DeveloperSeattle Computer Products / Tim Paterson
Source modelClosed source
Initial release86-DOS 1.00
(30 April 1981)
Latest release86-DOS 1.14
(11 December 1981)
Supported platformsx86
Kernel typeMonolithic
User interfaceCommand-line interface

86-DOS, known internally and in official documents as QDOS, Q-DOS, Seattle DOS, and SCP-DOS,[1] is an operating system developed by Seattle Computer Products that was later licensed[2] and then bought[3] by Microsoft and used as the basis for IBM PC-DOS and MS-DOS.

History[edit | edit source]

Development of QDOS began in April 1980 out of the growing need for an 8086 operating system,[4] as CP/M-86 had been delayed since December 1979.[5][6] It was written on a Cromemco Z80 computer[7] running Cromemco's CDOS, in a text editing software called MicroPro WordMaster.[8][9] It was then translated using a Z80 to 8086 translator called TRANS-86 (which was later ported to 86-DOS and renamed to simply TRANS)[8][10] and tested on the Seattle Computer Products 16-bit Computer System.[11] QDOS was ready to ship in July, with Tim Paterson, the creator, spending about half of his time on its development.[4][12] Though the operating system wasn't completely finished, Paterson figured a quick release was more important than adding all the features.[13]

Though some parts of QDOS were written from scratch or by referencing the CP/M-80 manual,[14] others were created in Z80 assembly and then translated using the TRANS command.[15] Paterson claims that QDOS was created with CP/M translation compatibility being the goal[16] - however, these extreme similarities between the OSes caused controversy,[a] even going as far as a defamation case.[b] It has also been rumored that QDOS' development was aided by not only the CP/M manuals, but the source code as well[17] (or even Digital Research's original OEM translation tools).[18] However, these rumors are both unsourced and unlikely.[c]

Paterson later revealed he had mostly worked on hardware before QDOS, and that the idea came during his work on Seattle Computer products' 8086 board.[6] He decided on aspects of the OS because of his experience with North Star and Cromemco's variants of CP/M,[5] UCSD p-System, and Unix.[8][d] He also took inspiration for the filesystem from an unfinished 8-bit operating system known as Microsoft Interrupt Driven Asynchronous System (MIDAS[15] or M-DOS,[19] called MDOS before 1980[e]), written by Marc McDonald,[15][19] which he learned about during the 1979 National Computer Conference.[8]

List of known versions[edit | edit source]

Beta[edit | edit source]

86-DOS 1.xx[edit | edit source]

See also[edit | edit source]

Notes[edit | edit source]

  1. Perhaps the most compelling argument comes from the creator of CP/M, Gary Kildall - "Ask Bill why function code 6 (in DOS) ends with a dollar sign. ... No one in the world knows that but me." (quoted directly from Bill Gates: Of Mind and Money by James Wallace and Jim Erickson, published in the 8 May 1991 issue of Seattle Post-Intelligencer) Tim Paterson would later respond to this in Document 14-2 of the case Paterson v. Little, Brown, and Co., et al., reasoning that the name was in the CP/M manual he had.
  2. Paterson v. Little, Brown Co.
  3. The only way Seattle Computer Products could have had the CP/M source code or OEM translation tools was if they had a source code license from Digital Research - that too has also been rumored, though it is once again unsourced and not very likely.
  4. While uncited as an influence in the creation of QDOS, Paterson had also used CDC SCOPE, Cromemco RDOS, and the IMSAI 8080 Self-Contained System. (From Document 14-2 of Paterson v. Little, Brown, and Co., et al.)
  5. The exact date of the name change is unknown, but drafts of the user manual from 1979 and 1980 give an approximate date.

References[edit | edit source]

  1. United States District Court for the Western District of Washington (25 July 2007). Paterson v. Little, Brown, and Co., et al. - Order. Seattle Times. Case 2:05-cv-01719-TSZ Document 29.
  2. Brock, Rod; Allen, Paul (6 January 1981); Iowa District Court for Polk County. 86-DOS License Agreement with Microsoft; Plaintiff's Exhibit #1, Comes v. Microsoft.
  3. Brock, Rod; Allen, Paul (27 July 1981); Iowa District Court for Polk County. 86-DOS Agreement of Sale with Microsoft; Plaintiff's Exhibit #2, Comes v. Microsoft.
  4. 4.0 4.1 Hunter, David (March 1983). The Roots of DOS: Tim Paterson. Softalk for the IBM Personal Computer. p. 12-15.
  5. 5.0 5.1 Paterson, Tim (30 September 2007). Design of DOS. DosMan Drivel.
  6. 6.0 6.1 Bornstein, Howard (1986). MS-DOS (Versions 1.0-3.2) Technical Reference Encyclopedia. Microsoft Press. p. 8. ISBN 0-914845-69-1.
  7. Watt, Peggy (7 April 1986). MS-DOS creator Tim Paterson earns place in industry annals. Computerworld. p. 54.
  8. 8.0 8.1 8.2 8.3 Paterson, Tim (4 August 2018). VCF West XIII -- Tim Paterson -- Original DOS and the old days. Vintage Computer Federation.
  9. Glatzer, Hal (March 1984). Reflections on Past and Future With the Man From MS-DOS. Software News. p. 44 & 46.
  10. Microsoft Macro Assembler (MASM) Unofficial Changelist. BytePointer.
  11. Paterson, Tim (24 November 2007). The First DOS Machine. DosMan Drivel.
  12. Rojas, Raúl (April 2001). Encyclopedia of Computers and Computer History (A-L). Fitzroy Dearborn. ISBN 1-57958-235-4.
  13. Watt, Peggy (12 August 1991). PC-DOS, also 10, has its own storied past. Infoworld. p. 48.
  14. Cringely, Robert (June 1996). Triumph of the Nerds: The Rise of Accidental Empires (Season 1). PBS.
  15. 15.0 15.1 15.2 Manes, Stephen; Andrews, Paul (1993). Gates: How Microsoft's Mogul Reinvented an Industry—and Made Himself the Richest Man in America. Doubleday. p. 280-281. ISBN 0-385-42075-7.
  16. Välimäki, Mikko (2005). The Rise of Open Source Licensing. Turre. p. 88. ISBN 952-91-8779-3.
  17. Finley, Klint (7 August 2012). Was Microsoft's Empire Built on Stolen Code? We May Never Know. WIRED.
  18. Paul, Matthias (2000). 25 Years of DR-DOS History. FreeDOS.
  19. 19.0 19.1 Duncan, Ray (1988). The MS-DOS Encyclopedia. Microsoft Press. ISBN 1-55615-049-0.