[asianthrowaway]

You should read up on why Microsoft got the DOS deal. When IBM decided to build their PC, they first sent representatives to visit Microsoft thinking they had an OS in development. However, they didn't at the time, and Gates actually told them to go visit Kildall instead.

When the IBMers arrived at Kildall's house, they got told to wait because Kildall was busy handgliding that day (or something similar). They waited the whole day before deciding they had enough and left.

It's only then that Gates saw an opportunity, and told IBM they could provide an OS.