CP/M and Digital Research Inc. (DRI) History - References

IMSAI, DRI, Kildall materials and sources

DRI original product documents, and code on diskettes, provide dates for various versions of CP/M. Some of these are described on my DRI products Web page.

IMSAI references:
IMSAI original documents and diskettes from my IMSAI document collection
IMSAI's Todd Fischer's email interview with Joe Killian about Kildall, Glenn Ewing and IMSAI's IMDOS development.
my summary of IMDOS and CP/M development from comp.os.cpm discussions of June 2006;
An early version of IMDOS is at the "unofficial" CP/M Web site;
various posts and emails from Todd Fischer as quoted or referenced on my IMSAI Web page.

Histories of Gary Kildall

A early history of Gary Kildall is in Michael Swaine's "Dr. Dobbs Special Report" of Spring 1997. Swaine wrote many times about Kildall, including the book "Fire in the Valley" which I discuss in detail below.

A copy of "From backyard to big time; the history of CP-M" By: Thom Hogan, Creative Computing Vol 9 #11, Nov 1983; is at the Web page linked here. This site has other Creative Computing articles.

An account of Kildall's early work, written by Sol Libes apparently in 1995 as "The Gary Kildall Legacy", is discussed elsewhere on this site.

IN 2004, Sir Harold Evans and collaborators wrote the book "They Made America" which includes a chapter on Gary Kildall's life and work. Follow the link for details.

Upside magazine, a business-and-technology publication which filed for bankruptcy in 2002, published in Nov 1994 (after Kildall's death) an unflattering account of Gary Kildall's later years called "Fatal Flaw" It was written by G. Pascal Zachary, a Wall Street Journal reporter and technology author. The December 1994 issue had a letter to the editor about Kildall, written by Rich Roth . Roth says he, Roth, was the author of CDOS for Cromemco, among other claims; Roth has similar claims posted elsewhere on the Web. Roth's letter says: : "In 1976, myself and Ed Hall at Cromemco tried to get Kildall to work with us to add flexibility in CP/M to handle new 5-1/4 inch disk drives and [Kildall] would not even meet with me....I ended up writing a new operating system called CDOS...". Issues of drive support are consistent with changes from CP/M 1.2 to 1.3 to 1.4 at IMSAI. Some of Cromemco's CDOS operating system manuals, in later but not earlier editions, refer to a license with Digital Research specifically in order to use features of CP/M V1.3.

"digitalresearch.biz" is a Web site dedicated to Dr. Gary Kildall, CP/M and Digital Research history, and the employees of DRI. That site reports a private reunion of DRI employees which occurred September 4th 1999. A document on that site describes the reunion in photos, and includes a brief history of Digital Research and early CP/M development. It and other documents on the site, reference Kildall as saying 1974 when CP/M first ran, and the site has other information. The site is apparently owned by "Digital Research - MaxFrame Corporation". Most documents and information on the site are no later than 2005 but some personal portions were were updated in 2008 so the site is apparently not "dormant".

As of 2008 I found a nice description of The Intel system model likely used by Kildall to first run CP/M. It's on this Italian Web site which shows an Intel Intellec 80 system. The description of how Kildall obtained one of these from Intel sounds correct.

In 2014, the IEEE and the Computer History Museum honored Dr. Gary Kildall with a commerative plack on the site of DRI Inc's first office building.

Early DRI references in Dr. Dobbs Journal, Byte, books, articles

"A Heathkit method for building data management systems". Gary Kildall, Naval Postgrad. School, and Earl Hund, Univ. of Wash. April 1971, SIGIR '71 Conference publication, p. 117-131. Kildall and Hunt describe how to structure a data (file) storage and retrevial system between memory and disk storage. "Heathkit" refers to a modular approach using a "kernal package" of subroutines. These were methods intended to produce multiple applications from a well-built set of components: subroutines and data structures. With these methods, Kildall built an APL interpreter and a data retreival systsem for a Burroughs B5500; apparently these were written in Algol. The latter was not a general file system, but a texted-base data system.

The summary to this paper is notible for what it suggests about Kildall's programming philosophy: "Building complex systems requires sophisicated tools. The Heathkit approach is an attempt to make it easier to program complex programs that are easy to maintain and understand. Basically, the approach will work if many systems can be designed with the same tools." He stressed that using such tools, the projects described were completed by persons "without any substantial background in systems programming".

