Gary Kildall

Gary Arlen Kildall (/ˈkɪldˌɔːl/; May 19, 1942 – July 11, 1994) was an American computer scientist and microcomputer entrepreneur who created the CP/M operating system and founded Digital Research, Inc. (DRI). Kildall was one of the first people to see microprocessors as fully capable computers, rather than equipment controllers, and to organize a company around this concept.[2] He also co-hosted the PBS TV show The Computer Chronicles. Although his career in computing spanned more than two decades, he is mainly remembered in connection with IBM's unsuccessful attempt in 1980 to license CP/M for the IBM Personal Computer.

Gary Kildall
Gary Kildall at the European Development Centre in Hungerford, United Kingdom, 1988.
Born(1942-05-19)May 19, 1942
DiedJuly 11, 1994(1994-07-11) (aged 52)
Alma materUniversity of Washington
OccupationComputer scientist
Years active1972–1994
Spouse(s)Dorothy McEwen Kildall
Karen Kildall
ChildrenScott and Kristen[1]

Early life

Gary Kildall was born and grew up in Seattle, Washington, where his family operated a seamanship school. His father, Joseph Kildall, was a captain of Norwegian heritage. His mother Emma was of half Swedish descent, as Gary's grandmother was born in Långbäck, Sweden, in Skellefteå Municipality, but emigrated to Canada at 23 years of age.[3]

Gary attended the University of Washington (UW) hoping to become a mathematics teacher, but became increasingly interested in computer technology. After receiving his degree,[4] he fulfilled a draft obligation to the United States Navy by teaching at the Naval Postgraduate School (NPS) in Monterey, California.[5] Being within an hour's drive of Silicon Valley, Kildall heard about the first commercially available microprocessor, the Intel 4004. He bought one of the processors and began writing experimental programs for it. To learn more about the processors, he worked at Intel as a consultant on his days off.

Kildall briefly returned to UW and finished his doctorate in computer science in 1972,[6] then resumed teaching at NPS. He published a paper that introduced the theory of data-flow analysis used today in optimizing compilers,[7] and he continued to experiment with microcomputers and the emerging technology of floppy disks. Intel lent him systems using the 8008 and 8080 processors, and in 1973, he developed the first high-level programming language for microprocessors, called PL/M.[5] He created CP/M the same year to enable the 8080 to control a floppy drive, combining for the first time all the essential components of a computer at the microcomputer scale. He demonstrated CP/M to Intel, but Intel had little interest and chose to market PL/M instead.[5]

Business career


Kildall and his wife Dorothy established a company, originally called "Intergalactic Digital Research" (later renamed as Digital Research, Inc), to market CP/M through advertisements in hobbyist magazines. Digital Research licensed CP/M for the IMSAI 8080, a popular clone of the Altair 8800. As more manufacturers licensed CP/M, it became a de facto standard and had to support an increasing number of hardware variations. In response, Kildall pioneered the concept of a BIOS, a set of simple programs stored in the computer hardware (ROM or EPROM chip) that enabled CP/M to run on different systems without modification.[5]

CP/M's quick success took Kildall by surprise, and he was slow to update it for high density floppy disks and hard disk drives. After hardware manufacturers talked about creating a rival operating system, Kildall started a rush project to develop CP/M 2.[8] By 1981, at the peak of its popularity, CP/M ran on 3,000 different computer models and DRI had $5.4 million in yearly revenues.[5]

IBM dealings

IBM, presided by John R. Opel, approached Digital Research in 1980, at Bill Gates' suggestion,[9] to negotiate the purchase of a forthcoming version of CP/M called CP/M-86 for the IBM PC. Gary had left negotiations to his wife, Dorothy, as he usually did, while he and colleague and developer of MP/M operating system Tom Rolander used Gary's private airplane to deliver software to manufacturer Bill Godbout.[2][10] Before the IBM representatives would explain the purpose of their visit, they insisted that Dorothy sign a non-disclosure agreement. On the advice of DRI attorney Gerry Davis, Dorothy refused to sign the agreement without Gary's approval. Gary returned in the afternoon and tried to move the discussion with IBM forward, but accounts disagree on whether he signed the non-disclosure agreement, as well as if he ever met with the IBM representatives.[11]

