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The Beige Years

The Fake Error Microsoft Hid to Kill DR-DOS

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DR DOS beat MS-DOS in the reviews, so Microsoft hid a fake error in Windows 3.1 to scare its users away.

How an encrypted "Non-Fatal error", a beta blacklist and a tax on every PC buried the better DOS, and what it cost Microsoft.

Subject
DR-DOS against MS-DOS, 1988
Chapters
8
Sources
8
Credits
94
Corrections
0

Sources

8
  • Article7
  • Book1

The sources the story leans on most, primary sources first. Read dates are when the page was consulted; the live page may have changed since.

  1. [1]
    Article Andrew Schulman, Ralf Brown, David Maxey, Raymond J. Michels, Jim Kyle

    Undocumented DOS: A Programmer's Guide to Reserved MS-DOS Functions and Data Structures

    archive.org/details/undocdos2ed ↗
  2. [2]
  3. [3]
  4. [4]
    Article Stewart Cheifet Productions, *The Computer Chronicles*

    Windows 3.0

    archive.org/details/windows30 ↗
  5. [5]
  6. [6]
  7. [7]
  8. [8]

Image & music credits

94
  • License unknown87
  • CC BY-SA 4.03
  • CC BY-SA 2.01
  • CC BY 4.01
  • CC BY 2.01
  • CC BY 3.01

93 photos, 1 music track, from the hosts linked below. Each file name links to the file's page, which carries the full license terms.