"Algol-E: An experimental approach to the study of programming languages". Gary A Kildall, Alan B Roberts. Naval Postgrad. School. pub. March 1972, SIGCSE '72 conference papers, p. 127. Kildall and Roberts describe the Algol-E compiler written for the Burroughs B5500, constructed using XPL compiler generator system, a common software package of the era.

"Systems Languages: Management's Key to Controlled Software Evolution" by Gary Kildall. Proceedings of the 1974 Western Electronics Show and Convention (WESCON), September 1974 ("1974 WESCON Technical Papers", Volume 18, Session 19/2). In this paper, Kildall discusses how PL/M is an example of a high-level language for microprocessor development. The value of high-level languages is to ease portability, maintenance, documentation and expandability of programs. He notes "experience has shown that, for programs larger than 1000-2000 bytes, the PL/M compiler actually produces better machine level programs than hand-coded versions, [because for large amounts of code] assembly language coding becomes confused and disorganized." His example is Intel's PL/M, migrated from the 8008 to the 8080 as itself an example of portability. He also cites that PL/M code production has improved over time. "Several versions of Intel's PL/M compiler have been released since its first introduction in June of 1973" (Ver 1) for the 8008; another 8008 version (Ver 3) in Feb 1974, and the first 8080 version in March 1974. A text version of the article is at this Web link.

"High-level language simplifies microcomputer programming", by Gary A. Kildall, Naval Postgraduate School; Electronics magazine, June 27 1974, pgs 103-109. A copy of the article is here.Kildall discusses Intel's PL/M for the 8008 and 8080. This was written before CP/M was completed, as Kildall makes no mention of any floppy disk operating systems as he does in his later NCC publication in arly 1975. The earlier PL/M 8008 version was Fortran programs PLM1 and PLM2 with 8008 interpreter Interp/8. The then-recent 8080 PL/M version was programs PLM81 and PLM82, with 8080 interpreter Interp/80. An example for the 8008 version, compiled to run on the Intel MCS-8 development system (Intellec 8) or SIM-8 single-board 8008 system, is described. As with the 1975 NCC paper, Kildall does not take credit for Intel's PL/M.

"Microcomputer software design - a checkpoint". Gary A Kildall, Naval Postgraduate School. AFIPS Conference Proceedings 1975 National Computer Conference (NCC). p 99-106. In his introduction, Kildall contrasts hardware development of microprocessors as logic elements, versus software development in the minicomputer world. Kildall's bridge between these is to use cross-products which run on minis or mainframes but which test or produce code for microprocessors. This leads to a discussion of high level-languages for microprocessors, of which there are only two at the time (from an independent survey). He mentions National Semiconductor's PL/M+ for the IMP-16 and PACE microcomputers, to be available in mid-1975, as "basically compatible" with Intel's PL/M. In the rest of the article, Kildall describes Intel's PL/M complier, "available since mid-1973", with an hardware and programming example of a diver's computer for depth and time, as implemented with an 8008 and later 8080. 8080 PL/M code is shown. (He does not take credit for either PL/M or PL/M+ in this article.)

The article describes (p 102) what may be the CP/M system Kildall developed, as follows. "One such computer system, includes a floppy disk operating system, which implements a named file structure with dynamic disk allocation on multiple disks, sequential or random access, and optimal disk arrangement strategies. When combined with the system's loaders, language processors, editors, and debuggers, the resulting facility rivals that of most time-sharing services for microcomputer program development. All software modules are written in PL/M including basic file management subroutines (3K), transient console command handler (2K), and various utility programs." The language processors include a mention of BASIC with floating point, "written in PL/M (5K)".

Appopos of the National PL/M product, Kildall says (p 102) this systems software will "execute on Intel's 8008 and 8080 machines, as well as National's IMP-16 and PACE microprocessors with little modification". In the conclusion of this paper (p 103) he says "National's PL/M+... will be available in mid-1975 as an integral part of their floppy disk-based development system". I have no evidence of Kildall working for National. More info about National's compiler is at this link.

