back to article PC pioneer Gary Kildall's unpublished memoir revealed

The Computer History Museum has revealed part of an unpublished memoir by Gary Kildall, a programmer and entrepreneur who made critical contributions to the personal computer industry in its formative years. Kildall died aged just 52, in 1994, but in his short life he earned fame for developing CP/M, an operating system that …

  1. Anonymous Coward
    Gates Horns

    CP/M and BIOS inventor adds to story how Microsoft's IBM deal shaped the PC forever

    CP/M and BIOS inventor adds to story how Microsoft's IBM deal fucked the PC forever


  2. Oengus


    I still have an Apple ][plus and I even have the CP/M card (probably not the Microsoft one) similar to the one referred to in the story. I can still remember running CP/M in my formative years.

    I think this will make interesting reading.

  3. wolfetone Silver badge

    I have to wonder why there hasn't been a biography written about him? There's a lot about the bloke that we don't know, this article and memoir shows that.

    1. Tchou

      Like when in court with Bill Gates over DOS, Gary claiming it was outright theft of CP/M, he got a PC running DOS, typed in a hidden command and DOS displayed the CP/M copyright.

      1. wolfetone Silver badge

        See, I didn't know that.

        1. Tchou
          Thumb Up

          "possible homicide"

          "After 20mn into the bar, witnesses turned to him and saw he was on the ground"

          Police : "That version isn't going to hold for long"

  4. kmac499

    Ahh Memories

    Yes back in the neolithic I ran CP\M on an industrial placement. The 'Office suite was the WordStar,DataStar,Calclstar suite which transitioned across to MS-DOS.

    In a straight choice (excluding the IBM effect) I would probably have gone for CP\M as it seemed to offer a more developed growth path to the 16bit world, multi-users and the GEM GUI.

    1. Down not across

      Re: Ahh Memories

      In a straight choice (excluding the IBM effect) I would probably have gone for CP\M as it seemed to offer a more developed growth path to the 16bit world, multi-users and the GEM GUI.

      For multi-user you need MP/M. Worked rather well actually. The bank switching that enabled users to have reasonable amount of memory each, was later available in the single-user CP/M 3.0 which therefore could address more than 64KB RAM.

  5. Daniel von Asmuth


    The CP/M consisted of three parts: the BIOS, which was mainly device drivers, the BDOS, which was mainly disc management, and CCP, which was the command interpreter. That part was overlaid when you loaded an application and reloaded when the application finished.

    PC-DOS and MS-DOS kept the same architecture, but put the BIOS part into ROM, and the others were loaded from floppy disc. The BIOS acted as an abstraction layer: it had to be rewritten for every slightly different model of PC or compatible, while the DOS parts on floppy were generic.

    Later you had MSX-DOS, an odd hybrid of MS-DOS and CP/M.

  6. AustinTX

    Lobo Max-80

    CP\M on a Lobo Systems Max-80 was a lot of fun. But the Max-80 also ran LDOS, which had the lion's share of available software. I remember reading about the BIOS debate in computer magazines. I think they were calling it something else still. The objection was that this in-between layer would double execution times because it had to make that standard call that made the proprietary call. Unthinkable! PCs were so slow back then that it was worth it to just make a custom version of the OS for each model.

  7. Mr Dogshit

    "to pen" is not a verb

    Repeat after me: "to pen" is not a verb

    1. Warm Braw

      Re: "to pen" is not a verb

      Gramfrags get newed thru usaging.

    2. wolfetone Silver badge

      Re: "to pen" is not a verb

      Typikal grammor natsees, cumin on foreums, dicktating our werds. Didn even writed fool stops in there writings.

    3. Destroy All Monsters Silver badge
      Thumb Down

      Re: "to pen" is not a verb

      "to pen" is not a verb

      Go back to Pokémon Go, noob:

      to pen (formal): to write something: "She penned a note of thanks to her hostess."

    4. Chemist

      Re: "to pen" is not a verb

      "Repeat after me: "to pen" is not a verb"

      What !

