Gary Kildall

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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 mater University of Washington
Occupation Computer scientist
Years active1972–1994
Spouse(s)Dorothy McEwen Kildall
Karen Kildall
Children Scott and Kristen [1]

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.

A computer scientist is a person who has acquired the knowledge of computer science, the study of the theoretical foundations of information and computation and their application.

Microcomputer small, relatively inexpensive computer

A microcomputer is a small, relatively inexpensive computer with a microprocessor as its central processing unit (CPU). It includes a microprocessor, memory, and minimal input/output (I/O) circuitry mounted on a single printed circuit board(PCB). Microcomputers became popular in the 1970s and 1980s with the advent of increasingly powerful microprocessors. The predecessors to these computers, mainframes and minicomputers, were comparatively much larger and more expensive. Many microcomputers are also personal computers.

Entrepreneurship is the process of designing, launching and running a new business, which is often initially a small business. The people who create these businesses are called entrepreneurs.


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 half-Swedish, as Gary's grandmother was born in Långbäck, Sweden, in Skellefteå Municipality, but emigrated to Canada at 23 years of age. [3]

Seattle City in Washington, United States

Seattle is a seaport city on the West Coast of the United States. It is the seat of King County, Washington. With an estimated 744,955 residents as of 2018, Seattle is the largest city in both the state of Washington and the Pacific Northwest region of North America. According to U.S. Census data released in 2018, the Seattle metropolitan area's population stands at 3.94 million, and ranks as the 15th largest in the United States. In July 2013, it was the fastest-growing major city in the United States and remained in the top 5 in May 2015 with an annual growth rate of 2.1%. In July 2016, Seattle was again the fastest-growing major U.S. city, with a 3.1% annual growth rate. Seattle is the northernmost large city in the United States.

Washington (state) State of the United States of America

Washington, officially the State of Washington, is a state in the Pacific Northwest region of the United States. Named for George Washington, the first U.S. president, the state was made out of the western part of the Washington Territory, which was ceded by Britain in 1846 in accordance with the Oregon Treaty in the settlement of the Oregon boundary dispute. The state, which is bordered on the west by the Pacific Ocean, by Oregon to the south, by Idaho to the east, and the Canadian province of British Columbia to the north, was admitted to the Union as the 42nd state in 1889. Olympia is the state capital; the state's largest city is Seattle. Washington is often referred to as Washington State to distinguish it from the nation's capital, Washington, D.C..

Seamanship is the art of operating a ship or boat.

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.

University of Washington Public research university in Seattle, Washington, United States

The University of Washington is a public research university in Seattle, Washington.

Conscription Compulsory enlistment into national or military service

Conscription, sometimes called the draft, is the compulsory enlistment of people in a national service, most often a military service. Conscription dates back to antiquity and continues in some countries to the present day under various names. The modern system of near-universal national conscription for young men dates to the French Revolution in the 1790s, where it became the basis of a very large and powerful military. Most European nations later copied the system in peacetime, so that men at a certain age would serve 1–8 years on active duty and then transfer to the reserve force.

United States Navy Naval warfare branch of the United States Armed Forces

The United States Navy (USN) is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. It is the largest and most capable navy in the world and it has been estimated that in terms of tonnage of its active battle fleet alone, it is larger than the next 13 navies combined, which includes 11 U.S. allies or partner nations. With the highest combined battle fleet tonnage and the world's largest aircraft carrier fleet, with eleven in service, and two new carriers under construction. With 319,421 personnel on active duty and 99,616 in the Ready Reserve, the U.S. Navy is the third largest of the U.S. military service branches in terms of personnel. It has 282 deployable combat vessels and more than 3,700 operational aircraft as of March 2018, making it the third-largest air force in the world, after the United States Air Force and the United States Army.

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]

Doctorate academic or professional degree

A doctorate or doctor's degree or doctoral degree, is an academic degree awarded by universities, derived from the ancient formalism licentia docendi. In most countries, it is a research degree that qualifies the holder to teach at university level in the degree's field, or to work in a specific profession. There are a number of doctoral degrees; the most common is the Doctor of Philosophy (PhD), which is awarded in many different fields, ranging from the humanities to scientific disciplines.

Computer science Study of the theoretical foundations of information and computation

Computer science is the study of processes that interact with data and that can be represented as data in the form of programs. It enables the use of algorithms to manipulate, store, and communicate digital information. A computer scientist studies the theory of computation and the practice of designing software systems.

Computer science is no more about computers than astronomy is about telescopes.

Data-flow analysis is a technique for gathering information about the possible set of values calculated at various points in a computer program. A program's control flow graph (CFG) is used to determine those parts of a program to which a particular value assigned to a variable might propagate. The information gathered is often used by compilers when optimizing a program. A canonical example of a data-flow analysis is reaching definitions.

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]

Digital Research Defunct American software company

Digital Research, Inc. was a company created by Gary Kildall to market and develop his CP/M operating system and related 8-bit, 16-bit and 32-bit systems like MP/M, Concurrent DOS, FlexOS, Multiuser DOS, DOS Plus, DR DOS and GEM. It was the first large software company in the microcomputer world. Digital Research was based in Pacific Grove, California.