Dr. Dobb's April 1976: "First Word on a floppy-disc operating system"

By DDJ editor Jim Warren: "We have the first tidbits of information on the floppy-disc operating system to which we have alluded to in past issues...the system, called "CP/M", runs on an 8080. It is available from Digital Research [Pacific Grove CA PO box]. Its user interface is patterned after that of the DECSYSTEM-10. The file commands include RENAME, TYPE, ERASE, DIRECTORY, LOAD, and auto-load/execute facility (type the name of an object file; it will be loaded and begin execution)...An Editor is included that has somewhat the flavor of TECO. There is a PIP facility that allows easy transfer of files to and from any available device...The system is written in PL/M...The system is sufficiently modular that its designer feels he can easily modify it to operate on most floppy-disc drives and with most floppy-disc controllers."

"This system already exists and has been in use for over a year. [italics by author]...It is expected that Digital Research will offer all of the parts for an inexpensive floppy-disc system, ready to build (kit) and/or plug-in (assembled) to an IMSAI or Altair microcomputer. These "parts" consist of CP/M, the operating system; a floppy-disc controller; and floppy-disc drive(s). Pricing is still tentative, however these are the conservative estimates:
CP/M User's Manual + Editor's User's Manual + CP/M Interface Manual ...$15
Extensive Systems documentation package...$35
Formatted, verified "loaded" disc.....$20
Floppy-disc controller.....$100-$350
Floppy-disc drives....$550-$650"

Dr. Dobb's Aug 1976: "The time for Floppy's is Just About NOW!" by DDJ editor Jim Warren

...The best [floppy] system we know of...is available from Digital Systems, Livermore CA (ask for Dr. John Torode). This is the same crowd that built Gary Kildall's original floppy disk interface over two years ago. ...Dr. Kildall's fancy, DECSystem-10-like operating system - called CP/M - will run on DS's hardware. CP/M have been in use for over two years in a production and instructional environment.....Dr. Kildall's CP/M is available from Digital Research, for $35-$70 depending on the level of documentation desired. The software comes in the form of a "loaded" disk, including an editor or two, an assembler or two, a PIP, a debugger, and who knows what else (it grows from month to month).

Dr. Dobb's Nov/Dec 1976, p 51: "Upgraded CP/M floppy disc operating system now available"

Published as an information item without byline: "...Previously available only to OEM's, CP/M has been in existence for over two years in various manufacturers' products, and thus has had extensive field testing. The overall operation of CP/M closely resembles the standard features of the DEC System-10." The article describes BDOS and CCP with its commands; the system programs PIP, SUBMIT, ED, ASM, DDT, LOAD, DUMP and SYSGEN. The manuals are CP/M Features and Facilities, Editor, Assembler, Debugger, Interface Guide, and System Alteration Guide. "The works" with diskette is $70.

Published on the same page is a letter from Robert Swartz of Illinois, dated Nov 1 1976, who says he bought a disk operating system from Digital Systems and Dr. Torode. He describes it as "running for nearly a year now and have had no trouble with it".

BYTE magazine, January 1977, p 128: "Digital Systems" small ad.

The earliest magazine advertizement for CP/M, seems to be this small ad in Byte Magazine for January 1977. It reads: "Floppy disk system, completely assembled unit, $1595.00...Shugart drives and DIGITAL SYSTEMS FDC-1 controller...interface to the Altair/IMSAI bus...The powerful CP/M Disk Operating System, written by the originator of Intel's PL/M compiler, is available for only $70. Systems have been operating in the field for over two years." from "Digital Systems, 1154 Dunsmuir PL, Livermore CA".

Dr. Dobb's Feb 1978, pp 10-13; "A simple technique for static relocation of absolute machine code"

An article by by Gary Kildall in DDJ #22, Vol.3, No.2. Kildall describes how to relocate 8080 object code without referring to the source. One assembles two files to Intel HEX format (a standard option); one ORG'ed to 0000H, one ORG'ed to 0100H. An algorithm, described, looks at both files and sees where the code has bytes which are different by *one*, suggesting the reference is the upper byte of a 16-bit address. One can then add an offset to relocate the code to any other 100H ("page") boundary. Differences other than one are treated as an error. Kildall describes this with reference to CP/M, which can be "resized" to fit available memory during system generation; and DDT which is loaded to the top of available TPA memory when in use.

PL/M and related products, from Kildall/Intel or others

Further information on PL/M and related products, including PLuS PL/M compiler by Kildall for Signetics 2650PL/M for RCA COSMAC 1802, have been moved to a Web page about those PL/M and related products. - Herb, June 2018

retrospective references

Kildall's DDJ 1980 account

The most direct account of CP/M is in the article by Kildall, in Dr. Dobb's, No.41 JAN 1980, Vol.5, No.1, "The Evolution of an Industry: One Person's Viewpoint". Thanks to Emmanuel Roche for this reference, and Steve ?? discussion of it in 2009 .A text copy of the article is at this link.

