Gary Kildall (May 19, 1942 - July 11, 1994) was the creator of the CP/M operating system and GEM Desktop graphical user interface, and founder of Digital Research, Inc.

Kildall received his PhD in computer science from the University of Washington in 1972. While working as a professor at the Naval Postgraduate School (NPS) US Navy in Monterey, California, he created implementations of the PL/I programming language for the Intel 4004 and 8008 CPUs. He referred to these versions as PL/M, M for microcomputer.

In 1973, Kildall began work on a disk operating system in order to create a host development environment for PL/M on microcomputers, and ended up with CP/M. He founded Digital Research after his resignation from NPS in 1976 and continued work on CP/M, which he originally sold in classified ads in the back pages of computer magazines. With the release of the Altair 8800 in January 1975 there was a commercial system capable of running CP/M, and before the end of the year a number of clones had appeared with disk drives that required it. By 1977, it was the most popular microcomputer operating system in existence, running on nearly every Intel 8080- and Zilog Z80-based computer.

In 1980, IBM approached Digital Research for a version of CP/M for its upcoming IBM PC. Legend has it that Kildall snubbed the IBM representatives by going flying in his Pitts Special (an aerobatic biplane) for several hours. Although widespread, the story is generally not accepted to be true because it was Kildall's wife, Dorothy, who handled business negotiations, not Kildall himself. Another story has it that IBM representatives wanted Dorothy to sign their standard non-disclosure agreement, which Dorothy considered overly burdensome. IBM returned to talk to Microsoft and Bill Gates saw the business opportunity of a lifetime. He obtained rights to a cloned design of CP/M, QDOS, from Tim Paterson of Seattle Computer products, licensed it to IBM, and MS-DOS/PC-DOS was born.

The possible infringement problems between PC-DOS and CP/M have been the source of much speculation, with secondhand accounts of threatened lawsuits and secret deals, but none of the parties involved ever spoke publicly. Kildall wrote a 226-page memoir shortly before his death in 1994 that contained his account, but the memoir to date has not been published, although it served as source material for a chapter about Kildall and CP/M in the 2004 book They Made America by Harold Evans.

Kildall believed that PC-DOS infringed on CP/M's copyright, but copyright law at is pertained to computer software was in its infancy—the decision in the landmark Apple v. Franklin case was still two years away—and by the accounts of Kildall's employees and friends, Kildall was afraid of engaging IBM in a lengthy and costly lawsuit.

IBM did agree, when the IBM PC was released, to sell the operating system as an unbundled (but necessary) option. One of the operating system options was a new port of CP/M, called CP/M-86, priced at $250. Another option was PC-DOS, priced at $40. Due to the significant price difference, PC-DOS became the primary operating system by default. IBM's decision to source its primary operating system from Microsoft was the beginning of the end of Digital Research's days as the world's largest manufacturer of software for microcomputers.

After CP/M, concerned by the proliferation of BASIC on microcomputers, Kildall created PL/I-80, a ANSI standard subset of the full PL/I programming language, to run on CP/M based microcomputers. He also went on to create a variety of experimental projects, including an implementation of the Logo educational programming language and interfaces between computers and CD-ROM drives and videodisc players. He created a CD-ROM version of Grolier's Encyclopedia. He left Digital Research in 1991 when the company was sold to Novell, and moved to suburban Austin, Texas, keeping a second home in California. Friends and acquaintances reported he was bitter at how MS-DOS, whose design was almost entirely based on his own ideas in creating CP/M, made Bill Gates and Microsoft famous while he languished in obscurity.

He died in 1994 of uncertain causes in Monterey, California at the age of 52. Some reports suggest Kildall suffered a fall at the Franklin Street Bar and Grill in Monterey on July 8 and died of internal bleeding three days later.

In March 1995, Kildall was posthumously honored by the Software Publishers Association for his contributions to the computer industry:

• Introduction of operating systems with preemptive multitasking and windowing capabilities and menu-driven user interfaces.
• Creation of the first diskette track buffering schemes, read-ahead algorithms, file directory caches, and RAM disk emulators.
• Introduction of a binary recompiler in the 1980s.
• The first programming language and first compiler specifically for microprocessors.
• The first microprocessor disk operating system, which eventually sold a quarter million copies.
• The first computer interface for video disks to allow automatic nonlinear playback, presaging today's interactive multimedia.
• The file system and data structures for the first consumer CD-ROM.
• The first successful open-system architecture by segregating system-specific hardware interfaces in a set of BIOS routines, making the whole third-party software industry possible.

External links

• http://www.maxframe.com/DR.HTM
• Category at ODP http://dmoz.org/Computers/History/Pioneers/Kildall,_Gary/
• 2004 Businessweek story about Kildall http://www.businessweek.com/magazine/content/04_43/b3905109_mz063.htm