      As others have said to pen an essay etc. is perfectly correct usage and indeed what would farmers do to enclose animals - " the shepherd penned his sheep" .

      1. billat29

        Re: "to pen" is not a verb

        My American friends would say; "There ain't no noun that can't be verbed".

        1. hplasm

          Re: "to pen" is not a verb

          Verbing nouns weirds language!

        2. Anonymous Coward

          Re: "to pen" is not a verb

          Your American friends deserve a good footing.

    5. Tchou
      Paris Hilton

      Re: "to pen" is not a verb

      I nonetheless penned her quite hard.

  8. Colin Bull 1

    The next chapter

    When I got to page 78 I kept hitting the page down key because it was keen to read the next episode.

    I hope the children release that soon

  9. PhilipN Silver badge


    Hats off to the guy.

    And to Phoenix for having the balls to reverse engineer IBM's BIOS which I believe is an equally significant move in the history of computing.

    I do not remember where I read the story long ago but I recall Phoenix had 2 sets of coders incommunicado in separate rooms. The first set looked at each line of code and shouted to an intermediary what it did, who then told the second set. They then wrote new code to perform the same action.

    The pros will no doubt correct my phraseology and amplify the tale.

    1. Anonymous Coward
      Anonymous Coward

      Re: BIOS

      It is doubtful that this kind of "clean-room implementation" follows either the spirit or the letter of the law. One might as well have the cleaning lady (oops, "room rehabilitation engineer") drop by every 2 hours...

      Did it come from this reimagining?

    2. Wensleydale Cheese

      Re: BIOS

      "And to Phoenix for having the balls to reverse engineer IBM's BIOS..."

      Clean room implementation of the IBM BIOS

    3. TonyJ

      Re: BIOS

      "...Hats off to the guy.

      And to Phoenix .."

      Y'know, I always thought Compaq were the ones who reverse engineered the IBM BIOS?

      <EDIT> I should've read further down - particularly Wenselydales link.

  10. hypernovasoftware

    I thought it was pretty cool to read something straight from Gary's pen.

    He was an incredible guy and I am still saddened by his too early passing.

  11. Mark Morgan Lloyd
    Thumb Up

    Interesting indeed

    That /is/ going to be an interesting read. Kildall did some good work when youger, but more than anything else any insights on how DR became such a pain to deal with in the mid 80s and how they lost their way completely before being bought by Novell will be very welcome.

    1. Richard Plinston

      Re: Interesting indeed

      > how they lost their way completely

      It may well be that 'your way' was different from 'their way', but DRI were not 'lost'.

      DRI had released MP/M multiuser/multitasking system by 1978, networking by 1979 and went on to produce Concurrent-CP/M and Concurrent-DOS, multitasking with virtual screens, which were demonstrated prior to the toy MS-DOS being released as version 2 that added hard disk support (which CP/M had in 1976).

      DOS+, DR-DOS 3.x, and especially DR-DOS 5 and 6 drove MS to improve their products, though it took them 20 months to catch up.

  12. tskears

    Digital Research DOS

    DR-DOS was always one (sometimes two) steps ahead of Microsoft. I ran it up to version 6.0.

    1. Dabooka

      Re: Digital Research DOS

      I remember that too, following on from cp/m on various Amstrads (6128 and PPC1512?). My step father always seemed to come home with new OSs, everything from DR/MS DOS, GEM, Win 3, OS2 including Warp etc.

      Every other month the magazines seemed to review the latest 'must have' OS. I must confess to loving Warp at the time, although the reasons why escape me today

      1. MJI Silver badge

        Re: Digital Research DOS


  13. Chris Gray 1
    Thumb Up

    happy memories

    CP/M may not have been much by today's standards, but it did the job just fine, and brought early computers into businesses, schools and homes. I had it on a Godbout CompuPro system.

    I remember seeing MP/M (multitasking CP/M!!!) running on a system in a store downtown - impressive!