Various reasons have been given for the two companies failing to reach an agreement. DRI, which had only a few products, might have been unwilling to sell its main product to IBM for a one-time payment rather than its usual royalty-based plan.[12] Dorothy might have believed that the company could not deliver CP/M-86 on IBM's proposed schedule, as the company was busy developing an implementation of the PL/I programming language for Data General.[13] Also possible, the IBM representatives might have been annoyed that DRI had spent hours on what they considered a routine formality.[10] According to Kildall, the IBM representatives took the same flight to Florida that night that he and Dorothy took for their vacation, and they negotiated further on the flight, reaching a handshake agreement. IBM lead negotiator Jack Sams insisted that he never met Gary, and one IBM colleague has confirmed that Sams said so at the time. He accepted that someone else in his group might have been on the same flight, but noted that he flew back to Seattle to talk with Microsoft again.[10]

Sams related the story to Gates, who had already agreed to provide a BASIC interpreter and several other programs for the PC. Gates' impression of the story was that Gary capriciously "went flying", as he would later tell reporters.[14] Sams left Gates with the task of finding a usable operating system, and a few weeks later he proposed using the operating system 86-DOS—an independently developed operating system that implemented Kildall's CP/M API—from Seattle Computer Products (SCP). Paul Allen negotiated a licensing deal with SCP. Allen had 86-DOS adapted for IBM's hardware, and IBM shipped it as IBM PC DOS.[11]

Kildall obtained a copy of PC DOS, examined it, and concluded that it infringed on CP/M. When he asked Gerry Davis what legal options were available, Davis told him that intellectual property law for software was not clear enough to sue.[15] Instead Kildall only threatened IBM with legal action, and IBM responded with a proposal to offer CP/M-86 as an option for the PC in return for a release of liability.[16] Kildall accepted, believing that IBM's new system (like its previous personal computers) would not be a significant commercial success.[17] When the IBM PC was introduced, IBM sold its operating system as an unbundled option. One of the operating system options was PC DOS, priced at US$40. PC DOS was seen as a practically necessary option; most software titles required it and without it the IBM PC was limited to its built-in Cassette BASIC. CP/M-86 shipped a few months later six times more expensive at $240, but sold poorly against DOS and enjoyed far less software support.[2]

Later work

With the loss of the IBM deal, Gary and Dorothy found themselves under pressure to bring in more experienced management, and Gary's influence over the company waned. He worked in various experimental and research projects, such as a version of CP/M with multitasking (MP/M) and an implementation of the Logo programming language.[5] He hoped that Logo, an educational dialect of LISP, would supplant BASIC in education, but it did not.[18] After seeing a demonstration of the Apple Lisa, Kildall oversaw the creation of DRI's own graphical user interface, called GEM. Novell acquired DRI in 1991 in a deal that netted millions for Kildall.[15]

Kildall also pursued computing-related projects outside DRI. During the seven years from 1983 to 1990 he co-hosted a public television program on the side, called Computer Chronicles, that followed trends in personal computing. In 1984 he started another company, Activenture, which adapted optical disc technology for computer use.[19] In early 1985 it was renamed KnowledgeSet and released the first computer encyclopedia in June 1985, a CD-ROM version of Grolier's Academic American Encyclopedia[11][19][13] named The Electronic Encyclopedia,[20] later acquired by Banta Corporation.[21] Kildall's final business venture, known as Prometheus Light and Sound (PLS) and based in Austin, Texas, developed a home PBX system[5] that integrated land-line telephones with mobile phones.

Personal life

Kildall's colleagues recall him as creative, easygoing, and adventurous. In addition to flying, he loved sports cars, auto racing, and boating, and he had a lifelong love of the sea.[2][5]

Although Kildall preferred to leave the IBM affair in the past and to be known for his work before and afterward, he continually faced comparisons between himself and Bill Gates, as well as fading memories of his contributions. A legend grew around the fateful IBM-DRI meeting, encouraged by Gates and various journalists, suggesting that Kildall had irresponsibly taken the day off for a recreational flight, and he became tired of constantly having to refute that story.[13] In later years, he had occasional private expressions of bitterness at being overshadowed by Microsoft.[5]

Kildall was annoyed when the University of Washington asked him, as a distinguished graduate, to attend their computer science program anniversary in 1992, but gave the keynote speech to Gates, a dropout from Harvard. In response, he started writing his memoir, Computer Connections.[15] The memoir,[22][23][24] which he distributed only to a few friends, expressed his frustration that people did not seem to value elegance in software,[18] and it said of Gates, "He is divisive. He is manipulative. He is a user. He has taken much from me and the industry." In an appendix he called DOS "plain and simple theft" because its first 26 system calls worked the same as CP/M's.[25] He accused IBM of contriving the price difference between PC DOS and CP/M-86 in order to marginalize CP/M. The journalist Harold Evans used the memoir as a source for a chapter about Kildall in the 2004 book They Made America, concluding that Microsoft had robbed Kildall of his inventions.[13] IBM veterans from the PC project disputed the book's description of events, and Microsoft described it as "one-sided and inaccurate".[15] In August 2016, Kildall's family made the first part of his memoir available to the public.[23][22][24]

