Tim+Paterson

Most of Microsoft's revenues in the 1980s and early 1990s came from its MS-DOS (disk operating system), which was originally developed by Tim Paterson as a "quick and dirty operating system" for personal computers running on the 8086 Intel processor. Microsoft the software from Paterson for exclusive rights for the cost of $75,000. Microsoft proceeded to earn billions in revenues from its software offerings used in IBM PCs.

From Wikipedia:

"**Tim Paterson** (born 1956) is an [|American] [|computer programmer], best known as the original author of [|MS-DOS], the most widely used personal computer [|operating system] in the 1980s. Paterson was educated in the Seattle Public Schools, graduating from [|Ingraham High School] in 1974. He attended the [|University of Washington], working as a repair [|technician] for The Retail Computer Store in the Green Lake area of [|Seattle, Washington], and graduated //[|magna cum laude]// with a degree in Computer Science in June 1978. He went to work for [|Seattle Computer Products] as a designer and engineer. He designed a schematic of Microsoft's [|Z-80 SoftCard] which had a Z80 CPU and ran the [|CP/M] operating system on an Apple II.

A month later, Intel released the [|8086] CPU, and Paterson went to work designing an [|S-100] 8086 board, which went to market in November 1979. The only commercial software that existed for the board was a standalone version of [|Microsoft BASIC]. The standard CP/M operating system at the time was not available for this CPU and without a true operating system, sales were slow. Paterson began work on QDOS (Quick and Dirty Operating System) in April 1980 to fill that void, copying the [|APIs] of CP/M from sources including the published CP/M manual so that it would be highly compatible. QDOS was soon renamed as [|86-DOS]. Version 0.10 was complete by July 1980. By version 1.14 86-DOS had grown to 4,000 lines of assembly code.[|[][|1][|]] In December 1980 [|Microsoft] secured the rights to market 86-DOS to other hardware manufacturers."