The Road to MS-DOS 2

MS-DOS was an unwanted child. Tim Paterson developed its predecessor 86-DOS only because he urgently needed some kind of operating system for the 8086-based CPU board his employer Seattle Computer Products (SCP) had already released. He really wanted to create a “proper” multitasking system, and knew how to do it, having developed something similar for the Z80 as a school project1. However, the system was needed quickly, so he and his boss agreed to start with something “quick and dirty” that would resemble Digital Research’s CP/M - a minimal operating system developed in 1974 for Intel 8080 based computers with very little memory.Microsoft’s founders Paul Allen and Bill Gates were also getting ready for 16-bit microprocessors. Unsurprisingly, they decided to bet on a system popular on 16-bit minicomputers: UNIX, developed by AT&T’s Bell Labs in the early 1970s and freely distributed to universities. In February 1980, Microsoft licensed UNIX V7 source code from Western Electric…