Gary Arlen Kildall (born 1942)

Born May 19, 1942 in Seattle, Washington, U.S. ( [HK0037][GDrive] )

Died July 11, 1994 (aged 52) Monterey, California, U.S. ( [HK0037][GDrive] )

Also see :

Associated with :

Computer Chronicles : Gary Kildall tribute video (1995)

Saved copy : [HV00CJ][GDrive]

Saved Wikipedia (Oct 13, 2020) - Gary Kildall

See : [HK0037][GDrive]

Alma mater University of Washington (BS, MS, PhD)[1][2]



Dorothy McEwen Kildall

Karen Kildall


Scott and Kristen[3]

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.[4] He also co-hosted the PBS TV show Computer Chronicles. Although his career in computing spanned more than two decades, he is mainly remembered in connection with his development of the CP/M operating system, an early multi-platform microcomputer OS that has many parallels to the later MS-DOS used on the IBM PC.

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.[5]

Gary attended the University of Washington (UW) hoping to become a mathematics teacher, but became increasingly interested in computer technology. After receiving his degree,[1] he fulfilled a draft obligation to the United States Navy by teaching at the Naval Postgraduate School (NPS) in Monterey, California.[6] 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,[2] then resumed teaching at NPS. He published a paper that introduced the theory of data-flow analysis used today in optimizing compilers[7] (sometimes known as Kildall's method), 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.[6] For Intel he also wrote an 8080 instruction set simulator named INTERP/80. 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.[6]

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.[6]

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 3000 different computer models and DRI had US$5.4 million in yearly revenues.[6]

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.[4][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 US$240, but sold poorly against DOS and enjoyed far less software support.[4]

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.[6] 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 resigned as CEO of Digital Research on 28 June 1985, but remained chairman of the board.[19]

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.[20] 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][20][13] named The Electronic Encyclopedia,[21] later acquired by Banta Corporation.[22] Kildall's final business venture, known as Prometheus Light and Sound (PLS) and based in Austin, Texas, developed a home PBX system[6] 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.[4][6]

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.[6]

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,[23][24][25] 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.[26] 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.[24][23][25]

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, and 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.[27] The exact circumstances of the injury remain unclear. He had been an alcoholic in his later years.[15][28] 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.[26][3] 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.[29] 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."[4]

In March 1995, Kildall was posthumously honored by the Software Publishers Association (SPA) for his contributions to the microcomputer industry:[30][31][6]



^ 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)


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)


JUNE, 1975 */

Further reading

External links

Wikiquote has quotations related to: Gary Kildall

1973 (or 1974) - Resume for Gary Kildall

Source (PDF) : [HL005D][GDrive]

Gary A. Kildall was born in Seattle, Washington, on 19 May 1942. He attended the University of Washington in Seattle where he majored in mathematics. He received the degree of Bachelor of Science in June 1967.

He attended Officer Candidate School in Newport, Rhode Island, and was commissioned in August 1967. He received a delay in reporting for active duty to pursue graduate study.

Remaining at the University of Washington, he did research in areas of computer science, including artificial intelligence, information retrieval, compiler design, and operating systems design. He received the degree of Master of Science in Computer Science in December 1968.

In January 1969 he reported for active duty at the Naval Postgraduate School, Monterey, California, where he taught in the Department of Mathematics.

Upon release from active duty in January 1972 he returned to the University of Washington where he received the degree of Doctor of Philosophy in June 1972. His research in the area of compiler code optimization was under the direction of Professor Hellmut Golde [See Hellmut Paul Oscar Golde (born 1930) ] .

In March 1972 he joined the faculty of the Mathematics Department of the Naval Postgraduate School, Monterey, California.

He is presently teaching in the Computer Science Group. His current research is in micro-computer organization and applications.

He is a member of the Association for Computing Machinery.



Books, published papers, notes, letters

  1. 1ALGOL-E: An Experimental Approach to the Study of Progranming IP Languages with A. Roberts

    • 2nd Symposium on Education in Computer Science, Washington Univ., St. Louis, March 24, 1972

    • SIGCSE Bull., 4(1), 127-135 (1972}

  2. A Unified Approach to Global Program Optimization IP

    • ACM Symposium on Principles of Prograrrrning Languages, Oct. 1973

    • Proc., 194-206 (l973)

2020 (OCT 12) - Evidence that "Gary Kildall" has been intentionally wiped from Newspapers-dot-com site


1994 (July 13) - "Gary Kildall, 52, Crucial Player In Computer Development, Dies"

Source : [HN019T][GDrive]

Gary Kildall, a pioneering computer scientist who created the first popular operating system for personal computers, died on Monday at the Community Hospital of the Monterey Peninsula in Monterey, Calif. He was 52.

An autopsy performed yesterday failed to determine the cause of death, said John DiCarlo, Monterey County's deputy coroner.

While teaching computer science at the United States Naval Postgraduate School in Monterey in 1973, Mr. Kildall wrote a personal computer operating system, a fundamental program that controlled the way the central processing unit stored and retrieved information from a floppy disk drive. He named the program Control Program/Monitor, or CP/M.

Before his program was available, inexpensive hobbyist microcomputers were generally programmed with a punched paper tape reader or by laboriously entering information by setting combinations of on-off switches to encode each byte. Founding Digital Research

With his wife, Dorothy McEwen, Mr. Kildall founded a company to sell the CP/M operating system from their home in 1974. At first they called the company Intergalactic Digital Research, but the name was quickly shortened to Digital Research.

In 1977 Digital Research licensed CP/M to IMSAI, one of the early makers of personal computers. In the years afterward the program became the standard operating system for the first generation of 8-bit microcomputers.

Even before the invention of the electronic spreadsheet, these machines quickly became useful for business applications like word processing and relational databases, and by the early 1980's Digital Research's yearly revenues were $5 million.

Despite his business success, Mr. Kildall stayed on for several years as a professor at the Naval Postgraduate School because he enjoyed teaching. Meeting With I.B.M.

In one of the most controversial events in the history of personal computing, Mr. Kildall was approached by I.B.M. in 1980 to develop a 16-bit version of CP/M for its new personal computer.

There is a legend in the computer industry that Mr. Kildall ignored the I.B.M. representatives who had arrived for a meeting and went flying in his airplane instead. But Mr. Kildall has said that in fact he attended the meeting and left believing that he had struck a deal with I.B.M.

In any case, I.B.M. executives later met with a small software company, the Microsoft Corporation, then located in Bellevue, Wash., founded by William Gates to sell his version of the BASIC computer language. Upon learning that I.B.M. was designing a personal computer, Mr. Gates, who at the time did not sell an operating system, rushed to buy one from a small Seattle company.

Eventually I.B.M. offered both Digital Research's CP/M-16 and Microsoft's MS-DOS operating systems with the I.B.M. PC. But it priced its version of the Microsoft operating system, PC-DOS, at $40 and the Digital Resarch operating system at $240.