Selling DRI to Novell had made Kildall a wealthy man, and he moved to the West Lake Hills suburb of Austin. His Austin house was a lakeside property, with stalls for several sports cars, plus a video studio in the basement. Kildall owned and flew his own Learjet and had at least one boat on the lake. While in Austin he also participated in volunteer efforts to assist children with HIV/AIDS. He owned a mansion with a panoramic ocean view in Pebble Beach, California, near the headquarters of DRI.


On July 8, 1994, Kildall fell at a Monterey, California, biker bar and hit his head.[26] The exact circumstances of the injury remain unclear. He had been an alcoholic in his later years.[15][27] Various sources have claimed he fell from a chair, fell down steps, or was assaulted, because he had walked into the Franklin Street Bar & Grill wearing Harley-Davidson leathers.[12] He checked in and out of the hospital twice, and died three days later at the Community Hospital of the Monterey Peninsula. An autopsy the next day did not conclusively determine a cause of death.[25][1] A CP/M Usenet FAQ says he was concussed from the fall and died of a heart attack; the connection between the two are unclear.[28] He is buried in Evergreen Washelli Memorial Park in north Seattle.


Following the announcement of Kildall's death, Bill Gates commented that he was "one of the original pioneers of the PC revolution" and "a very creative computer scientist who did excellent work. Although we were competitors, I always had tremendous respect for his contributions to the PC industry. His untimely death was very unfortunate and his work will be missed."[2]

In March 1995, Kildall was posthumously honored by the Software Publishers Association (now the Software and Information Industry Association) for his contributions to the microcomputer industry:[5][29]

In April 2014, the city of Pacific Grove installed a commemorative plaque outside Kildall's former residence, which also served as the early headquarters of Digital Research.[35]