Kildall indirectly dates his early CP/M work. He says that by 1973, he had provided Intel with PL/M for the 8008 (later for the 8080), as cross-compilers running on "timesharing computers". A "resident compiler would be the next step", he had proposed. But he knew that paper tape would not be a fast-enough data storage medium.

Kildall says later in the article that he became "intreigued" with floppy disks as an alternative, but could not afford one at $500, "At that time, a smallish company called Shugart Associates was in operation a few miles up the road from Intel." An IEEE Computer magazine ad of November 1973 for Shugart Associates, gives an address of "335 Soquel Way, Sunnyvale Calif." A 1977 Intel Data Book has one Intel address as "990 east arques ave"; this is 1.7 miles drive away (Google Maps). And an IEEE Computer article of June 1973 compares four floppy drive products, and describes the Shugart 900 in detail, so they were clearly available at the time and the article was likely known to Kildall.

In the biography of Kildall in "They Made America", apparently written in part from Kildall's unpublished autobiography, the author Evans states "The equipment sat in his office for a year, the software genius defeated by hardware."

In any event, he obtained a used floppy drive from Dave Scott of Shugart Associates, but failed to complete a hardware controller for it. He wrote: "Between projects, I put together first CP/M file system, designed to support a resident PL/M compiler", by using his "Interp" software simulator, "to the level of primitive disk I/O". Collectively, these references suggest that Kildall began working in 1973 on the disk I/O portions of what became CP/M, using his simulator to complete the code while "struggling" with disk hardware to run it "live".

"Shortly thereafter, in the fall of 1974," wrote Kildall, "John Torode became interested in the project. I offered as much moral support as possible while John worked through the abberations of the IBM standard to complete one of my aborted controllers. Our first controller was a beautiful rat's nest of wirewraps, boards and cables (well it was at least beautiful to us!) which, by good fortune often performed seeks, reads and writes just as requested." He describes loading the paper tape of CP/M and then, "to our amazement, the disk system went through its initialization and printed the CP/M prompt at the Teletype". After a "few nervous tests", Kildall says he and Torode "retired for the evening to take on the easier task of emptying a jug of not so good red wine while reconstructing battles, and speculating on the future of our new software tool". Kildall does not date this event.

Kildall continued: "In the months that followed, CP/M evolved rather slowly. Intel was experiencing enormous growth, and all software development was halted while new management structures were instituted. Intel expressed no interest in CP/M, nor in continuing any resident compiler work. Nearly two years passed before Intel again took interest in resident software tools, with their introduction of the ISIS operating system and later, the resident PL/M-80 compiler." For reference, Intel's 1977 Data Catalog includes descriptions of ISIS-I, ISIS-II and a resident PL/M compiler (associated with ISIS-II) on an MDS Multibus-based system. That year, less two years, suggests 1975 or earlier for when Intel "expressed no interest" in CP/M. (I'd appreciate references for the introduction of 8080-resident PL/M and of ISIS. - Herb]

"Meanwhile," writes Kildall, "John Torode redesigned and refined our original controller and produced his first complete computer system, marketed under his company name, Digital Systems (which later became Digital Microsystems). The first commercial licensing of CP/M took place in 1975 [my emphasis] with contracts between Digital Systems and Omron of America for use in their intelligent terminal, and with Lawrence Livermore [National] Laboratories where CP/M was used to monitor programs in the Octopus network." (In a personal discussion in 2008, Dr. Torode had a slightly different description of his work with Kildall.)

Kildall wrote: "Little attention was paid to CP/M for about a year. In my spare time, I worked to improve overall facilities, and added an editor, assembler, and debugger which were predecessors of the current ED, ASM, and DDT programs. By this time, CP/M has been adapted for 4 different controllers."

Kildall goes on to describe work with IMSAI in 1976 for CP/M V1.3; Kildall credits his IMSAI work as "evolving" the notion of a separate BIOS. Discussions "at the same time" with Jim Warren, the DDJ editor, led to the introduction of CP/M 1.3 for sale "to the general public" by "a new company called Digital Research". Kildall's work with IMSAI is discussed elsewhere by me.