PC-DOS quickly became the standard operating system for the I.B.M. PC, and when Compaq produced the first I.B.M.-compatible personal computer, MS-DOS became the industry standard. Microsoft eventually became the leading supplier of all kinds of personal computer software, and eventually broke with I.B.M. in a dispute over MS-DOS's successor operating system, OS2.

Many people in the computer industry argued that Microsoft's MS-DOS infringed on CP/M patents, but Mr. Kildall decided not to sue.

"In those days everyone was imitating everyone else," he said in a magazine interview several years ago. "That's why I didn't do anything about CP/M; it never occurred to me."

Mr. Kildall was widely viewed as a creative innovator in software design who disliked the cut-throat aspects of business and avoided many of the more aggressive tactics employed by his competitors in the computer industry.

Thomas Rolander, who was director of engineering for Digital Research when the company was approached by I.B.M., said he had flown with Mr. Kildall on the day of the I.B.M. meeting. He said he and Mr. Kildall arrived late at the meeting and refused to sign a nondisclosure document from the computer maker after the I.B.M. executives refused to sign a similar document presented by Digital Research.

Mr. Rolander said that several months later I.B.M. returned with an offer that included a royalty, but that I.B.M. had made the decision to price the two competing programs differently.

Mr. Kildall remained involved as chairman of Digital Research until the company was sold to Novell in 1991. He founded a second company in 1985 called Knowledge-Set to develop one of the first consumer applications for CD-ROM, a disc-based version of the Grolier Encyclopedia.

More recently, he moved to Austin, Tex., to found Prometheus Light and Sound, which is developing a "home PBX system."

Several years ago, he moved back to the Monterey area, where he began working on a book titled Computer Connections, a history of the computer industry. Mr. Kildall self-published the book earlier this year.

Mr. Kildall was born in Seattle and received his Ph.D. in computer science from the University of Washington. He and Ms. McEwen were married in 1962 and divorced in 1983. He is also survived by two children, Scott, of San Francisco , and Kristin, of Seattle, and by his mother, Emma, and sister, Patricia Guberlet, both of Seattle.

1986 (January) article in "Picos Journal" IBM Picks the Winner by Kevin Strehlo

(all the following were copied in)

Sources : PDF at [HP003R][GDrive] / PDF with OCR at [HP003S][GDrive] / Raw text at [HP003T][GDrive]

Although a million CP/M computers have been sold, several million more run MS-DOS. How did the business of computing arrive at a standard?

It was n nice piece of business for Seattle Computer.Their project 10 write an operating system for the 8086 processor was under way anyway - they needed it for their own hardware. So getting some upfront money to finish the software. plus $10,000 for each customer Microsoft licensed it to, seemed like a great deal to Seattle Computer president Rob Brock.

Brock had his first glimmer of doubt about the wisdom of the deal one day late in 1980 when someone called Seattle Computer with a question.

"I'm with IBM." the voice said. ·•1 want 10 know something about the operating system you· re doing for us.·

"You're with WHO?" Brock asked, his voice rising incredulously. The man on the other end of the receiver said .. oops" and hung up.

When Brock mentioned the call to his employee Tim Paterson. who was writing the software to the specifications of Microsoft's customer, the 1wo laughed about it and wondered if that customer might really be Big Blue. It seemed odd and, even if the customer was IBM. not necessarily significant. The chance that TBM would be able to make much of a dent in the wide open world of microcomputers - far from the tightly controlled, large sale environment of IBM-seemed pretty small. No one company dominated the personal computer business, and it seemed unlikely that IBM would be more than just another player in a crowded field.

Who's the Boss?

The one thing that did dominate personal computing was the CPIM operating system. Nearly every microcomputer used it-even the Apple II. although it required an add-on board with a processor that ran the 8080 instruction set. It seemed unreasonable that even TBM would switch from an industry standard as strong as CP/M.

It was only when Paterson went to work for Microsoft a few months later that he learned it was TBM. But even a1 the introduction of the TBM PC in August 1981, it wasn't clear that the MS-DOS operating system Tim Paterson had written, dubbed PC-DOS by the press - although IBM called it simply DOS-would be important.

IBM introduced the PC with three operating systems-PC-DOS. the p-system and CP/M 86. Even the market research firm, Future Computing, wrote that the most significant aspect of the new machine was that the PC ran CP/M.

But CP/M was not to dominate the personal computing world any longer. and Future Computing quickly changed its tune. Later reports by the Texas-based market research firm rated a new computer largely on a single factor: whether it could run off-the-shelf PC-DOS applications.

Today. while laptop computers remain a stronghold for CP/M. the majority of the action in software development and microcomputer sales has been with MS/PC-DOS machines.

How did it happen? Why did CP/M lose out to MS-DOS? Why is CP/M still important in the world of microcomputers? And what's the difference anyway? ls MS-DOS any better than CP/M?

The best way to answer these questions is to go back to the beginning.

The Birth of CP/M

In 1972, while Gary Kildall was teaching computer science at the U.S. Naval Postgraduate School 1n Monterey, Calif .• he became intrigued with one of the fin.I of a new type of semiconductor part called a microprocessor. Although the four-bit Intel 4004 was too limited 10 do anything useful. Kildall's curiosity was piqued by the idea of a computer on a chip, and he decided 10 visit the Silicon Valley company that was making the things and see what else Intel had cooking.

Kildall and the small group of engineers working on microprocessors at Intel hit it off, and soon Kildall found himself commuting inland from his ocean-side home one day u week to work at Intel. Using a minicomputer 10 simulate Intel's new eight-bit microprocessor, the 8008, Kildall soon had created a version of the PL-I language that ran on it.

Kildall took one of the systems Intel sold as :in aid in developing software for the new microprocessors as partial payment for his work. Although his students at the Institute loved to play with the 8008-based microcomputer (which was soon upgraded with the more powerful 8080 and a high-speed tape reader), Kildall knew it needed real data storage if it was going 10 be truly useful. He did some work for Shugart Associates in 1972 in exchange for one of the early eight-inch floppy disk drives. But Kildall, no hardware ex:expert. failed in designing a controller board to interface the drive with his computer.

It was not until 1973, with John Torode from the University of Washington designing the hardware, that Kildall was able to write a simple operating system to control the transfer of d11a between the computer and the disk drive.

Despite the acronym DOS, which stands for Disk Operating System, there is more 10 such software than the kernel that Kildall had written to control the disk drive. However, Kildall wasn't focusing his attention on fleshing out his operating system kernel. The project he had grcnt hopes for was a microprocessor-based horoscope machine that he and a friend built and installed in Mores nil around San Francisco. Although the work didn't pay off in the anticipated deluge of quarters - the mechanical pan of the machine tended to jmn after ii had printed juM n few horoscopes- it rounded out Kildall's kernel.

When he tacked the software development tools (an editor. assembler and debugger that aided the production of language the microprocessor understood) he had used to develop the horoscope program onto his kernel, Kildall had all the tools needed 10 write and run useful programs.

When Kildall showed his Control Program/ Monitor (CP/M for short) 10 the powers that were at Intel. they said it had no commercial potential. The company thought its microprocessors would end up largely in watches, calculators and appliances. not in the kind of general-purpose microcomputers hobbyists were building.