See also


  1. Markoff, John (1994-07-13). "Gary Kildall, 52, Crucial Player In Computer Development, Dies". The New York Times. p. D19.
  2. "Special Edition: Gary Kildall". The Computer Chronicles. 1995. Archived from the original on 2014-07-02. Retrieved 2014-06-13.
  3. Andersson, Ulrika (2009-01-19). "Skellefteåättling kunde ha varit Bill Gates". Norra Västerbotten (in Swedish). Archived from the original on 2009-05-24. Retrieved 2009-05-07.
  4. Kildall, Gary Arlen (December 1968). Experiments in large-scale computer direct access storage manipulation (M.Sc. thesis). University of Washington. Thesis No. 17341.
  5. Swaine, Michael (1997-04-01). "Gary Kildall and Collegial Entrepreneurship". Dr. Dobb's Journal. Archived from the original on 2007-01-24. Retrieved 2006-11-20.
  6. Kildall, Gary Arlen (May 1972). Global expression optimization during compilation (Ph.D. dissertation). Seattle, Washington, USA: University of Washington, Computer Science Group. Thesis No. 20506, Technical Report No. 72-06-02.
  7. Kildall, Gary Arlen (1973-10-01). "A Unified Approach to Global Program Optimization" (PDF). Proceedings of the 1st Annual ACM SIGACT-SIGPLAN Symposium on Principles of Programming Languages (POPL). Boston, Massachusetts, USA: 194–206. doi:10.1145/512927.512945. hdl:10945/42162. Archived (PDF) from the original on 2017-06-29. Retrieved 2006-11-20. ()
  8. Eubanks, Gordon. Akass, Clive (ed.). "Interview: Gordon Eubanks, Former Student & CEO of Oblix, Inc". Recollections of Gary Kildall (Interview). Archived from the original on 2006-12-09. Retrieved 2006-11-30.
  9. Isaacson, Walter (2014). The Innovators: How a Group of Inventors, Hackers, Geniuses, and Geeks Created the Digital Revolution. Simon & Schuster. p. 358. ISBN 978-1476708690.
  10. Wallace, James; Erickson, Jim (1993). Hard Drive: Bill Gates and the Making of the Microsoft Empire. New York: HarperBusiness. ISBN 0-88730-629-2. ISBN 978-0-88730-629-7.
  11. Freiberger, Paul; Swaine, Michael (2000) [1984]. Fire in the Valley: The Making of the Personal Computer (2nd ed.). New York, N.Y., USA: McGraw-Hill. ISBN 0-07-135892-7. ISBN 978-0-07-135892-7.
  12. Young, Jeffrey (1997-07-07). "Gary Kildall: The DOS That Wasn't". Forbes. Archived from the original on 2011-06-23. Retrieved 2011-08-29.
  13. Evans, Harold; Buckland, Gail; Lefer, David (2004). They Made America: From the Steam Engine to the Search Engine: Two Centuries of Innovators. Little, Brown and Company. ISBN 978-0-316-27766-2. ISBN 0-316-27766-5.
  14. Manes, Stephen; Andrews, Paul (1992). Gates: How Microsoft's Mogul Reinvented an Industry—and Made Himself the Richest Man in America. Doubleday. ISBN 0-671-88074-8. ISBN 978-0-671-88074-3.
  15. Hamm, Steve; Greene, Jay (2004-10-25). "The Man Who Could Have Been Bill Gates - A new book says Gates got the rewards due Gary Kildall. What's the real story?". BusinessWeek. Bloomberg Businessweek. Archived from the original on 2012-06-29. Retrieved 2006-11-13.
  16. Eubanks, Gordon (2000-11-08). Morrow, Daniel S. (ed.). "Gordon Eubanks Oral History" (PDF). Computerworld Honors Program International Archives (Interview). Cupertino, CA, USA. Archived from the original (PDF) on 2009-03-26. Retrieved 2006-11-20.
  17. Rolander, Tom (2007-08-08). Scoble, Robert (ed.). "Scoble Show". (Interview). Archived from the original on 2016-11-11. Retrieved 2016-11-11.
  18. Rolander, Tom (1994-07-15). "In Memory of GARY A. KILDALL May 19, 1942 -- July 11, 1994". Tom Rolander's Website and Album (Memorial service). Naval Postgraduate School, Monterey, Calif., USA. Archived from the original on 2007-09-27. Retrieved 2006-11-30.
  19. Allan, Roy A. (2001). A History of the Personal Computer - The People and the Technology (ebook) (1 ed.). Allan Publishing. ISBN 0-9689108-3-1. ISBN 978-0-9689108-3-2. Retrieved 2016-11-18.
  20. Stark, Craig L. (1986-04-29). "CD ROM Conference: Lured by 600 Megabytes on Disk". PC Magazine: 42. Retrieved 2016-11-19.
  21. "Tom Rolander - Serial entrepreneur and Emergent Farming co-founder". Retrieved 2016-11-11.
  22. Shustek, Len (2016-08-02). "In His Own Words: Gary Kildall". Remarkable People. Computer History Museum. Archived from the original on 2016-12-17. Retrieved 2016-11-17.
  23. Perry, Tekla S. (2016-08-03). "CP/M Creator Gary Kildall's Memoirs Released as Free Download". IEEE Spectrum. Archived from the original on 2016-11-17. Retrieved 2016-11-17. Later chapters, they indicated, did "not reflect his true self," but rather his struggles with alcoholism, and will remain unpublished.
  24. Kildall, Gary Arlen (2016-08-02) [1993]. Kildall, Scott; Kildall, Kristin (eds.). "Computer Connections: People, Places, and Events in the Evolution of the Personal Computer Industry" (Manuscript, part 1). Kildall Family. Archived from the original on 2016-11-17. Retrieved 2016-11-17. Cite journal requires |journal= (help)
  25. Andrews, Paul (1994-07-14). "A Career Spent in Gates' Shadow—Computer Pioneer Dies at 52". The Seattle Times. Archived from the original on 2017-10-13. Retrieved 2017-04-29.
