Gary Kildall started Intergalactic Digital Research (later shortened to Digital Research or just DRI) and created the first microcomputer operating system, CP/M, used on many hobbyist personal computers before Apple and IBM introduced their machines. But Microsoft captured the microcomputer OS market, and with it the market for software applications, with its MS-DOS that came out years later for the IBM PC. For decades, a rumor has persisted that DOS was illegally copied from CP/M and that the fortune accumulated by Bill Gates rightfully belonged to Gary Kildall.
Several years ago, I did a forensic comparison of the binary code for MS-DOS to the source code for CP/M. I could find no signs of copying, and wrote a journal paper and an article about my examination. Since that time, the Computer History Museum in Mountain View, California received the source code for MS-DOS 2.0 from Microsoft and was given permission to make it public. The museum also received the source code for MS-DOS 1.1 from Tim Paterson, the original developer of DOS who was originally contracted by Microsoft to write MS-DOS. Comparing source code is more accurate than comparing binary code, which can produce false negatives, so I decided to perform another comparison to put the question to rest for good.
In addition to source code, I examined whether the DOS commands were copied from CP/M and whether the DOS system calls were copied from CP/M. These issues have also been discussed and debated for decades.
Finally, I will discuss whether DRI could have had a legitimate copyright claim against Microsoft.
on EE Times' sister site, Embedded.