In talking to IBM, Bill Gates heard of IBM's predicament for an operating system so he went out and bought one, and hired the guy that created it to turn it into MS DOS. It was one that competed ...

[Yeo Kheng Meng] didn’t cheat by simply running MS-DOS on a modern PC, either: he tested the client on a real 1984 vintage IBM 5155 Portable PC.

This version of 86-DOS is rudimentary even by the standards of early-'80s-era DOS builds and includes just a handful of utilities, a text-based chess game, and documentation for said chess game ...