back to article Proprietary OS source code LEAKED to web – from 40 years ago

Forty years after Gary Kildall released the first version of CP/M, the Computer History Museum in Mountain View, California has made the source code to several versions of the landmark eight-bit OS available as a free download from its website. The code, which is written in a combination of assembly language and Kildall's …

  1. Alain

    Concurrent CP/M

    I have used CP/M-based 8080 boxes with 8 inch floppy disks to teach Cobol programming in the early 80s (so yes, I'm a criminal according to Dijkstra). Nice memories. I liked it. It was compact, simple and elegant, with these fancy command names... isn't "PIP" sexier than "COPY"?

    On the other hand its descendant Concurrent CP/M 86 was my first experience of a real multi-tasking, multi-session O/S with screen flipping when only dirty hacks were used to add some very primitive multi-tasking for non-interactive processing to MS-DOS. It was a great O/S well ahead of its time. Too bad it never picked up.

  2. Christian Berger

    Now compare that to modern mobile OSes

    Porting Android to another mobile device is rather hard. There is no BIOS or anything like it. Even different displays on an otherwise identical system mean completely new system images.

    This is why, once the manufacturer stops supporting the system, you won't get any updates.

    1. Destroy All Monsters Silver badge
      Paris Hilton

      Re: Now compare that to modern mobile OSes

      But this is not a "mobile OS", it's made for things that today would be lower than washing machine controllers. Yeah, there is no standard for hardware on mobiles (nor on immobiles, for that matter), but so what?

      1. Christian Berger

        Re: Now compare that to modern mobile OSes

        Actually there is a standard for desktop PCs and laptops. It used to be called the "IBM-PC" and has now evolved into something, that's honestly a big mess, but it means you easily get any operating system to run on every PC. At least basic things like hard disk access, USB, hardware enumeration, keyboard, display and mouse work out of the box, on any PC.

        Also what is the amount of features you actually need on a mobile OS? You need primitive multitasking (cooperative multitasking would be enough), you need a TCP/IP stack and a web browser, the later being probably the most complex part of it. Ideally you also have a file system. The rest is overhead because of bad software design.

    2. donguevas

      Re: Now compare that to modern mobile OSes

      Do you sleep with your iphone in the front of the back of your underwear?

      Your post has virtually nothing to do with the article.

      My HP Touchpad has been running Android fine for almost three years now. And you have conveniently left out CyanogenMod.

  3. saundby
    Thumb Up

    I'm still using CP/M around here. An Ampro Little Board Plus SCSI with 88MB of hard disk and an Osborne 1 with all the extras (video upgrade, disk upgrades, etc.) are my most-used systems. But I've also got Big Board I and II systems and several Kaypros plus a homebrew.

    CP/M calms me when all the 'modern' OSes tick me off. ;)

    1. Neil Barnes Silver badge

      I'm using it to develop z80 code for embedded robotic applications... but I run it in an emulator on a 686 machine until the code actually hits the metal!

    2. osdex

      The decline of reliability

      +1 for the Osborne 1! I found a mint condition one at a garage sale recently for $20, that included all the original software, manuals, cables, keyboard overlays, sales receipt, and an unopened pearl programming package. This computer boots fast, is built like a tank, and everything is straight forward and easy. All those flimsy floppy discs it came with still work great and have accurately stored their "volatile" information.

      What are they doing these days, except making next year's garbage? When modern computers can't even carry out basic tasks without freezing up or blowing a power supply, it should drive these companies to shame. This 32 year old Osborne is more reliable than all of them put together. The funny thing is, I found a Wordstar document on one of the discs, and in it the author said they were "using the ancient Osborne to write, because my new computer is broken."

      That says it all.

  4. Destroy All Monsters Silver badge

    Intellectual Property Fetishism of the Worst Sort

    Note, however, that this source code release does not mean CP/M is open source. The code is being offered for educational purposes only and no commercial use is allowed.

    Yeah, well no, successors of Gary, you ain't gonna conquer the world with that anymore and bring in BILLIONS; give it up.

    1. hammarbtyp Silver badge

      Re: Intellectual Property Fetishism of the Worst Sort

      Yeah, has anyone told Microsoft...

  5. Dylbot

    Hah, I didn't know that Intel 8080 web emulator existed. Time to spend the working day playing Zork.

    1. Ian 55

      Interpreters for Infocom games run on all sorts of kit...

  6. Anonymous Coward
    Anonymous Coward

    "From 40 years ago"????

    That has to be a mistake. If it were true, that would make my age be at least.... oh cr*p, how did that happen!!

