So a while back, I heard that MS-DOS was originally named QDOS (Quick and Dirty Operating System), and that it was later changed is MS-DOS (Microsoft Disk Operating System). This was probably a marketing strategy to fix a rather unappealing name. My question is when did this change take place, and why did it take place specifically then?

  • It might be worth mentioning that while MS-DOS was never called QDOS through its alive days, the operating system of the Sinclair QL was indeed officially called QDOS.
    – tofro
    Commented Nov 8, 2018 at 13:38
  • You may want to suggest that on the answer, instead.
    – Badasahog
    Commented Nov 8, 2018 at 14:18
  • That fact is actually not an answer to your question, that is why I put it in as a comment here.
    – tofro
    Commented Nov 8, 2018 at 15:27

1 Answer 1


MS-DOS was indeed originally known as QDOS. The change in name occurred as a result of a change in ownership — from Seattle Computer Products to Microsoft.

Tim Paterson, QDOS’ author, has documented this:

The first versions of the operating system, called QDOS 0.10, were shipped in August 1980. QDOS stood for Quick and Dirty Operating System because it was thrown together in such a hurry (two man-months), but it worked surprisingly well. [...]

In the last few days of 1980, a new version of the DOS was released, now known as 86-DOS version 0.3. [...]

In July 1981, Microsoft bought all rights to the DOS from Seattle Computer, and the name MS-DOS was adopted. Shortly afterward, IBM announced the Personal Computer, using as its operating system what was essentially Seattle Computer's 86-DOS 1.14. Microsoft has been continuously improving the DOS, providing version 1.24 to IBM (as IBM's version 1.1) with MS-DOS version 1.25 as the general release to all MS-DOS customers in March 1982.

IBM provided DOS with their PC as “PC DOS”.

An interesting artifact came to light earlier this year: a copy of Seattle DOS 3.1! As part of the sale of 86-DOS to Microsoft, SCP were granted a royalty-free license to DOS, for use with their computer hardware, and evidently continued to produce OEM versions of MS-DOS at least until version 3.1. (Microsoft bought the license back at the end of 1986.)

  • 8
    Since this paragraph isn't really an answer to the question, I'll make it as a comment. MSDOS and PCDOS remained co-marketed but virtually identical products until 1993, with version 6.1 of PCDOS. IBM dropped Microsoft's QBASIC and added their long-time house editor E. (The had to, because the MSDOS editor was QBASIC with a different skin. It was a net gain because E is an extremely nice text editor.) For their part, Microsoft dropped IBM's DOS SHell in their version 6.22. With PC DOS 7, IBM added the Rexx language to make up for no BASIC.
    – RichF
    Commented Nov 2, 2018 at 17:09
  • 1
    I still have a (paid, by me, back in the day!) copy of PCDOS 7-ish running on a VM for when I need that REXX goodness.
    – user12
    Commented Nov 2, 2018 at 18:12
  • Is this perchance why MS-DOS shipped with a "QBASIC"? Or was that a separate name that just happened to mimic the original QDOS name? Commented Nov 2, 2018 at 21:22
  • 5
    @madscientist159 QBasic was a BASIC interpreter and editor based on QuickBASIC, and the latter was part of the Quick... series of development environments which Microsoft developed to compete against Borland’s Turbo Range (QuickC and QuickPascal being the other two). I don’t think the naming had much to do with QDOS apart from the Q sharing the same meaning. Commented Nov 2, 2018 at 21:56
  • 2
    @Igor, just to clarify, Wirth did design/create Modula2 but I was talking specifically about the TopSpeed compilers developed by Neils Jensen. A mistake on my part was to state he developed TurboPas (I believe you are correct that it was Anders) when, in actuality, he headed the team developing Borland Modula-2 to replace TurboPas and serve as part of the new Borland C++ suite. When Borland bought in an external C++ compiler, he left to form Jensen&Partners, bought the rights from Borland and continued development. At least that's my memory of it, I could still be wrong :-)
    – user6464
    Commented Nov 18, 2018 at 1:20

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .