jobs but sold his shares for just US $2,300. And John Atanasoff, who proudly showed his digital computer design to John Mauchly who later codesigned the Eniac, typically recognized as the first electronic computer, without credit to Atanasoff. Perhaps the most famous story of missed fame and fortune is that of Gary Kildall. A pioneer in computer operating systems, Kildall started the company Digital Research and wrote Control Program for Microcomputers (CP/M), the operating system used on many of the early hobbyist personal computers, such as the MITS Altair 8800, the IMSAI 8080, and the Osborne 1, before IBM introduced its own PC. Kildall could have been the king of personal computer software, but instead that title went to his small-time rival Bill Gates. For years, rumors have circulated that the code for the original DOS operating system sold by Microsoft is actually copied from the CP/M operating system developed by Digital Research.

A couple years ago we took it upon ourselves to search out the original code and use CodeSuite to determine the truth once and for all. Our research was summarized in a popular (and not-so-popular) article in IEEE Spectrum entitled Did Bill Gates Steal the Heart of DOS? If you haven’t read it, you should. It’s a fun read but it only summarizes our exhaustive results using our tools and procedures for finding copied code. The article generated a lot of controversy and we always intended to publish the full technical details of our analysis, but it’s surprising how many people don’t like our conclusion and wouldn’t publish my paper. But now the full academic paper entitled A Code Correlation Comparison of the DOS and CP/M Operating Systems is available online in the Journal of Software Engineering and Applications. If you want to know the details, and you want to know the truth, it’s in the article and the details are in the paper.