Thus it was that Kildall, encouraged by his wife Dorothy, formed a company called Intergalactic Digital Research. placed ads in a few magazines and began to sell his CP/M. As the business became more serious, the Kildalls incorporated as Digital Research. Inc. (DR!). Dorothy. to avoid any · 'just his wife·· stigma, began using her maiden name, McEwen. When they sold IMSAI unlimited rights to CP/M for $25,000 in 1977, Digital Research became a full-time enterprise with Gary running research and development and Dorothy hand I ing the business side.

When the ability to utilize a disk drive and i1s Z80 microprocessor (which was faster than the 8080 bu1 ran the same instruction set) gave IMSAI an edge over i1s chief competition. MITS (maker of 1he first commercially successful personal computer. I.he Altair), other emerging microcomputer companies began to make the trek to Digital Research in Pacific Grove, a suburb of Monterey.

Tarbell Electronics. Digital Microsystems, Heath Electronics and the dozens of other companies that licensed the CP/M operating sys1em had good reasons for 1he 1rip. fl was cheaper to license the operating system Kildall hod developed and 1ailor i110 o particular Z80-based microcomputer than it was 10 develop an opera1ing sys1em from scratch. More important. a machine on which CP/M ran could run I.he application programs 1hat had been written for other CP/M machines. The only operating systems in competition with CP/M were limited to a single manufacturer's machine. and so CP/M and the Z80 microprocessor on which it ran became a kind of standard by default.

Not all computer manufacturers offered CP/M. Radio Shack substituted its proprietary TRS-DOS for I.he Z80-based TRS-80 computers, for example. Bu1 many TRS-80 users bought a version ofCP/M tailored for I.he Radio Shack machines by other companies. such as Pickles and Trout, in order to run all the CP/M software.

The most popular personal computer in 1980 was unquestionably the Apple II, which couldn't run CP/M because it was based on the 6502 instead of the 8080 or Z80. Although much credit for the success of Apple's machine has to be given to the first spreadsheet, VisiCalc (which at first ran only on I.he Apple II under Apple's proprietary DOS). many Apple II owners bought an add-on card for their machines 1ha1 included a 2-80 processor. memory and 1he CP/M operating sys1cm. This allowed I.hem 10 run 1he e,·er-increasing pool of business software being written for ORI's operating sys1en1, including WordMar and dBASE U.

The most popular of such cards was the Softcard, developed and sold by Microsoft. In fact. sales of the Softcard were so high that Microsoft became DRI's largest cus- 101nerf or CP/M. As I9 80 rolled 10a n end. 1h:11fa c1w as soon to take on an ironic twist.

CP/M Upgraded

When IBM decided 10 en1er the microcomputer business. it went to Microsoft on one-day'i. no1icc-for advice on wha1 kind of machine to build and for several key pieces of software. Ga1es had to cancel an appointment with Atari's chairman Ray Kassar in order to meet with mM. but he did it on 1he theory that if IBM was entering the microcomputer business as rumored, Microsoft should do anything it could to be a pan of it- because IBM succeeded at nearly everything it tried.

Microsoft's BASIC interpreter had been an integral pan of nearly every personal computer sold, and Microsoft's other languages were popular among software developers. Microsoft president Bill Gates knew microcomputers and the personal computer market as well as anyone. Thus it was no surprise when IBM asked Microsoft to make a proposal about developing languages for its planned machine and detail what the features of that machine should be.

No, it was no surprise that 1he computing industry veterans listened to president Bill Gates extol the new generation of 16-bit chips and the need for a disk drive- they were thinking of an 8-bit machine with a cassette interface. But it was a bit of a surprise when an mM official responded by asking Gates to sell IBM CP/M as well. Ga1es patiently explained that CP/M belonged to a company 1,000 miles down I.he coast. ORI, headed by Gary Kildall. Ga1es dialed DRI's number and handed I.he phone 10 an IBM representative, who made an appointment for the next day.

Legend has it that Kildall was out on a joyride in his plane when IBM came calling. Actually, Kildall already had an appointment with a customer in Silicon Valley the next day and, unlike Gates. decided to keep it. Af1er all, Dorothy McEwan always handled I.he business end of things with the firm's legal counsel anyway-why should a meeting with IBM be any different?

After concluding his business. Kildall flew back in the late afternoon and joined the meeting in progress, but things weren't going well. McEwan and DRJ's legal counsel Jerry Davis had balked at the nondisclosure agreement TBM had asked them 10 sign, because i1 contained a clause th:11 specified any infom1ation revealed in I.he meeting would become IBM's 10 use as it pleased. Since 1he meeting was about CP/M, McEwan thought such an agreement amounted to giving away the store, and refused 10 sign. The ll3M representatives were on I.he verge of leaving when Kildall arrived.

Kildall, familiar with IBM's way of doing things, knew IBM was an honorable company. The nondisclosure document ,vas meant to protect TBM from lawsuits in the even1 it later marketed similar technology that had been developed independently within IBM . With Kildall's reassurances. the nondisclosure agreement was signed. the meeting proceeded and. according 10 Kildall. went rather well.

Gary and Dorothy, as it happened, were about 10 leave on vacation and had seats on the flight that took the IBM representatives back to Boca Raton, Fla. Discussion continued amiably during the flight, according to Gary, and they agreed 10 get back together after the Kildalls returned from vacation .

It never happened . Bill Gates has said the problem was Kildall' s expression of reluctance to modify CP/M for IBM's requirements; Kildall believed a standard was a standard. lo any case, IBM eventually came back 10 Microsoft and asked if the Bellevue. Wash., firm could do an operating system. as well as the languages. It added only another 10 percent or so 10 the amount of code Microsoft was to write for the new machine; more important. Microsoft knew the operating system under development at Seattle Computer nearly fit the bill . When Microsoft had described that operating sys• tern in writing and IBM agreed it would be fine, provided a few changes were made. Microsoft negotiated rights to Seattle Computer's 8086 DOS.

What Microsoft had really contracted for was the work of a person it knew quite well. Seattle Computer's Tim Paterson had taken the first couple of cracks at designing Microsoft's Z80 Softcard card for the Apple before another engineer finished up. Microsoft was also familiar "'uh Paterson· s latest product. a processor board for scientific and engineering computer s based on the new 16-bit 8086 chip from Intel: Microsoft had used the board while writing its new BASIC for the 8086 and its compatible cousin. the 8088 . The board "''as one of the first implementations of Intel's new chip . It was done so early that the documentation from which Paterson began designing in June was dated Jul y. and talked about five and eight MH z chips when only four MHz chips were available.

The operating system Paterson was writing for his newbboard was to be CP/M compatible so that CP/M programs for the eight-bit Z80 could sim- ply be tranSlated and run unchanged on the new 16- bit 8086 . Paterson had no access to CP/M other than its documentation. however. and used as his chief model the CP ~I look-alike operating system called COOS that ran on the Cromemco [mis-spelled in the article as "Cromenco"] machine they used at Seattle Computing .

