My (first) KAYPRO-II seen from the front.

This Z80 2 Mhz system was running the famous CP/M operating system, developed in 1973 (!!!) by Dr. Gary Kildall, of Digital Research Inc. (DRI).

Kildall was the inventor of a programming language called: PLM, He implemented it on the 8080 Intel Microprocessor, and created a (character based) Operating System, called: CP/M, the first personal computer operating system for microcomputers, and at that time because the standard OS for many microcomputers, like Kaypro, Osborne, Superbrain etc.

Horror story:

In a chapter devoted to Kildall in Evans' 'They Made America: From the Steam Engine to the Search Engine: Two Centuries of Innovators', Evans related how Paterson "[took] 'a ride on' Kildall's operating system, appropriated the 'look and feel' of [Kildall's] CP/M operating system, and copied much of his operating system interface from CP/M."

The story of how Bill Gates came to acquire an operating system is well known. In 1980, Kildall's Digital Research provided the operating system for a wide range of microcomputers, and was established as the industry standard. IBM had approached Microsoft, then a tiny software company in the Seattle area, to provide a BASIC run-time for its first micro, the IBM PC. Gates 'smelled' BIG business: He offered to provide IBM an operating system too, even though he didn't have one at the time. This required a hasty purchase.

Microsoft turned to Tim Paterson, whose garage operation 'Seattle Computer Products' (SCP) was selling a CP/M clone called 86-DOS. This had been developed under the code name QDOS (for "quick and dirty operating system"), and SCP sold it alongside an add-in CPU card. Microsoft turned this into the hugely successful DOS franchise.

(The oft-told story of Kildall spurning IBM to fly his plane is deeply misleading. It was IBM's distribution and OVERpricing of CP/M (6 fold the price of MS-DOS: (IBM offered PC-DOS (Microsoft) for 40 US$ and CP/M-86 for 240 US$, so obviously DRI lost the battle and Bill won the marketshare, and the rest is history!!), which in the end was one of three operating systems offered with the first IBM PC, that ensured MS-DOS captured the market.)

Later, Kildall created GEM, the FIRST graphical operating system. even before Apple did that!!!

Here's some info on CP/M:

http://en.wikipedia.org/wiki/CP/M

http://www.retrotechnology.com/dri/d_dri_refs.html

And here;s a 3 part Youtube video on Gary Kildall:
part 1: http://www.youtube.com/watch?v=VipwFeJ1KMU
part 2: http://www.youtube.com/watch?v=pkxksoOqk-U&feature=related
part 3: http://www.youtube.com/watch?v=rqfwIvjDlAA&feature=related