IMSAI 8080

The IMSAI 8080 was an early microcomputer released in late 1975, based on the Intel 8080 and later 8085 and S-100 bus. It was a clone of its main competitor, the earlier MITS Altair 8800. The IMSAI is largely regarded as the first "clone" microcomputer. The IMSAI machine ran a highly modified version of the CP/M operating system called IMDOS. It was developed, manufactured and sold by IMS Associates, Inc.. In total, between 17,000 and 20,000 units were produced from 1975 to 1978.

Altair 8800 microcomputer designed in 1975

The Altair 8800 is a microcomputer designed in 1974 by MITS and based on the Intel 8080 CPU. Interest grew quickly after it was featured on the cover of the January 1975 issue of Popular Electronics, and was sold by mail order through advertisements there, in Radio-Electronics, and in other hobbyist magazines. The designers hoped to sell a few hundred build-it-yourself kits to hobbyists, and were surprised when they sold thousands in the first month. The Altair also appealed to individuals and businesses that just wanted a computer and purchased the assembled version. The Altair is widely recognized as the spark that ignited the microcomputer revolution as the first commercially successful personal computer. The computer bus designed for the Altair was to become a de facto standard in the form of the S-100 bus, and the first programming language for the machine was Microsoft's founding product, Altair BASIC.

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.[ citation needed ] 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]

Floppy disk format and density refer to the logical and physical layout of data stored on a floppy disk. Since their introduction, there have been many popular and rare floppy disk types, densities, and formats used in computing, leading to much confusion over their differences. In the early 2000s, most floppy disk types and formats became obsolete, leaving the ​3 12-inch disk, using an IBM PC compatible format of 1440 KB, as the only remaining popular format.

Hard disk drive Data storage device

A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that uses magnetic storage to store and retrieve digital information using one or more rigid rapidly rotating disks (platters) coated with magnetic material. The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces. Data is accessed in a random-access manner, meaning that individual blocks of data can be stored or retrieved in any order and not only sequentially. HDDs are a type of non-volatile storage, retaining stored data even when powered off.

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 into 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,[ citation needed ] 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

Related Research Articles

CP/M Discontinued family of computer operating systems

CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/85-based microcomputers by Gary Kildall of Digital Research, Inc. Initially confined to single-tasking on 8-bit processors and no more than 64 kilobytes of memory, later versions of CP/M added multi-user variations and were migrated to 16-bit processors.

MP/M is a discontinued multi-user version of the CP/M operating system, created by Digital Research developer Tom Rolander in 1979. It allowed multiple users to connect to a single computer, each using a separate terminal.

CP/M-86 Discontinued computer operating system for x86 processors

CP/M-86 was a version of the CP/M operating system that Digital Research (DR) made for the Intel 8086 and Intel 8088. The system commands are the same as in CP/M-80. Executable files used the relocatable .CMD file format. Digital Research also produced a multi-user multitasking operating system compatible with CP/M-86, MP/M-86, which later evolved into Concurrent CP/M-86. When an emulator was added to provide PC DOS compatibility, the system was renamed Concurrent DOS, which later became Multiuser DOS, of which REAL/32 is the latest incarnation. The DOS Plus, FlexOS, and DR DOS families of operating systems started as derivations of Concurrent DOS as well.

86-DOS Discontinued computer operating system for x86 processors and predecessor to MS-DOS/PC DOS

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The history of computing hardware starting at 1960 is marked by the conversion from vacuum tube to solid-state devices such as the transistor and later the integrated circuit. By 1959 discrete transistors were considered sufficiently reliable and economical that they made further vacuum tube computers uncompetitive. Computer main memory slowly moved away from magnetic core memory devices to solid-state static and dynamic semiconductor memory, which greatly reduced the cost, size and power consumption of computers.

The PL/M programming language (an acronym of Programming Language for Microcomputers) is a high-level language conceived and developed by Gary Kildall in 1973 for Hank Smith at Intel for its microprocessors.

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Gordon Eubanks is an American microcomputer industry pioneer who worked with Gary Kildall in the early days of Digital Research (DRI).

IMDOS was a modified version of the CP/M operating system for Intel 8080 processors, used by IMS Associates, Inc. (IMS) for their IMSAI 8080 personal computer. Since MITS would not license their operating system to other manufacturers, IMS approached Gary Kildall and paid a fixed fee of $25,000 for non-exclusive CP/M license.

CBASIC compiled version of the BASIC programming language

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Tom Rolander American computer engineer and entrepreneur, known for MP/M

Thomas Alan Rolander is an American entrepreneur, engineer, and developer of the multitasking multiuser operating system MP/M created for microcomputers in 1979 while working as the first employee of Digital Research with Gary Kildall, the "father" of CP/M. CP/M and MP/M laid the groundwork to later Digital Research operating system families such as Concurrent CP/M, Concurrent DOS and Multiuser DOS. He also developed CP/NET.


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  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. […]
  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.

Further reading