#UseFileAuthorLicense
1 Photo DR-DOS 6.0 Digital Research.jpg Jcarloso CC BY-SA 4.0
2 Photo 24 High Street Hungerford Geograph-4011246-by-Mike-Smith.jpg Mike Smith CC BY-SA 2.0
3 Photo Microsoft Serial Mouse 2.0A-8519.jpg Raimond Spekking CC BY-SA 4.0
4 Photo https://archive.org/download/dr-dos-5.0-user-guide-1990-05/DR DOS 5.0 BoxFront.png archive.org License unknown
5 Photo A80386DX-25 SX218.jpg Mister rf CC BY-SA 4.0
6 Photo Federal Trade Commission logo Washington DC 2025-04-05 14-07-24.jpg G. Edward Johnson CC BY 4.0
7 Photo us v ms 1994 complaint tax hl.png U.S. Department of Justice, complaint of 15 July 1994, as published in the Federal Register, 59 FR 42845 (19 Aug 1994); set in its own text, the quoted words highlighted License unknown
8 Photo ms amstrad license 1990 royalty hl.png Microsoft-Amstrad License Agreement, 1 July 1990, Exhibit C1 (Comes v. Microsoft, Plaintiff's Exhibit 5130; techrights.org scan), the clause highlighted License unknown
9 Photo caldera facts 1999 p137 hl.png Caldera v. Microsoft, Consolidated Statement of Facts, April 1999, para. 137; set in its own text, the quoted words highlighted License unknown
10 Photo caldera facts 1999 p225 hl.png Caldera v. Microsoft, Consolidated Statement of Facts, April 1999, para. 225 (Exhibit 194); set in its own text, the quoted words highlighted License unknown
11 Photo caldera facts 1999 p233 hl.png Caldera v. Microsoft, Consolidated Statement of Facts, April 1999, para. 233; set in its own text, the quoted words highlighted License unknown
12 Photo caldera complaint 1996 hl.png Caldera, Inc. v. Microsoft Corp., complaint filed 23 July 1996, D. Utah, No. 2:96-CV-645 B; set in its own text, the quoted words highlighted License unknown
13 Photo drdos60 box front.jpg DR DOS 6.0 retail box, Digital Research, 5.25" disks (eBay listing photo); https://www.ebay.com/p/4029613423 License unknown
14 Photo win31 beta1 diskettes apr1991.jpg Windows 3.1 Beta 1 Build 34f (Internet Archive); https://archive.org/details/windows-3.1-beta-1-build-34f License unknown
15 Photo caldera logo 1994.png Caldera 1994 logo (Wikimedia Commons SVG, rendered PNG); https://commons.wikimedia.org/wiki/File:Caldera_1994_logo.svg License unknown
16 Photo microsoft campus 1980s.jpg Redmond History: 1981-1990 (Redmond Historical Society); https://www.redmondhistoricalsociety.org/post/redmond-history-1981-1990 License unknown
17 Photo drdos33 users guide.jpg DR DOS User's Guide, Release 3.3 (Retro Unit); https://retrounit.com.au/ License unknown
18 Photo cpm86 package ibmpc.jpg CP/M-86 disk package (The Silicon Underground); https://dfarq.homeip.net/dr-dos-revenge-of-cp-m/ License unknown
19 Photo ibm pc dos 10 binder.jpg IBM DOS 1.0 and Microsoft Windows 1.0 Software (RR Auction lot photo); https://www.rrauction.com/ License unknown
20 Photo undocumented dos 1990 cover.jpg Undocumented DOS (Internet Archive scan, front cover); https://archive.org/details/undocumented-dos License unknown
21 Photo msdos33 box.jpg MS-DOS 3.3 (Old Computer Museum); http://oldcomputermuseum.com/os/msdos_3.3.html License unknown
22 Photo pcdos40 box.jpg PC DOS 4.0 (Old Computer Museum); https://oldcomputermuseum.com/os/pcdos_4.0.html License unknown
23 Photo drihq 1980s.jpg "Figure 45. Digital Research headquarters" from Fire in the Valley (courtesy Tom; https://apprize.best/science/fire/5.html License unknown
24 Photo drdos50 user guide.jpg Digital Research DR-DOS 5.0 User Guide (eBay); https://www.ebay.com/itm/326266870985 License unknown
25 Photo drdos50 box tossyourdos.jpg DR DOS 5.0 retail box (The Silicon Underground); https://dfarq.homeip.net/dr-dos-revenge-of-cp-m/ License unknown
26 Photo drdos50 box sealed.jpg DR DOS 5.0 sealed box (Virtually Fun); https://virtuallyfun.com/2016/02/14/build-an-at-for-1000/ License unknown
27 Photo drdos60 user guide.jpg DR DOS 6.0 User Guide (eBay listing photo); https://www.ebay.com/p/4029613423 License unknown
28 Photo wordstar template kaypro.jpg KayPro WordStar keyboard template (Marcin Wichary, Flickr); https://www.flickr.com/ License unknown
29 Photo vobis highscreen 386.jpg Highscreen 386 (andreas-mausch.de); https://andreas-mausch.de/blog/2020-09-07-highscreen-386/ License unknown
30 Photo microsoft campus aerial 1989.jpg 1989 Redmond campus aerial (connect.de, (c) Microsoft); https://www.connect.de/ratgeber/microsoft-50-jahre-firmengeschichte-dos-windows-phone-azure-copilot-3208999.html License unknown
31 Photo novell teeth logo.png Novell "teeth" logo, stacked (Wikimedia Commons SVG, rendered PNG); https://commons.wikimedia.org/wiki/File:Novell_teeth_logo_stacked.svg License unknown