Thus it was that some of the improvements of Paterson's DOS over CP/M were accidental. If CP/M encountered an open disk drive door when it was trying to read from a disk. for example. it would crash . Paterson's operating system. like the CP/M look-alike he used as a model. responded to an open door with an "Abort. retry or ignore?" message.

Some improvements were Paterson's idea. however. You could halt a program that was ruMing under CP/~I (and COOS ) only by rebooting the machine . Paterson decided the ability to "break" the operation of a program and return 10 the operating system prompt made more sense . He also thought that the need for the PlP utility program to be on the disk v. hen you wanted to copy a file made no sense; nor did the terms PrP and · · =' · 10 describe the action of copying a file. Thus he decided to embed a file copying command with more sensible syntax right into his operating system. And whereas CP/M could destroy files if a user switched disks without telling CP/M such a switch had been made, Paterson made MS· DOS look at the disk in the drive before it v.·rote 10 it 10 prevent such disasters.

Perhaps the key thing Paterson tried 10 do was 10 speed up read and write operations. Borrowing from the compiled BASJC , he had helped Microsoft put on his 8086 board, he made his operating system keep information about files-called FA Ts (File Attribute Tables)-io memory instead of on the disk, which speeded file operations considerably.

It turned out that Paterson's DOS was not perfectly compatible with CP/M. however. because - at least according to Paterson some of the features he copied from CP/ M"s documentation did not work exactly as documented.

The key difference between the operating systems, however. was due to differences between the chips for which they were written. The Z80 processor that CP/M was designed for could address only 64K bytes of memory. while the 8088 and 8086 processors Pater son wrote his DOS for could address one Megabyte ( I.OOOK bytes) of memory. IBM. through Microsoft. told Paterson to use only 640K bytes or that memo ry and reserve the remaining 360K bytes for the system's use. Even so. it was hard 10 imagine that programmers would ever need more than a 10-fold increase in memory. It augered much-improved programs for the next generation of personal computers.

This key improvement of Paterson's DOS over CP/M was also a feature of Digital Research's CP/M-86. of course . since it also ran on the more advanced chips. So why did MS-DOS win?

IBM Picks the Winner

CP/ M-86 was only a plan on a blackboard on that fateful day in 1980 when IBM called on DRJ. Unfortunately. IBM never called back. and Kildall was unaware of the project's process until, shortly before the IBM PC was to be introduced in August of 1981. IBM returned and asked him 10 write an operating system for its new machine. Since demand for the Z80-based CP/M had not abated. not much work had been done yet on CP/t,.1 for the 8086: a team immediately got to work.

In retrospect. it is clear IBM wanted CP/M only as a backup in case its new operating system did not gain support among third party developers. IBM had clearly stacked the cards in its DOS's favor. The price of PC-DOS was $40 compared to $250 for CP/M-86. Moreover. DRI was unable to ship CP/M-86 for a full year after the PC's introduction. whereas PC-DOS was not only ready on the day of introduction. the programs mM sold for the machine ran on it. CP/M-86 never overcame Dos's head-start.

As it turned out. the need for MS-DOS 10 have CP/M compatibility was not significant. Rather than translate old programs that ran in 64K. most developers wrote new software that took advantage of the increased addressing space of the new IBM machine's operating system. Without it. the power and ease of use of such programs as Lotus 1-2-3. dBASE III and MultiMate would not have been possible. Without that extra addressing space. the IBM PC could not have been the overwhelming success it was.

The Best OS for Picos

For pico machines. however, such power is not always necessary . If a machine's intended tasks are note taking. simple communication via modem. limited number crunching and simple custom applications. the extra expense of more memory and a more powerful processor may not be jus tified. For many laptop machines, CP/M and a ZSO is just the ticket .

On the other hand. if compatibility with all the software one uses in the personal computer back at the office is called for, MS-DOS and the 8088 is the operating system of choice.

MS-DOS bas continued 10 improve. but many of the improvements are of limited value for today's picos. Versions 2.0 and higher of MS-DOS incorporate a hierarchical file structure that facilitates keeping things straight on a large capacity disk, a need that's less than dire on today's laptop machines, since the power draw and bulk of large capacity bard disks is currently more than can be handled .

Yet, there can be no doubt that MS-DOS has eclipsed CP/M. Although a million CP/M computers have been sold. several million more run MS-DOS. In the world of operating-system specific magazines, it is CPIM Users Guide versus PC. PC World, PC Tech Journal, and PC Week. In tile world of software publishing. tile odds are even higher in favor of MS-DOS. And if you need further proof , look no further than 10 Digital Research ·s latest operating system, Concurrent DOS: it is MS-DOS compatible. The tables have been turned.

Dr. Dobb's Special Report, Spring 1997

by Michael Swaine

Michael, Dr. Dobb's Journal's editor-at-large, can be contacted at or

In the early days of the personal-computer revolution, the atmosphere at those shoestring startup companies with names like "Golemics" and "Loving Grace Cybernetics" was often more academic than businesslike. This collegiate ambiance touched everything, from the ways in which decisions were made and respect allocated, right down to sophomoric pranks and styles of dress.

There's a fairly obvious reason for this, or at least for some of it: Microcomputers were a new field, ripe for rapid advances, and that's a situation that fits neatly into a collegial atmosphere in which information is openly shared. When discoveries are freely shared, it's easier to build quickly on those discoveries; conversely, when progress is rapid, there is less reason to hold onto yesterday's discoveries. This natural synergy between rapid progress and information sharing is one key factor in the spectacular growth in the use and acceptance of computers over the past 20 years. It's one of the reasons that the personal-computer revolution really has been a revolution.

In time, companies like Apple and Microsoft would emphasize this synergy, explicitly calling their corporate headquarters "campuses." Even today, computer hardware and software companies often have a lot of the look and feel of grad school. But this predilection for a collegial atmosphere predates Apple and Microsoft. And while it didn't start there either, it was nowhere more evident in the early days than at one of the first personal-computer software companies—Digital Research. Digital Research could hardly have been anything but collegial: The company that gave personal computers their first operating system was the brainchild of a perpetual academic and born teacher. His name was Gary Kildall.


Gary Kildall seemed fated to be a teacher. His uncle would later claim that it was what Gary had always wanted. Teaching certainly was in his blood: The Kildall family actually owned and operated a small college. More precisely, it was a school for the teaching of navigation, based in Seattle, Washington. The Kildall College of Nautical Knowledge, the family called it; it was founded in 1924 by Gary's grandfather. Many Kildalls taught or worked at the school, including Gary himself, for a while, after graduating from high school.

But he had decided that year that he was going to be a math teacher, so he enrolled at the University of Washington. Newly married to high-school sweetheart Dorothy McEwen, he buckled down and applied himself to his studies, trying to put a childhood of mediocre grades, fast cars, and pranks behind him.

