July 26, 2018

IBM/MS - DOS - Reminiscence


There was not always an MS-DOS from Microsoft, and it wasn’t even dubbed that at birth. The history is worth reviewing now that we in the Multitasking, multi threading, GUI Windows era.

Back in 1980, the ruling PC operating system was DigitalResearch’s CP/M for the z80 processor. Tim Patterson created Quick and Dirty Operating System (QDOS). This was a CP/M clone with a better file system for the processor of the day, the 8086. At the time, no one cared much.


Then, IBM decided to build an 8086-based PC. For this new computer, IBM needed to settle on programming languages and an operating system. It could get the languages from a small independent software vendor called Microsoft, but where could it get an operating system?
The then 25-year-old Bill Gates recommended to go straight to the source: CP/M’s creator and Digital Research founder, Gary Kildall but whether Kildall was really out flying for fun when IBM came by to strike a deal for CP/M for the x86 or not, he didn’t meet with IBM, and they didn’t strike a deal.
So IBM went back to Microsoft and asked it for help in finding an operating system. It just so happened that Paul Allen, Microsoft’s other co-founder, knew about QDOS. Microsoft subsequently bought QDOS for approximately $50,000 in 1981. Then, in short order, IBM made it one of the PC’s operating systems, Microsoft renamed QDOS to MS-DOS, and, crucially, it got IBM to agree that Microsoft could sell MS-DOS to other PC makers. 

That concession was the foundation on which Microsoft would build its empire.

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