32 Photo microsoft file 1998 cover.jpg The Microsoft file: the secret case against Bill Gates (Internet Archive scan, c; https://archive.org/details/microsoftfilesec0000rohm License unknown
33 Photo netware311 box.jpg NetWare 3.11 box (zx.net.nz Netware 3.11 Notes); https://www.zx.net.nz/netware/server/311.shtml License unknown
34 Photo windows30 box.jpg Windows 3.x box (Retromobe); https://www.retromobe.com/2020/05/ License unknown
35 Photo caldera v ms 72fsupp2d 1303 scan hl.png Caldera, Inc. v. Microsoft Corp., 72 F. Supp. 2d 1295, 1303 (D. Utah, 3 Nov 1999); page scan via the Caselaw Access Project (static.case.law), the quoted words highlighted License unknown
36 Photo caldera v ms 72fsupp2d 1319 scan hl.png Caldera, Inc. v. Microsoft Corp., 72 F. Supp. 2d 1295, 1319 (D. Utah, 3 Nov 1999); page scan via the Caselaw Access Project (static.case.law), the quoted words highlighted License unknown
37 Photo undocumented windows 1992 cover.jpg Undocumented Windows (Internet Archive scan, cover); https://archive.org/details/undocumentedwind00schu License unknown
38 Photo novelldos7 box.jpg Novell DOS 7 (Old Computer Museum); https://www.oldcomputermuseum.com/os/novelldos_7.html License unknown
39 Photo novell v canopy 2004 retaliate scan hl.png Novell, Inc. v. The Canopy Group, Inc., 92 P.3d 768, 770 (Utah Ct. App. 2004); page scan via the Caselaw Access Project (static.case.law), the quoted words highlighted License unknown
40 Photo caldera network desktop cd.jpg Cleaning out and found this (r/linuxmasterrace); https://www.reddit.com/r/linuxmasterrace/ License unknown
41 Photo caldera network desktop cd label.png Caldera Network Desktop 1.0 CD label (Internet Archive); https://archive.org/details/caldera-network-desktop-1.0 License unknown
42 Photo novell v canopy 2004 purpose scan hl.png Novell, Inc. v. The Canopy Group, Inc., 92 P.3d 768, 770 (Utah Ct. App. 2004); page scan via the Caselaw Access Project (static.case.law), the quoted words highlighted License unknown
43 Photo https://winworldpc.com/res/img/screenshots/Microsoft Mail 2.1 - Edit.png winworldpc.com License unknown
44 Photo ms 2009 brief p16 280m hl.png Microsoft's Memorandum in Opposition, Novell v. Microsoft (Nov 2009), p. 16 (Groklaw copy via the Wayback Machine), the sentence highlighted License unknown
45 Photo infoworld 19900430 p3 dos revision.jpg InfoWorld via Google Books (LjsEAAAAMBAJ, PP3) License unknown
46 Photo infoworld 19901022 retail dos5 bigbucks.png InfoWorld via Google Books (GTwEAAAAMBAJ, PT118) License unknown
47 Photo https://archive.org/download/dr-dos-5.0-user-guide-1990-05/DR DOS 5.0 User Guide-1990-05/page/n416.jpg archive.org License unknown
48 Photo https://www.seasip.info/Gem/History/viewmax1.png www.seasip.info License unknown
49 Photo infoworld 19900514 drdos update direct.jpg InfoWorld via Google Books (MDsEAAAAMBAJ, PT12) License unknown
50 Photo infoworld 19910617 p6 dos5 discounts.jpg InfoWorld via Google Books (TFAEAAAAMBAJ, PA6) License unknown
51 Photo infoworld 19901022 cover dos5.jpg InfoWorld via Google Books (GTwEAAAAMBAJ, front cover) License unknown
52 Photo infoworld 19910415 toss your dos ad.jpg InfoWorld via Google Books (4FAEAAAAMBAJ, PT89) License unknown
53 Photo https://archive.org/details/bub gb ZFAEAAAAMBAJ/page/n91 archive.org License unknown
54 Photo https://archive.org/details/eu BYTE-1990-08 OCR/page/n142 archive.org License unknown
55 Photo https://archive.org/details/bub gb ZFAEAAAAMBAJ/page/n90 archive.org License unknown
56 Photo https://upload.wikimedia.org/wikipedia/commons/f/f3/Wordperfect-5.1-dos.png upload.wikimedia.org License unknown
57 Photo https://archive.org/details/bub gb iVAEAAAAMBAJ/page/n62 archive.org License unknown
58 Photo https://archive.org/details/1991-11-compute-magazine/page/n69 archive.org License unknown
59 Photo infoworld 19910722 p1 novell dri.jpg InfoWorld via Google Books (f1AEAAAAMBAJ, PA1) License unknown
60 Photo infoworld 19911104 p85 drdos6 review.png InfoWorld via Google Books (Xz0EAAAAMBAJ, PA85) License unknown
61 Photo https://archive.org/details/undocdos2ed/page/n34 archive.org License unknown
62 Photo https://archive.org/download/undocdos2ed/page/cover w1200.jpg Internet Archive, undocdos2ed (cover) License unknown
63 Photo http://toastytech.com/guis/win95boot.png toastytech.com License unknown
64 Photo novell teeth logo.png Wikimedia Commons, Novell_teeth_logo_stacked.svg (rendered) License unknown
65 Photo silverberg 1995ish seattlepi 1200.jpg https://www.seattlepi.com/business/tech/article/Microsoft-buys-LinkedIn-for-26-2-billion-8098479.php (Undated; caption: 'An undated handout photo of Microsoft's W) License unknown