Somewhere along the way to a math degree he got hooked on computers. On finishing his degree, Gary went on to graduate school in computer science. He was still headed for a career in teaching, only now it would be teaching computer science at one of the few colleges that had programs back then. But there was a hitch. He had joined the Naval Reserve, and it was the '60s, with the Vietnam war in full flower. The Navy gave him a choice: Go to Vietnam or take a faculty position at the Naval Postgraduate School in Monterey, California.

Gary thought about it for a microsecond and chose Monterey. Even when the Navy told him what to do, the answer was the same: Teach.


It was in Monterey that Gary created CP/M, the program that brought him success and that became the unquestioned standard operating system throughout the microcomputer industry. CP/M was a good product and deserved, for many technical reasons, to be the standard. But getting there first always helps, too. And CP/M actually appeared a year before the first commercial microcomputer arrived on the scene.

Unlike operating systems before and since, CP/M was not the result of years of research by a team of software engineers. It was, like most software of its time, the invention of one individual. That individual was Gary Kildall, and if chance put Kildall in just the right place at just the right time, you would have to say, in retrospect, that chance chose well. As it did with Bill Gates, chance spoke to Gary Kildall through a note on a college bulletin board, college bulletin boards apparently being the Schwabb's Drug Store of personal-computer fame.

The note talked about a $25 "microcomputer," a pretty good deal even at 1972 prices. It was actually describing not a computer but the first microprocessor, the 4004 that Ted Hoff had designed at Intel. Presumably, this note was an advertisement torn from a recent issue of Electronics News. Intel had hired Regis McKenna to write the ad at Hoff's urging. Hoff was convinced that techies would see the virtue of this new device, this general-purpose processor, and urged that it be advertised, extravagantly but not altogether inaccurately, as a "microcomputer." This would make it absolutely clear that it was not just another limited-purpose device, but something fundamentally different. Hoff was sure that engineers and programmers would get it.

Kildall got it, literally, sending off his $25 for one of the first Intel 4004 chips.

It was 1972. Kildall was busy teaching computer science at the United States Naval Postgraduate School in Monterey. He and Dorothy (and son Scotty) had moved into a house in neighboring Pacific Grove. The Seattle natives loved this scenic coastal town, with its laid-back, fog-draped ambiance. The place suited the easy-going professor. Whether in class or among family and friends the lanky, shaggy-maned Kildall spoke with the same soft voice, the same disarming wit. Although he was teaching at a naval installation, he wouldn't have been out of place on any college campus in his customary sport shirts and jeans. When he had a point to make he would often cast about for chalk or a pencil; he was an incurable diagram drawer.

Gary was happy in his marriage, happy to be living by the ocean, happy not to have gone to Vietnam, and most definitely happy in his job. He loved teaching, and the work left him time to program. Nothing in his life was preparing him to run a business, to handle a spectacularly successful software company supplying the essential software for hundreds of different computer models in an industry running wild. Everything argued for his staying right where he was forever, teaching and programming. At first, the 4004 seemed to fit in with that scenario.

Gary started writing programs for the 4004. His father, up at that little navigation school in Seattle, had always wanted a machine that would compute navigation triangles. Gary made that his project, writing some arithmetic programs to run on the 4004, thinking idly that he might come up with something that his father could use. He was really just fooling around with the device, trying to see how far he could push it, and with what speed and accuracy.

Not all that far, he soon learned. The 4 in 4004 meant that the device dealt with data in 4-bit chunks—less than a character. Getting anything useful done with it was a pain, and performance was pitiful. Although he was frustrated by the limitations of the 4004, he was fascinated by what it promised. Early in 1972 he visited Intel and was surprised to see how small the microcomputer division (dedicated to the 4004 and the new 8008) was: The company had set aside only a few small rooms for the entire division. Gary and the Intel microcomputer people got along well, though, and he began working there as a consultant on his one free day a week. He spent months programming the 4004 in this day-a-week mode until he "nearly went crazy with it." He realized—and it was a radical idea for the time—that he would never go back to "big" computers again. Which is not to say that he stopped using "big" computers. With both the 4004 and the significantly more powerful 8008 that he soon moved on to, he was doing his development work on a minicomputer, much as Bill Gates and Paul Allen did later in writing software for the breakthrough MITS Altair computer. Like Paul Allen, he wrote programs to simulate the microprocessor on the "big" minicomputer, and used this simulated microprocessor, with its simulated instruction set, to test the programs he wrote to run on the real microprocessor.

But unlike Gates and Allen, Gary had the benefit of a development system, essentially a full microcomputer spun out around the microprocessor, so he could try out his work on the real thing as he went along. In a few months he had created a language implementation called "PL/M," a version of the mainframe language PL/I that was significantly more sophisticated than Basic.

The Lab

As partial payment for his work, Gary received a development system of his own, which he immediately set up in the back of his classroom. This allowed him to combine his new obsession with microcomputers and his love of teaching. The system in the back of the classroom became the Naval Postgraduate School's first—if not the world's first—academic microcomputer lab.

And academic it was. This was not just Gary's toy; he used it to teach students about the technology, and encouraged them to explore it. His curious students took him up on it, spending hours after class tinkering with the machine. When Intel upgraded this Intellec-8 from an 8008 to its new 8080 processor and gave Gary a display monitor and a high-speed paper tape reader, he and his students were working with a system comparable to—favorably comparable to—the early Altair computer before the Altair was even conceived.

Gary realized, though, that he was missing an essential ingredient of a really useful computer system—an efficient storage medium. In the early '70s, paper tape was one of the standard storage media, along with the infamous punched card. Neither was very efficient, and the issue was particularly critical on microcomputer systems because the relatively slow microprocessors couldn't offset the inherent slowness of the mechanical process of punching holes in pieces of paper.

IBM had recently introduced a new storage medium that was much faster and more efficient. It was based on the existing technology of recording data as patterns of magnetization on large rapidly spinning disks, a medium that had everything going for it except price. But IBM engineers figured out how to scale down this technology to something smaller and more affordable, creating the floppy-disk drive.

One $5 floppy disk held as much data as a 200-foot spool of paper tape, and a floppy-disk drive could be had for around $500. The combination of the microprocessor and the floppy disk drive meant that, in Kildall's words, "It was no longer necessary to share computer resources." In other words, the elements of a personal computer were at hand. Well, most of the elements. Gary soon found that some important components were still annoyingly missing.

By this time, an industry was developing to create these floppy-disk drives in volume, and Shugart was the pioneer of this industry. Once again, Gary traded some programming for some hardware, getting himself (and the microcomputer lab) a Shugart disk drive. But for the disk drive to work with the Intellec-8, another piece of hardware was needed, a controller board that fit in the Intellec-8 and handled the complicated communication between the computer and disk drive. This piece of hardware, unfortunately, did not exist.

Gary tried his hand more than once at building the controller. When that proved more challenging than he expected, he explored the idea of using a different magnetic medium—ordinary audio tape, mounted on a conventional tape recorder. His efforts in interfacing a tape recorder with the Intellec-8 were no more successful than his efforts to build a disk controller. It soon became clear that his considerable programming expertise was no substitute for the hardware knowledge needed to build a device that would connect the Intellec-8 with an efficient storage device. It is worth noting that Kildall was well ahead of his time: When MITS, IMSAI, and other companies began marketing microcomputers, they began with paper-tape or magnetic-tape storage. It would be several years yet before disk drives came into common use on microcomputers.