Kildall's 1981 BYTE account

Kildall wrote a BYTE article in June 1981 titled, "CP/M: A Family of 8-and 16-Bit Operating Systems". A copy of the article is or was available at this DRI-supporting Web site.

In the article, he provided a history from the early 1970's through 1981 for his language and operating system developments and products, and their historic predecessors. In that context, for instance, he says that "MAA" (his consulting company) wrote PL/M for Intel. "PL/M", he describes, "is a refinement of the XPL compiler-writing language which is, in turn, a language with elements from Burroughs Corporation's ALGOL and the full set of PL/I." (Kildall wrote an ALGOL-E compiler for teaching use in 1971: his students later wrote the ALGOL-M compiler for CP/M.) "The first substantial program written by MAA using PL/M was a paper-tape editor for the 8008 microprocessor, which later became the CP/M program editor, called ED."

He notes that MAA proposed to Intel a "CP/M (Control Program for Microcomputers), which would form the basis for resident PL/M programming.... But the use of PL/M on larger timesharing computers was considered sufficient, and the CP/M idea was rejected. CP/M was, however, completed by MAA in 1974." The article also describes MP/M, CP/NET, his PL/I. The 1981 article discusses 16-bit processors, which Kildall notably calls "already outmoded, and all serious manufacturers are pushing 32-bit machines". CP/M-86 and MP/M-86 are barely mentioned. The IBM PC was announced in 1981.

"Digital Dialogue" internal newsletter of DRI, August 1982, Volume 1 #1.

In the newsletter, Gary Kildall is listed as President of Digital Research, and all employees are listed by title and phone extension. Otherwise, there is one article titled "Rapid Expansion marks DRI history". This article is later copied at the "digitalresearch.biz" Web site, which hosts photos and documents from the "Digital Research - Sept 24 1999, 25 year reunion". The PDF "reunion book" has a copy of the article. COpies of Digital Dialogue might be found on the Web in PDF form: I obtained a copy in 2009 from this CP/M archive site. A text copy is available here.

Quote - According to Gary, it all really began back in 1974 when that first version of CP/M was developed and debugged....Gary Kildall worked in his backyard playhouse with the hummingbird feeders outside the door, thinking and tinkering with his first version of CP/M - and at just the right time he got a little help from a friend. "John Torode, president of Digital Microsystems, came to my aid with a home-built disk drive controller, which we wired up between my Intellec-8 development system hardware and an early flexible disk drive I'd been given by Dave Scott of Shugart Associates. We loaded up the first version of CP/M from a paper tape reader into the Intellec memory. With the first CP/M prompt appearing on my used Teletype in 1974, we were both aware that a new computer generation was in progress," Gary recalls. --end quote--

The company filed a business name "Intergalactic" Digital Research in June 1976, and was incorporated in August 1977. "Intergalactic" was dropped when an early company called Digital Research cease business. The rest of the article confirms information from Kildall's DDJ 1980 account, with additional details about employees, locations, and products. There's no dollar income figure, but in the summer of 1982 DRI had 200 employees.

"Programmers At Work" interview of Kildall

A mid-1980's Kildall interview was found on the Web archive in Oct 2007 at this link. The interviews were published in the book: "Programmers at Work: Interviews" By Susan M. Lammers, Published 1986, Microsoft Press, 392 pages. ISBN 0914845713. The interview was probably in 1985.

This is a link to a copy of the interview. The part most relevant to early CP/M, is when Kildall says he was "trying to get PL/M to run resident on the 8080 microprocessor, and I had to write an interface to communicate with a disk drive. It turned out that the operating system, which was called CP/M for Control Program for Micros, was useful too, fortunately....I didn't know CP/M would be such a hit, but it was very clear to me that floppy disks would be. I had been working with paper tapes for a year and a half. A floppy-disk drive was $500 and a paper-tape reader with a fancy punch was over $2,000. Just by looking at the cost comparision of the two drives, I realized the floppy disk would be a commercial success."

"Fire in the Valley" and "Collegial Entrepreneurship" references

Fire in the Valley was first published in 1984 (ISBN: 0881341215) by Osborne/McGraw-Hill. Written by Paul Freiberger and Michael Swane, it's a compilation of early personal computing history with many first-person accounts. References notable to Kildall and CP/M are excerpted below. Unfortunately, the book's accounts jump back and forth in time, and so I'm obliged to quote out of page order to restore a chronological sequence. References below are from the first edition; an "updated edition" (ISBN: 0071358927) or "collector's edition" with CD (ISBN: 0071358951) was apparently published after year 2000.