66 Photo gates 1987 excel history.jpg https://www.history.com/videos/history-uncut-bill-gates-unveils-microsoft-excel-1987 (1987 (title of the History.com clip 'Bill Gates unveils Micr) License unknown
67 Photo kildall 1988 oneal.jpg https://computerhistory.org/blog/gary-kildall-40th-anniversary-of-the-birth-of-the-pc/ (1988: CHM caption 'Gary Kildall in 1988. Photo: Copyright To) License unknown
68 Photo gates 1985 verge halebian.jpg https://www.theverge.com/2015/11/19/9759874/microsoft-windows-35-years-old (1985: the article text under it reads 'Back in 1985, Windows) License unknown
69 Photo ballmer 1985 commercial skoften.jpg https://www.skoften.net/skft/4043307/microsoft-ceo-steve-ballmer-helemaal-los-in-windows-1-0-reclame-in-1986 (1985-86 (the Windows 1.0 TV commercial, page title says 1986) License unknown
70 Photo myhrvold 1996 charlierose.jpg https://charlierose.com/videos/15595 (12 Dec 1996 (page: 'Group Vice President at Microsoft Nathan) License unknown
71 Photo nixon 1973 ap orlando podium.jpg https://www.canoncitydailyrecord.com/2025/11/17/today-in-history-richard-nixon-says-im-not-a-crook/ (17 Nov 1973: AP caption 'In this Nov. 17, 1973 file photo, P) License unknown
72 Photo lieven 2000 bookcover.jpg https://www.digisaurier.de/fast-vergessen-9-was-wurde-eigentlich-aus-vobis/ (c.2000 (the Hanser book; the same site shows a copy signed b) License unknown
73 Photo noorda 1994 bbc business.jpg https://vhistory.wordpress.com/2015/05/06/the-business-bill-gates-tape-1826/ (BBC Two 'The Business: The Rise and Rise of Bill Gates', air) License unknown
74 Photo benson 2003 deseret.jpg https://www.deseret.com/utah/2020/11/30/21729800/news-u-s-district-judge-dee-benson-dies-at-age-72/ (22 Aug 2003: caption 'Judge Dee Benson speaks at the investi) License unknown
75 Photo schulman undoc dos blogspot b.jpg https://indrekis2.blogspot.com/2018/07/undocumented-dos-1st-edition.html (1990 (first edition); NOT a photo of the person) License unknown
76 Photo noorda portrait kanwal.jpg https://kanwalrekhi.com/ray-noorda/ (UNDATED: official corporate portrait; he looks late-60s (bor) License unknown
77 Photo benson portrait deseret 800x1120.jpg https://www.deseret.com/utah/2020/11/30/21729800/news-u-s-district-judge-dee-benson-dies-at-age-72/ (UNDATED court portrait (he looks mid-50s to 60s, so 2000s); ) License unknown
78 Photo https://archive.org/details/bub gb 7zsEAAAAMBAJ/page/n115 archive.org License unknown
79 Photo https://archive.org/details/bub gb ZFAEAAAAMBAJ/page/n91 archive.org License unknown
80 Photo cdos386 r3 ver window.png vintagecomputing.info (2019), PCem capture of Concurrent DOS 386 Release 3.0, emulator frame cropped License unknown
81 Photo https://archive.org/details/PC-Mag-1991-01-15/page/n131 archive.org License unknown
82 Photo gates 1995 reuters newsweek.jpg https://www.newsweek.com/ (Reuters, 1995: 'Microsoft Chairman Bill Gates...') License unknown
83 Photo https://www.gsa.gov/system/files/styles/fancy box carousel full/private/Moss event 04222022 2.jpg?itok=MMxDUkzW www.gsa.gov License unknown
84 Photo ballmer triumph 1996 vhistory.jpg https://vhistory.wordpress.com/2018/07/09/ (1995-96 interview, broadcast 1996 (Ballmer is 'bullish about) License unknown
85 Photo gates 1984 vintag 3.jpg vintag.es (1984 photograph of Bill Gates) License unknown
86 Photo https://winworldpc.com/res/img/screenshots/50-a474311b75757746463a0e0fb7188ebd-dosshell1.PNG WinWorld, MS-DOS 5.0 License unknown
87 Photo vobis highscreen kompakt 386sx.jpg majortom.de, Highscreen 386 SX (c.1991), http://www.majortom.de/hw/386sx/ License unknown
88 Photo vobis highscreen kompakt monitor.jpg majortom.de, Highscreen 386 SX (c.1991), http://www.majortom.de/hw/386sx/ License unknown
89 Photo gates 1984 tandy commons.jpg Wikimedia Commons, Bill Gates with Tandy 2000 running Windows (1984) License unknown
90 Photo https://winworldpc.com/res/img/screenshots/eaf36386209604f84929572ff2b13effe1af00b2624962e63458ba9fd58baf73.png WinWorld, Windows 3.1 License unknown
91 Photo drdos60 box novell.jpg eBay listing photo (Novell-branded DR DOS 6.0) License unknown
92 Photo gateway2000 cow boxes factory.jpg TechSpot, Gateway 2000 factory (early-mid 1990s) License unknown
93 Photo Downtown Seattle from Jose Rizal Park, 1998 (54136196970).jpg Laurel Mercury via Seattle Municipal Archives from Seattle, WA CC BY 2.0
94 Music Industrial Cinematic (ISRC USUAN1600047).mp3 "Industrial Cinematic" by Kevin MacLeod (incompetech.com) CC BY 3.0

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