Finally, in 1973, admitting hardware defeat, Gary turned to an old friend from the University of Washington, John Torode. Torode would later found his own computer company, but in 1973, he was just doing a favor for his old friend. "John," Gary said, "we've got a really good thing going here if we can just get this drive working." Torode got the drive working.


Meanwhile, Gary found himself involved with another hardware engineer on another microprocessor-based project. This project, for all its apparent frivolousness, was the first hint of any genuine commercial ambitions on the part of Gary Kildall. The project was the ill-fated Astrology Machine.

Ben Cooper was a San Francisco hardware designer who had worked with George Morrow on disk systems and later would, like Torode, start his own computer company, Micromation. In the early '70s, he thought he could build a commercially successful machine to cast horoscopes, and he enlisted Gary's help.

The business was not a success—"a total bust," Gary later called it. Still, the Astrology Machine gave Gary the first field test of several programs he had written and rewritten over the past months: a debugger, an assembler, and part of an editor. He also wrote a Basic interpreter that he used to program the Astrology Machine. Since, for Gary, there was little distinction between his academic work and his commercial or consulting work, he passed on the tricks he came up with to his students. He passed the tricks he came up with in writing the Basic interpreter on to a young naval officer named Gordon Eubanks (today, president and CEO of Symantec). All the programs, with the exception of the interpreter, became part of the disk operating system he was writing to control the controller that Torode was building.


As they worked on the hardware and software to make the computer and disk drive work together, Kildall and Torode traded thoughts on the potential of these microprocessors. Neither of them thought that the computer system in the back of Gary's classroom would have a very large market. Microprocessors, they thought, as most everyone at Intel itself thought, would see their chief use in smart consumer devices, like blenders and carburetors. Kildall and Torode did see a small market for development systems like the Intellec-8, but only among the engineers who would be designing and developing those smart blenders and carburetors. This view was fostered by Intel management. In fact, Intel's top brass was even more conservative about the potential market for the devices than Kildall. When Gary and some Intel programmers wrote a game that ran on the 4004 and suggested that Intel market it, Intel chief Bob Noyce vetoed it. The future of microprocessors was elsewhere, he told them; "It's in watches."

When Intel passed on marketing the game, Gary wasn't fazed. He more or less agreed with Noyce about the market. But when the company turned down a piece of software closer to Gary's heart, he began to think that he might have a better sense of the value of microcomputer software than the powers-that-be at Intel.

When Torode finished the controller, Gary polished the software to control it. This was a disk operating system, the first such for a microcomputer, and Gary called it CP/M, for "Control Program/Monitor" or "Control Program for Microcomputers." He presented it proudly to Intel and suggested a reasonable price for it: $20,000. Intel passed. The thinking, apparently, was that the target market for Intel development systems was people like Gary, and since Gary had written some impressive software for the 4004, 8008, and 8080 without an operating system, clearly an operating system was not necessary for the target market. Not $20,000 necessary, anyway. Intel did buy Gary's system programming language, PL/M, but not CP/M.

Gary had been doing his consulting and development work under the name "MAA," or "Microcomputer Applications Associates." MAA (that is, Kildall) completed CP/M in 1974. It was a spartan system, containing only what was essential. It was also remarkably simple, reliable, and well suited to the limited microcomputers of the day. Gary believed in CP/M, and if Intel didn't want it, he was sure there were a lot of hardware hackers and engineers who would. He could sell it himself.


Gary might have been content to run a small ad in the back of one of the electronics magazines, maybe putting a note on that bulletin board. What actually ensued was a little more ambitious. At Dorothy's urging, the Kildalls formed a corporation. Gary would do the programming and Dorothy would run the business. She started using her maiden name, McEwen, so she wouldn't be seen as just "Gary's wife." They incorporated, dropping the MAA name and calling their corporation "Intergalactic Digital Research Inc." This was later shortened to Digital Research Inc. And they started selling CP/M.

It was the beginning of the personal-computer revolution. (Everything Gary had been doing up to then was prerevolution.) The Altair had been announced, and a flock of other startup companies were starting work on microcomputers, usually kits but sometimes assembled systems, some with a paper tape interface but many with no satisfactory provision for data storage. They needed disk drives, and they needed a disk operating system.

In those days, there was no model for software pricing, so Digital Research's first customers got some pretty good deals. When Tom Lafleur came to them wanting a license for his company, GNAT Computers, Dorothy gave him unlimited rights to use CP/M as the operating system on any product his company produced, for a whopping $90. Within a year the price had gone up by a factor of 100.

The deal with IMSAI in 1977 was the turning point, and Dorothy knew it. Until 1977, Digital Research was, like most of the industry, little more than a hobby. And until 1977, IMSAI had been purchasing CP/M from Digital Research on a single-copy basis. But IMSAI, with its grandiose plans to sell thousands of floppy-disk-based microcomputers for use in businesses, wanted to restructure the deal. Marketing director Seymour Rubenstein (later of WordStar fame), a shrewd negotiator, haggled with Dorothy and Gary, ultimately arriving at a license fee of $25,000. Rubenstein gloated. He felt that he had virtually stolen CP/M from them. He respected Kildall's programming expertise, but thought the Kildalls were babes in the woods when it came to business. Perhaps they were, but the Kildalls' perspective was a bit different. After the IMSAI deal, Digital Research was a real, full-time business. The IMSAI deal also solidly established CP/M as the standard, and other companies followed IMSAI's lead in licensing it. CP/M quickly became and remained so solid a standard that, until IBM introduced a personal computer, Digital Research faced no serious competition.

And the programmers who would provide that competition were still working at MITS in Albuquerque.


After the IMSAI deal, Digital Research began to grow rapidly. Although it wasn't a financial necessity, Gary continued to teach at the Naval Postgraduate School for years after the founding of DRI. DRI itself felt very academic. Relationships tended to be collegial, the atmosphere casual, discussions animated and cerebral. Or not so cerebral: The atmosphere sometimes was less like a college classroom than a college dorm. Gary liked to rollerskate through the halls, and once conducted an employee interview in a toga.

The staff was young, eager and deeply loyal.

"Gary built a campus in Monterey," Alan Cooper would later remember. DRI "was collegial in every respect." It was only when the company didn't function like a college that Gary got frustrated. Employees would come to him expecting him to solve business problems, marketing problems, personnel problems. He didn't know the answers; didn't really want to think about the problems. What he wanted to do was write code. "Code was his element," Cooper says.

So he wrote code, keeping out of the business end of things as much as possible. He improved CP/M, making it more portable. Certain features of the program were logically independent of the hardware, while others were intimately dependent on the exact features of the machine the program was running on. Gary shrewdly carved out the smallest possible set of machine-dependent elements, and made them easily field customizable. The result was that DRI could write one version of CP/M, and hardware vendors, field engineers, or whoever could customize it to their particular hardware configuration. This approach would be reinvented years later as the "hardware abstraction layer," but Gary had it down cold in 1978.