The book's earliest mention of Kildall (p 136 f) describes Kildall's early work with the 4004 and, starting in 1973, with Intel as a consultant. "Soon he was dabbling with Intel's first 8-bit microprocessor, the 8008...In a few months he had created a language called PL/M, a version of a mainframe language called PL/I and significantly more elaborate than BASIC." Kildall received an Intellec-8 from Intel as a result, which was later upgraded from an 8008 to an 8080. "Kildall set out to get a disk drive and did a little programming in exchange for one from Shugart....Kildall tried to design [a floppy] controller several times. He also sought to create an interface [for]...a cassette recorder. The project failed....Finally, at the end of 1973, Kildall approached John Torode, a friend of his from the University of Washington...Torode got the drive to work."

"Meanwhile, Kildall polished the software. At one point late in 1973, during his months of frustration with the disk drive, Kildall had written a simple operating system in his PL/M language. It took a few weeks to complete, and he called it CP/M, for Control Program/Monitor."

Given the above, it appears that the first actual operation of CP/M was sometime after late 1973. But Kildall himself says in 1980 that Torode only entered the picture "in the fall of 1974" to complete the hardware controller: Kildall did write software earlier but could not run the diskette file I/O code until the disk hardware was operational.

Swane's describes (p. 138) that some of CP/M's "enhancements" and "first commercial tests" were done for Ben Cooper's "Computer Cast", a coin-operated machine to cast horoscopes. Systems tested in San Francisco did poorly, "the machine was a failure". But the text explains that what was actually tested and developed were what became CP/M's editor, assembler, and debugger; as well as a BASIC interpreter "that allowed him to write the programs for the astrology machine". In my (Herb Johnson's) opinion, this device was not a CP/M implementation (it was ROM-based), but in effect a test bed for some later CP/M tools. No date is given for this work or when the machines were in use.

(p. 58) "by mid-1974 Torode and Kildall had assembled a microcomputer and a disk operating system of sorts....They sold two machines to a San Francisco Bay Area computer terminal company called Omron, but sold only a few others before the Altair announcement. They then apparently pursued their interests independently. Torode built computers under the name Digital Systems and later Digital Microsystems, and Kildall wrote software as Intergalactic Digital Research and later Digital Research." The MITS Altair 8800 was announced in Popular Electronics in January 1975.

(p. 139) "At first the Kildall's called their company Intergalactic Digital Research...Digital Research's earliest customers received some startling bargains. For instance, Thomas Lafleur [later of GNAT Computers]..made one of the first corporate purchases of CP/M...for $90.."

(p 69) "IMSAI bought an operating system called CP/M from...Gary Kildall, the same man who had sold computers with John Torode to Omron. CP/M was brand new. Kildall had given [Rob] Barnaby [of IMSAI] the third copy in existence. [IMSAI marketing director Seymour] Rubenstein negotiated with Kildall and his partner and lawyer, Jerry Davis, and closed the deal for a flat $25,000." Other references in the text note that Rubenstein joined IMSAI in February 1977, and "when Rubenstein arrived, Barnaby was negotiating two software contracts with people from the Naval Postgraduate School..", a likely reference to Kildall and Gordon Eubanks.

"Inside Intel" by Tim Jackson, 1997

"Gary Kildall and Collegial Entrepreneurship", Dr. Dobb's, 1997

"Dr. Dobb's Special Report" by Michael Swaine in Spring 1997, likely a Web based column (?) discusses Kildall's history. A copy of the article was available on a DRI supporting site. The DDJ Web also site has a copy.. The article covers much the same ground as Swaine's "Fire in The Valley". The following is quoted from the article.

"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... he began working there as a consultant on his one free day a week. He spent months programming the 4004... 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... he wrote programs to simulate the microprocessor on the "big" minicomputer....[but] 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."

"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. 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."

The article goes on to describe Kildall's work with Torode, the "Astrology Machine", IMSAI and others. I am not confident that the specific years mentioned for various events are accurate. To me they appear about a year early in many cases.