    1. Neil Barnes Silver badge

      Re: "From 40 years ago"????

      Yeah, happened to me too. Damn.

      Have a thumb for correct use of subjunctive mood.

  7. Anonymous Coward
    Anonymous Coward

    Microsoft bought a CP/M lookalike called Q-DOS and licensed a reworked version of it to Big Blue

    There's a lot more to it than that. Bill Gate's had insider information from his Mum (who was an attorney at IBM) that Big Blue were struggling to reach an agreement to use CP/M. He then offered to license a crude CP/M clone called 86-DOS to IBM by pretending it was a MicroSoft product. It was only when IBM expressed interest that he went out and bought the rights to it.

  8. Nigel Whitfield.

    Fond memories - and hangovers

    One of the first computers I used, and on which I learned to do many things, was an RML 380Z, with CP/M 1.4B, and I've played with systems running CP/M86 as well as MP/M later on. Happy days.

    And, though the OS itself may be mostly forgotten, it's left us with at least one enduring legacy - those 8.3 file names, and the horrible kludges still found to allow long file names to coexist with them, even in modern kit.

    No, it may not have been the first OS to use such a naming convention, but in maintaining compatibility with that that aspect of CP/M in MS-DOS, it's surely endured far longer than it would have done.

  9. Chris Parsons Bronze badge

    Been there, done that

    Writing modifications to and hooks to allow a simple menu system. What fun it was then, C++ is very boring in comparison.

  10. Nugry Horace

    Source code for later versions of CP/M can also be found at

  11. Gronk

    Wasn't it Caldera that released the source code for CP/M several years ago?

    1. Ian 55

      My copy of the source code is so old I can't find it on the current hard drives, so probably.

  12. David Given

    Well worth looking at

    CP/M is a surprisingly decent operating system --- it's a miracle of minimalism: the absolute smallest number of features required to do a decent abstraction over the hardware, and not a single one more.

    On CP/M 2, the OS proper, the BDOS, was 3kB, and provided some I/O streams, a filesystem, and... nothing else (see The command shell, the CCP, was another 2kB and could be overwritten if applications needed the RAM. These talked to the underlying hardware via the BIOS, typically another 2kB. On a 64kB system this meant apps got about 59kB of available RAM.

    And these modules all talked to each other via standard, platform-independent interfaces. The CCP and BDOS supplied in binary form by Digital Research; the BIOS you could write yourself (and they provided all the tooling, docs and a sample BIOS for you). The BIOS interface was ludicrously tiny (see and porting was straightforward, particularly as the hardware requirements were so minimal --- you didn't even need interrupts!

    It's worth playing with. There's still a wealth of ultra-minimal software out there, including actual C compilers (provided you like K&R). You can actually get proper work done on it, including internet access.

    The later versions supported bank switching, network file systems, multiple concurrent users (yes, with time slicing!) and stuff like that, but to my mind they don't have the beautiful simplicity of CP/M 2.

    1. HelpfulJohn Bronze badge

      Re: Well worth looking at

      Just a stray, random, cosmic-ray inspired thought but would CP/M run Raspberry Pi's? Not run on, but run as the main and only OS.

      Can CP/M do HDMI, USB and all the other clutter a 21st C. machine seems to need?

      Have I just found myself a hobby?

  13. Bitbeisser

    What is the news here, the source code is now for years already available at

    for more than a decade!!!!!

    1. PeteA

      Lazy journalism

      The file "origin.txt" includes the following text:


      by Gaby Chaudry

      downloaded 25 June 2014

      The link takes you to "The Unofficial CP/M Website" who

      1. Are the true source of the material.

      2. Made it publicly available in in 2002.

      3. Have more versions available, e.g. the canonical 2.2.

      4. Most importantly, include a memorial for Tim Olmstead, the man who actually negotiated with DR and then painstakingly digitized the documents.

      Shame on you, Neil McAllister, for gobbling up a press release and not bothering to do the most basic research.

      1. HelpfulJohn Bronze badge

        Re: Lazy journalism

        Well, that's 21st Century "journalism"; snatch something off TwitFace and rush it to Press, hoping that the Good Editors know less than you do and that any calumnies and errors will be small enough to be forgiven.

        Not that any "Register" reporter would stoop to that, of course.

  14. IvyKing

    Pascal MT+

    I remember hearing about Pascal MT+ back in the early 80's, then ran across an ad for it in a 1981 issue of Byte Magazine. Looked at the address and realized it was a house a block away from where my kids attended 3rd through 6th grades.

    Small world.

  15. JT163

    Well it's not really a leak, if the "leakers" intend the material to be released.


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