    I wrote a *lot* of software on my CP/M system. It was an S-100 box, and I had bought a couple of graphics cards for it, plus expansion memory. So, I had my Draco compiler and utilities, my Ded editor, my Explore D&D-ish system (never really released), my RAM disk cache (hooks in BIOS) etc.

    Things were so much simpler back then!

    1. Tchou

      Re: happy memories

      "Things were so much simpler back then!"

      Simpler and yet not simplistic. It was as simple (or complex) as it needed to be.

      However things are so much uselessly complex these days!

    2. Down not across

      Re: happy memories

      I wrote a *lot* of software on my CP/M system. It was an S-100 box, and I had bought a couple of graphics cards for it, plus expansion memory. So, I had my Draco compiler and utilities, my Ded editor, my Explore D&D-ish system (never really released), my RAM disk cache (hooks in BIOS) etc.

      Things were so much simpler back then!

      They were. That reminds me of when I wanted to get 'normal' 7-bit ASCII (as opposed to some characters replaced by local language variants) on my Kaypro, I dumped the character ROM, edited the contents which I then burned into EPROM. I then proceeded to solder two EPROMS (my modified one and copy of the original) together except for chip select which I wired into a SPDT switch.

      Instant switching between real and localised ASCII.

  14. Tom 7

    I still want a teletype!

    I did spend some time trying to convert an IBM golfball typewriter to work on my MK14 but then got a Superbrain with CP/M and a C compiler on it. Whoo hoo!

    ISTR using CP/M-86 on the first IBM PCs we had at work and then we moved to DOS for some reason.

    Cheers Gary Kildall may your memory never be zero'd.

  15. Mike 16

    Back when BIOS was actually useful

    As hard as folks might find it to believe today, the BIOS on a typical CP/M machine actually worked, to provide a usable hardware abstraction layer. As opposed to the PC BIOS which was barely able to function at all outside of booting the disk, and was pig-slow to boot (er... "as well"). So applications on the PC/QDOS platform typically had to include their own I/O code (especially for video), and after Flight Simulator became the de facto acceptance test for "PC Compatible", the end was near for the sort of "Compatible, but better" machines that had flowered under CP/M (without requiring that developers write a separate version for every precious snowflake of mutant hardware. BIOS took care of that).

    Of course, one result of this "must be bit-for-bit and bug-for-bug identical to a PC" situation was the rise of the clones. No point making things better, just make them cheaper. On the other, other, hand I can't help but feel that a lot of interesting ideas from the 60s/70s took until this millenium to make it to the desktop in such an environment.

    1. PT

      Re: Back when BIOS was actually useful

      I wrote a CP/M BIOS at least three times, and it always contained quite a lot of I/O code, including video unless it was just talking serial to a terminal. It had to do all the low level disk control. The example BIOS in the CP/M documentation was just a bare bones guide, capable of serial IO but not disk IO. That you had to do yourself.

  16. Anonymous Coward
    Anonymous Coward

    Other Great Men......

    Gary Kildall was a visionary and a notable figure in the early days of "microcomputers". I owned an Osborne 01. Thanks to the fact that many software companies were able to port their CP/M applications almost "as-is" to DOS 1.0, the Osborne was useful until around 1987. dBASE II and Wordstar content could be written on the Osborne, then copied to a DOS formatted floppy on the Osborne (using MediaMaster), and then used on a PC.

    Other notable figures from the CP/M era also need some praise. Wayne Ratcliff wrote dBase II in his spare time, and created something infinitely better than MBASIC (or even CBASIC). Thank goodness Leor Zolman wrote BDS C and got people like me off 8080/Z80 assembler. These guys are never mentioned today.....they need some long overdue praise......along with Gary Kildall who made it all possible.

  17. Tiffy_S45


    Irecall that if you accessed an empty drive (Dir a:, say) then CP/M would hang. There was no recovery. A patch was published in a computer magazine which worked but Digital Research refused to implement it. It is no wonder that DR did not succeed with this head-in-the-sand arrogance.

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