Gordon Eubanks' account for Comuputerworld

Gordon Eubanks, a master's student of Kildall and a Naval officer in the 1970's, started Compiler Systems from his CBASIC compiler. He sold that company to Digital Research, later leaving it and buying Symmantec. That company expaned and bought several other companies. In November 2000, Computerworld magazine sponsored a "Gordon Eubanks Oral History" interview, for their Computerworld Honors Program. It was done in Cupertino, California on November 8, 2000 by Daniel S. Morrow (DSM). As of 2008 a copy was on this Web site.

Eubanks says he first met Kildall in 1975 when he came to the Naval Postgraduate School as a Naval officer. Quoting Eubanks: "When I first met Gary at the postgraduate school and he was my thesis adviser, he was mulling over what to do with CPM. Just to be clear, CPM was something that he wrote to demonstrate that these microcomputers could be general purpose computers. He wrote it to just show the value of the technology. Al Shugart at Seagate donated a couple of disk drives. Somebody wrote a disk drive controller card that was wire round. There were like three of them in existence. He had an Intel blue box, which just had the CPU in it. He had jerry-rigged this system to run CPM on it. There were like two or three of these systems in existence in the world. There was really weren't even prints to show how this disk controller worked. I don't know if it could ever have been reproduced. Who knows what would have happened if the thing had failed early on and hadn't worked."

I provide more details of the Kildall portion of the interview in this document.

"They Made America" chapter on Kildall, 2004 and later

They Made America was a book written by Sir Harold Evans, first published in by Back Bay Books in 2004, ISBN 0-316-27766-5. Each chapter describes an American which Evans and his collaborators believe made major contributions to the United States. Evans gives credit to Kildall for developing early personal computing, including CP/M and how it influenced MS-DOS. Evans says his Kildall's quotes and material were based on Kildall's unpublished autobiography. Here's a text of the (2004?) chapter, for the period before and after CP/M was developed. Thanks to Emmanuel Roche for typing this material.

A 2010 obituary for Kathryn Strutynski, the 4th employee of Kildall's DRI, points out she was a contributor and project leader for the CP/M product line. Decades later, she contributed to Sir Harold Evans' paperback update of his book "They Made America" in 2006. Kathryn died April 9, 2010. The obituary was published June 19th in the Monterey Herald in California. Thanks to a likely anonomous post in comp.os.cpm for Sept 10 2010, which carried the link and the text of the obituary.

Some additional notes from Kathy Strutynski are on the Naval Postgraduate School Web site. A Nov 4 1986 InfoWorld article refers to her as "the product marketing manager for Concurrent PC-DOS".

other Kildall history as recorded in the 1990's

Additional references to Kildall's history, provided by Charlie Garthwaite:
An 2007 video interview by Robert Scoble of Tom Rolander, an early DRI employee with some first-hand knowledge of the IBM "event":
a copy of the above interview:
A Business Week story about They Made America and the IBM "event":
A 1995 three-installment YouTube copy of the Computer Chronicles of the biography and history of Gary Kildall: part 1 - part 2 - part 3. Kildall hosted this syndicated PBS series for six years until his death.

MS-DOS as "derived" from CP/M?

It's been repeatedly argued that the original MS-DOS for the IBM PC, bought by Microsoft from Seattle Computer Products and written originally by Tim Paterson, was "derived" in some way from Digital Research's CP/M 2.2. The arguement is how the "derivation" occurred. In July 2007, a Seattle court looked at this issue as a result of Paterson's lawsuit against author Sir Harold Evans who argued as much in his book, "They Made America", which featured a chapter on Gary Kildall which discussed the issue. This report of the judge's ruling by Andrew Orlowski in the UK Register, says that the judge agrees that functions of MS-DOS were copied from corresponding CP/M functions, and that Evan's claims were largely factual and without malice.

Dr. John Torode and his associates

A brief biography of Dr. John Torode is on the DRI history Web page. His links to CP/M are that he completed (or replaced) Kildall's floppy controller for Kildall's first CP/M implementation; and he was the first "licensee" and seller of CP/M.