  26. Akass, Clive (2006-08-11). "The man who gave Bill Gates the world - Gary Kildall was one of the founding fathers of the PC but he is remembered now for his greatest mistake". Personal Computer World. Archived from the original on 2008-10-11.
  27. Rivlin, Gary (1999). The Plot to Get Bill Gates. Crown Business. ISBN 978-0-8129-3006-1. ISBN 0-8129-3006-1.
  28. Kirkpatrick, Don (1999-01-12). "comp.os.cpm Frequently Asked Questions (FAQ)". Archived from the original on 2007-09-29. Retrieved 2006-11-20.
  29. Wharton, John (1994-08-01). "Gary Kildall, industry pioneer, dead at 52: created first microcomputer languages, disk operating systems". Microprocessor Report (PDF). MicroDesign Resources Inc. (MDR). 8 (10). Archived from the original on 2016-11-18. Retrieved 2016-11-18.
  30. Kildall, Gary Arlen (June 1975), CP/M 1.1 or 1.2 BIOS and BDOS for Lawrence Livermore Laboratories, An excerpt of the BDOS.PLM file header in the PL/M source code of CP/M 1.1 or CP/M 1.2 for Lawrence Livermore Laboratories (LLL):
    /* C P / M   B A S I C   I / O    S Y S T E M    (B I O S)
                        COPYRIGHT (C) GARY A. KILDALL
                                 JUNE, 1975                   */
    /*  B A S I C   D I S K    O P E R A T I N G   S Y S T E M  (B D O S)
                        COPYRIGHT (C) GARY A. KILDALL
                                JUNE, 1975                          */
  31. Kildall, Gary Arlen (January 1980). "The History of CP/M, The Evolution of an Industry: One Person's Viewpoint". 5 (1). Dr. Dobb's Journal of Computer Calisthenics & Orthodontia: 6–7. Archived from the original on 2016-11-24. Retrieved 2013-06-03. […] The first commercial licensing of CP/M took place in 1975 with contracts between Digital Systems and Omron of America for use in their intelligent terminal, and with Lawrence Livermore Laboratories where CP/M was used to monitor programs in the Octopus network. Little attention was paid to CP/M for about a year. In my spare time, I worked to improve overall facilities […] By this time, CP/M had been adapted for four different controllers. […] In 1976, Glenn Ewing approached me with a problem: Imsai, Incorporated, for whom Glenn consulted, had shipped a large number of disk subsystems with a promise that an operating system would follow. I was somewhat reluctant to adapt CP/M to yet another controller, and thus the notion of a separated Basic I/O System (BIOS) evolved. In principle, the hardware dependent portions of CP/M were concentrated in the BIOS, thus allowing Glenn, or anyone else, to adapt CP/M to the Imsai equipment. Imsai was subsequently licensed to distribute CP/M version 1.3, which eventually evolved into an operating system called IMDOS. […] Cite journal requires |journal= (help)
  32. Killian, A. Joseph "Joe" (2001). "Gary Kildall's CP/M: Some early CP/M history - 1976-1977". Thomas "Todd" Fischer, IMSAI. Archived from the original on 2012-12-29. Retrieved 2013-06-03. […] When we failed to produce an operating system in a timely manner, Glenn started talking with Gary about CPM […] It took several months of twisting Gary's arm to get Gary to port it to the 8080. The final success came when Glenn talked Gary into just separating the I/O from the rest of it, with Glenn promising to re-write the I/O module for the IMSAI 8080 (which he did). So CPM on the IMSAI was a joint effort between Glenn and Gary. […]
  33. Fraley, Bob; Spicer, Dag (2007-01-26). "Oral History of Joseph Killian, Interviewed by: Bob Fraley, Edited by: Dag Spicer, Recorded: January 26, 2007, Mountain View, California, CHM Reference number: X3879.2007" (PDF). Computer History Museum. Archived (PDF) from the original on 2014-07-14. Retrieved 2013-06-03. Killian: "[…] Intel had hired him a few months earlier to write a control program monitor to run on their little demo system for 8008 and now 8080. […] Glenn knew this and he would be talking with Gary, and he started twisting Gary's arm. He said, "Hey Gary, why can't we run this in this IMSAI?" "The I/O's all different, won't run." But Glenn persists and finally makes a deal with Gary. He says, "Okay Gary, if you split out the I/O, I'll write the BIOS, basic I/O's system," and Glenn named it then. "We'll split it out separately. I'll write that part, as long as you can make a division in the program there." And he got Gary to do that and Glenn put those two pieces together and was running Gary's CP/M on an IMSAI. Glenn let us know that, and it wasn't too much later than Bill was down there making arrangements with Gary Kildall to license CP/M. […] Now that the BIOS is separated out, anybody could write a BIOS for their machine, if it was 8080-based, and run this, so he started selling that separately under the company Digital Research that he formed and did quite well."
  34. Digital Research (1981). XLT86 - 8080 to 8086 Assembly Language Translator - User's Guide (PDF). Pacific Grove, Calif., USA: Digital Research, Inc. Archived (PDF) from the original on 2016-11-18. Retrieved 2016-11-18.
  35. Sammon, John (2014-04-27). "Computer pioneer honored in Pacific Grove". The Monterey County Herald. Archived from the original on 2014-05-08.

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