Even his second-in-command was—let's not mince words—a total code geek. Tom Rolander was exactly the sort of person Gary liked to have around him: just a kid in a candy store when it came to programming, without a business bone in his body. There weren't many business-boned bodies at DRI. But the company did have the operating system that you pretty much had to run on your computer system. It had the market because it had the technology.

DRI didn't actually have the entire market. In the early '80s, the Apple II was the largest-selling machine that did not run CP/M, but it was also the largest-selling machine, period. The base of software for CP/M systems was large and growing, and Microsoft, seeing an opportunity, made an uncharacteristic move into hardware: It developed a SoftCard for the Apple II that would let it run CP/M. Then it licensed CP/M from DRI to sell with the SoftCard. Soon Microsoft was selling as much CP/M as DRI.


Gary had moments of doubt about whether this was what he wanted to be doing with his life. In one of the darkest of those moments in the late '70s, Gary passed the parking lot by on his way in to work, and continued around the block, realizing that he just couldn't bring himself to go in the door. He circled the block three times before he could force himself to confront another day at DRI.

Later, in frustration, he offered to sell the company to friends Keith Parsons and Alan Cooper. Parsons and Cooper were running one of the first companies to deliver business software for microcomputers, a kitchen-table startup named "Structured Systems Group." Gary was fed up with all the pointless games and distractions of business. They could have the whole operation for $70,000, he told them. As for him, he would go back to teaching.

It was a dream: There was no way it would have happened. Keith and Alan had little hope of coming up with $70,000, and Dorothy would never have okayed the deal. Dorothy's self-taught business skills would be sorely tested in the near future, but in the late '70s, she knew well enough that the Kildalls had something worth a lot more than $70,000 in DRI. By 1981, it was obvious to the dullest wit that she was right: In that year, there were some 200,000 microcomputers running CP/M, in more than 3000 different hardware configurations, a spectacular testament to the portability that Gary had designed into CP/M. That year, the company took in $6 million. Digital Research employed 75 people in 1981 in various capacities. It had come a long way since its inception only seven years earlier in Gary and Dorothy's house.

That was also the year that IBM announced its plan to build a personal computer.

The story has been told often—and variously—of how Digital Research lost the IBM operating-system contract to Microsoft, and how this made Microsoft's success. It had a big impact on DRI, too.


From that point on, DRI was going in several directions at once. DRI was one of the first personal-computer companies to seek venture-capital funding to go public. The VCs were willing, but insisted that strong management be brought in to get the business under control. Gary was thrilled by the idea of bringing in someone on whom he could unload all the annoying business decisions. John Rowley got that job. Gary quickly disappeared into the fold of Tom Rolander and the developers, and was rarely seen elsewhere. In particular he was rarely seen with John Rowley.

Personable, bright, enthusiastic, Rowley nevertheless struck some around him as just a bit unfocused. He was routinely late to meetings, and he called a lot of them. If there was an overall strategy to his actions, it wasn't obvious. Sometimes, one employee later recalled, he forgot to pay his bills—his own bills, that is—and dunning letters would find him at work. He was boundlessly enthusiastic, but as company direction shifted from week to week, the optimism got old quickly.

But Rowley may very well have been doing the best anyone could under the circumstances. The circumstances being that the company remained Gary's company, and actions Gary took or authorized could drive the company into one market or another. And did.

Gary wrote a version of the programming language LOGO for his son Scott. He just thought it would be a cool thing and that Scott could learn about programming and logic from it. Then he handed it to Rowley, saying, what should we do with this? And that was how DRI LOGO became a product. Tom Rolander was fascinated with the Apple LISA (the slo-ow predecessor to the Mac), and set one up in his office. He messed with it for quite a while, but nothing ever came of that. Fortunately. Gary was also intrigued by the LISA/Mac user interface, and began exploring that realm. The company's focus was supposed to be operating systems, but the result of Gary's interest in user interfaces was that one of the many varieties of CP/M then under development got sidetracked into a user-interface shell that would sit atop an operating system. That was "GEM," a Mac-like UI for non-Mac computers. Apple thought it was a little too Mac-like and threatened to sue, and DRI caved. It couldn't have been lost on Gary that Microsoft, which also had a Mac-like UI called "Windows," did not (then, at least) get sued.

The company was making lots of money at first, but it was also making some serious mistakes. Not keeping customers happy was one of the worst. DRI in the early '80s occupied a role similar to Microsoft in the '90s: Everybody depended on it and resented it for that. But DRI just wasn't sufficiently responsive to customer complaints and requests.

Alan Cooper blames Gary. When anyone would tell Gary that he ought to add a particular feature, "Gary would try to argue you out of it." He didn't want to pollute good code with kludged-on features. The PIP command exemplified his attitude. In CP/M, you "Pipped" to drive B from drive A; in MS-DOS, you "Copied" from A to B. Gary thought that there was nothing wrong with using the command PIP to copy, and that any halfway intelligent person could master the concept that you copied (or pipped) from right to left. Bill Gates let people do it the way they wanted. "That difference in attitude," Cooper says, "is worth twenty million dollars." Gary didn't care. What Gary was interested in was inventing.

On Cooper's first day at DRI, he recalls, Gary took him to Esther Dyson's high-level industry conference. "He gave me John Rowley's badge, and we climbed into his Aerostar and flew [to Palm Springs]. I remember running into Bill Gates and saying I had just joined Gary Kildall in research. I said I was working in research and development. He chuckled that Gary had set up an R&D department. He considered R&D to be part of what everybody did. Bill was right."

Gary, however, wanted to segregate R&D from the mundane concerns of the business. He wanted a skunkworks, a small crew that pursued projects on the basis of interest, just as pure academic researchers follow the interesting idea rather than worry about someone's bottom line. And he did.

Some good ideas came out of the skunkworks, although the best mostly came from Gary. He did groundbreaking work on CD-ROM software and on interfacing computers and video disks. A company, KnowledgeSet, came out of that work. So did a CD-ROM-based Grolier's Encyclopedia, a product that showed everyone how to do CD-ROM content. Microsoft's later enviable position in the CD-ROM content market owes a lot to Gary Kildall's good ideas and Bill Gates' ability to spot a good idea and pounce on it.

In the midst of the rest of the confusion, Gary and Dorothy split up. It was more than a private, personal matter, since both of them stayed at DRI. So did the other woman. The atmosphere grew more tense than it already was.


As Digital Research floundered and flailed, Microsoft flourished. Sometimes Microsoft flourished in ground cleared by Gary Kildall, as in the case of MS-DOS, as in the case of multimedia/CD-ROM technology. The legend of Bill Gates as the technological genius who invented everything in the personal computer realm grew, while a dwindling percentage of computer users had even heard of Gary Kildall.

Kildall was always gracious about this.

At least publicly he was gracious. Inwardly, he hid a bitterness that few ever saw. One day, though, Cooper got a glimpse of Gary's depth of feeling about proper credit for invention.