Torode published papers with Theodore Kehl and Lawrence Dunkel; they also published works on digital design. Dr. Theodore Kehl was a 1961 Ph.D from the University of Wisconsin, Madison, WI and was a professor of physiology and biophysics at the U of Wash. He may have been a founding member of the U of Wash. Computer Science Department in the mid-1960's. In 1974 Kehl was a Computer Science associate professor at the University of Washington with Dr. Torode. Lawrence Dunkel was a member of the Physiology and Biophysics Dept. in 1974. Kehl and Dunkel were digital designers and programmers. Subsequently, Dr. Kehl has several US and European patents in his name (some with David N. Cutler), assigned to DEC and Microsoft, dating from the 1990's and with a 2005 date.

"The Logic Machine: A modular computer design system". John Q Torode and Theodore H Kehl; IEEE Transactions on Computers, Vol C-23, no. 11, November 1974. Written in Nov 1973. In the era, computers and digital logic were often designed as a collection of "logic modules". There were software tools, run on mainframes, to facilitate development. Also, computer scientists studied the principles behind these modules and how to use them. Torode and Kehl, in this article, describe the modules behind their microprogrammed computer design: a control processor, a memory manager, a floating point unit, a hard disk management unit, and other "functional units". They refer to actual hardware designs which were implemented, namely a display terminal and a floating point processor.

"Design Automation for Custom Hardware in Computer Research", by Theodore H Kehl, Christine Moss, Lawrence Dunkel. IEEE Transactions on Education, August 1974. Written in Oct 1973, this paper describes a semi-automated hardware wirewrap system designed and at use at the University of Washington. Combined with CAD software, "this system allows graduate students and faculty [to] experiment with new computer devices not available in the marketplace". This system was used to build the display terminal and floating point processor described in the "Logic Machine" article above.

"Simplified Floppy-Disk Controller for Microcomputers" by Theodore H Kehl, Lawrence Dunkel. Computer design, June 1976, p 91-7 Absent a description of Torode's or Kildall's floppy controller, this article by Torode's colleagues which describes a controller design and operation may be informative. The article describes a simplified version of the IBM 3741 format (identical to the common "SSSD" 8-inch format), which reduces hardware complexity, improves error recovery, and increases data capacity. Capacity is increased by using larger sectors (8 vs. 26), smaller or no gaps, and reduced redundancy per sector. The article implies use of the Shugart 901 diskette with 32 hard sector holes. The controller design consists of several 74XXX series chips: 8-bit multiplexers, adder, and shift registers. There is no schematic but there is a block diagram. The checksum is a simple 16-bit sum and not a CRC. Flowcharts show general read/write operations and error recovery.

Update: My thanks to Charles Garthwaite, who contacted me in Feb 2010, provided further references, corrections and comments. He writes: "As a graduate student contemporary of Gary Kildall's at UoWA CSci and Ph.D. advised by Ted Kehl, let me say how great to read your "30 Years of CP/M" presentation. My associates in Kehl's hardware lab were John Torode & Ken Burkhardt, who went on to co-found Dialogic, a PC-based telephony firm later purchased & subsequently sold by Intel. The hardware lab was physically located in the Medical School Physiology & Biophysics Dept. where Ted Kehl held a joint appointment. So I only know by reputation Gary and Rolander, who was in the EE Dept. which was then quite separate from CSci..Definitely were interesting times! Thanks for documenting them." Charlie discusses Dr. Kehl's hardware lab and the "logic machines" of Torode and Kehl on this linked Web page.

Digital Systems's FDC controller products

See this Web page for descriptions and documents about Torode's floppy controller products.

2008 discussion with Dr. John Torode

In February 2008, on a Web page then under development about Dr. Torode's Digital Systems products, I referred to Kildall's published statements that Kildall's floppy controller was "completed" by Torode. In personal discussion with Dr. John Torode in March 2008, he had this to say: "You state that I got kildall's floppy controller working, but my memory is that I gave up quickly and produced a new design (based on my thesis, as you say) and that was the only floppy controller that we actually got to work." He also noted: "Gary and I made the first software/hardware (complete system) sales jointly under my company (because I had one!) My company, digital microsystems, was started (in seattle) while i was in grad school as digital systems, in 1967. That name was taken in california so we changed to digital microsystems in some year i forget."

Lawrence Livermore Labs and CP/M?

In February 2008, I corresponded with Jeffery W. Shook about the use of CP/M by Lawrence Livermore National Labs (LLL or LLNL). Jeff had researched this out over the prior few years, but had found no clear mention of "CP/M" in the Lab's publications. He kindly provided me with his notes. Those notes and our discussion are on this Web page.

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Copyright © 2018 Herb Johnson