So who really wrote MS-DOS?

A new twist on an old story. The pivot is that Microsoft’s fortunes were originally founded on MS-DOS, the operating system the company produced for the IBM PC and its clones in 1981. The irony is that when IBM came calling to buy an operating system, Microsoft didn’t have one, but Bill Gates went round the corner to Seattle Computer Products, which had written a DOS for the Intel 8086 chip that was to power the new PC, and bought it outright for a piffling sum (I think it was $50k). It was called Seattle Computing Products DOS. One of the great stories in the industry is that the IBM guys had called first at Digital research, Gary Kildall’s company in California, which had produced the first real microcomputer operating system (CP/M) to see if he was interested in developing a 16-bit version for the PC. But when the suits called, Kildall was out flying his plane and his wife (who answered the door) refused to sign the Non Disclosure Agreement that the IBM guys insisted on before they would open the conversation.

So we have two ironies: 1. How Kildall missed the chance to hit the big time; and 2. How the brass-necked Gates, who didn’t have an operating system, acquired one double-quick and sold it to IBM while retaining the right to sell it to other computer manfacturers.

But there is a third strand, which is the question of how Seattle Computer Products DOS came to be written. In his book, They made America, Harry Evans told the story about Kildall and Gates and the Seattle DOS which he described as a “slapdash clone” and “rip-off” of Kildall’s CP/M operating system. Now Tim Paterson, the software’s main author, has sued Evans and his publisher (Random House) for defamation. Evans says he will vigorously contest the case. Stand by for the public laundering of some very interesting dirty linen.