"Kildall took me aside once, about '83. [He started] talking about Apple. He opened this door, and I saw the bitterness: 'Steve Jobs is nothing. Steve Wozniak did it all, the hardware and the software. All Jobs did was hang around and take the credit.'" Cooper was not blind to the implications of this. Kildall resented that Gates, this dropout, this businessman, was getting credit for things that Kildall had invented. "All of a sudden there was this cauldron of resentment. It must have tortured Gary that Bill Gates [got all the credit]."

Whether Kildall's resentment of Bill Gates was fair or not—and it is important to repeat that it was never publicly expressed—it was probably inevitable. When you look at the allocation of credit in the computer industry from a collegial, academic perspective, it does seem that Bill Gates and Microsoft have, now and then, got credit that rightfully belonged to others. It's hard to defend the idea that this is the right perspective to use in looking at an industry, but a collegial, academic perspective was exactly the perspective from which Gary Kildall viewed his world. He could hardly help but feel wronged.


Gary never went back into academia, staying with DRI to its end, when it was sold to Novell in 1991. At Novell, all traces of DRI products and projects quickly dissolved and were absorbed like sutures on a healing wound.

Gary then moved to the West Lake Hills suburb of Austin, Texas. The Novell deal had made him a wealthy man. His Austin house was a sort of lakeside car ranch, with stables for 14 sports cars and a video studio in the basement. He owned and flew his own Lear jet and had at least one boat. In California, he kept a second house: a mansion with a spectacular ocean view on 17 Mile Drive in Pebble Beach. He started a company in Austin to produce what he called a "home PBX system," called "Prometheus Light and Sound." He did charitable work in the area of pediatric AIDS. It should have been a good life, but all was not sublime. His second marriage was ending in divorce, and there were signs that lack of credit was continuing to eat at him.

Then, while in Monterey in 1994, Gary Kildall died from internal bleeding on July 11, three days after falling down in the Franklin Street Bar and Grill in downtown Monterey. He was 52.


And there the history of Gary Kildall and Digital Research ends. But it is more than mere politeness to say that a legacy remains. In March, 1995, the Software Publishers Association posthumously honored Gary for his contributions to the computer industry. They listed some of his accomplishments:

  • He introduced operating systems with preemptive multitasking and windowing capabilities and menu-driven user interfaces.

  • Through DRI, he created the first diskette track buffering schemes, read-ahead algorithms, file directory caches, and RAM disk emulators.

  • In the 1980s, through DRI, he introduced a binary recompiler.

  • Kildall defined the first programming language and wrote the first compiler specifically for microprocessors.

  • He created the first microprocessor disk operating system, which eventually sold a quarter million copies.

  • He created the first computer interface for video disks to allow automatic nonlinear playback, presaging today's interactive multimedia.

  • He developed the file system and data structures for the first consumer CD-ROM.

  • He created 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.

That's a good list, as far as it goes. But friends and students might make a different list, citing his gift for explaining, his patience, his high standards in his work, his generosity. Those who knew him in later years in Austin might cite his pediatric AIDS work.

These things are worth remembering, and represent a real positive impact on the world, whether remembered or not.

As for Kildall's place in computer history, it certainly shouldn't be as The Man Who Wasn't Bill Gates. "It was" as his friend and colleague Alan Cooper puts it, "Gary's bad luck that put him up next to the most successful businessman of a generation. Anyone is a failure standing next to Bill Gates."

He was by any measure an admirable man, a business success, an inventor of importance, a humanitarian.

And, above all, a teacher. "When Fortune magazine writes about Gary Kildall," Cooper said, "they don't see him in his natural habitat: a university." Kildall was never happier than when he was in that academic habitat, solving tough problems and sharing the solutions that he discovered openly with others.

He should have stayed in academia, a relative later said. It's what he loved. But in a sense, he never really left.

Copyright © 1998, Dr. Dobb's Journal

Dr. Dobb's Web Site Home Page

The true story or ... Gary Killdall, inventor of the smart phone

by George Wenzel

I try to tell Gary’s story to anyone that will listen. I tried to have everything I know about Gary added to the Wikipedia page, and there I was out voted... If it is reported in the press, it has more weight than if someone that was there reports what really happened.

Remember the story about Gary flying his plane instead of meeting with IBM when they were wanting to put CP/M on the PC? And how missing that meeting caused IBM to go with msdos?

That story is rubbish.

The PC was shipped with a crappy, buggy version of msdos, because msdos was cheap. The user was expected to pay $250 for CPM if they wanted to run the current commercial software (wordstar and others). CP/M was an upgrade path for the PC. The real story was that IBM thought of CP/M as the "good stuff" and it was a premium offering. But that isn’t even a tiny part of the whole story...

Did you ever own an original IBM AT? On the IBM AT, the power-up post routine printed the words "AT Multiuser System" at the top of the screen during power up. What the heck is the AT Multiuser System??? The AT prototypes didn’t boot msdos, they booted a secret new OS. This new OS (I don’t know the code-name for it) was a multiuser dos. The design was simple, you buy an AT, and it comes with one or more 8 port serial cards. You buy Wyse terminals (the ones with the PC Emulation mode( as opposed to modes like VT100 emulation)) and put one one each desk, then you run serial cables to your AT. This OS was a true multitasking OS, and the AT was a small cheap minicomputer. THAT was what the AT was designed to be. Period.

So what the heck happened?

IBM had a successful project, the first manufacturing run filled the warehouse, the software was ready, and it was time to start packaging the retail boxes. The first of the manufactured systems used up the last of the initial supply of 286 chips, before Intel switched to a lower-cost run of the 286 chips. The new 286 chips had some minor changes to increase yields, allowing the price to be lowered. Apparently the yields were low on the original version that IBM started manufacturing with. At some point IBM found a bug in the OS that slipped through the QA tests... It was a subtle bug that only had an impact when the machine was multitasking with multiple users, and as it turns out it was only present on the systems with the new 286 chips.

There was a lot of finger pointing and hand-wringing going on over it. Something was broken in the protected mode functions. IBM sales execs were either going to have to insist Intel use the more expensive low-yield version of the 286 chip, OR IBM was going to have to scrap the multiuser system. IBM is managed by the sales department. Someone in sales did the math... we use the expensive 286 chip, and sell one AT to each customer’s office of 15 to 20 people... OR we sell them 15 or 20 machines with a cheaper chip. Which makes more money? It was decided that scrapping the multiuser system would increase system sales volume in theory. Even if the 15 to 20 machines were PC’s instead of AT’s, more money was made selling more systems than selling one.

So what happened to the multiuser system? The 8-port serial boards were ground into dust, except for a few units that escaped with the beta testers (I used to have a bunch of these). The Wyse terminals still had the PC emulation mode, but the expected sales volume of those never happened, so Wyse suffered as their R&D investment in the project was scrapped. DR got paid for their work on the OS, but they never got to see any revenue from sales. Bill Gates went from being a footnote in history to being who he is today. The first widely