Xenix

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Xenix
SCO UNIX, OS/2

Xenix is a discontinued version of the Unix operating system for various microcomputer platforms, licensed by Microsoft from AT&T Corporation in the late 1970s. The Santa Cruz Operation (SCO) later acquired exclusive rights to the software, and eventually replaced it with SCO UNIX (now known as SCO OpenServer).

In the mid-to-late 1980s, Xenix was the most common Unix variant, measured according to the number of machines on which it was installed.[1][2] Microsoft chairman Bill Gates said at Unix Expo in 1996 that, for a long time, Microsoft had the highest-volume AT&T Unix license.[3]

History

16-bit microcomputer market.[6] Because Microsoft was not able to license the "Unix" name itself,[7]
the company gave it an original name.

Microsoft called Xenix "a universal operating environment".[8] It did not sell Xenix directly to end users, but licensed the software to OEMs such as IBM,[9] Intel,[10] Management Systems Development,[11] Tandy, Altos Computer, SCO, and Siemens (SINIX) which then ported it to their own proprietary computer architectures.

IBM/Microsoft Xenix 1.00 on 5¼-inch floppy disk

In 1981, Microsoft said the first version of Xenix was "very close to the original Unix version 7 source" on the

Z8001 product.[12]
: 14  The first 8086 port was for the Altos Computer Systems' non-PC-compatible 8600-series computers (first customer ship date Q1 1982).[note 1][12]: 3 [13][14][15]

Intel sold complete computers with Xenix under their Intel

TRS-80 Model 16 68000-based computer in early 1983,[17] and was the largest Unix vendor in 1984.[18] Seattle Computer Products also made (PC-incompatible) 8086 computers bundled with Xenix, like their Gazelle II, which used the S-100 bus and was available in late 1983 or early 1984.[12]: 17 [19] There was also a port for IBM System 9000.[20]

SCO had initially worked on its own PDP-11 port of V7, called Dynix,

Logica plc in the United Kingdom, as part of making further improvements to Xenix and porting Xenix to other platforms.[21] In doing so, Microsoft gave HCR and Logica the rights to do Xenix ports and to license Xenix binary distributions in those territories.[22]

In 1984, a port to the 68000-based

shrink-wrapped binary product sold by SCO.[23] The Multiplan spreadsheet was released for it.[24]

In its 1983 OEM directory, Microsoft said the difficulty in porting to the various 8086 and Z8000-based machines had been the lack of a standardized memory management unit and protection facilities. Hardware manufacturers compensated by designing their own hardware, but the ensuing complexity made it "extremely difficult if not impossible for the very small manufacturer to develop a computer capable of supporting a system such as Xenix from scratch," and "the Xenix kernel must be custom-tailored to each new hardware environment."[12]: Introduction 

A generally available port to the unmapped

4.2BSD; it also supported the Micnet local area networking.[28]

The later 286 version of Xenix used the integrated MMU present on this chip, by running in

dumb terminal
users under this version.

While Xenix 2.0 was still based on Version 7 Unix,

System V R2 codebase in Xenix 5.0 (a.k.a. Xenix System V).[33]

"Microsoft hopes that Xenix will become the preferred choice for software production and exchange", the company stated in 1981.

upwardly compatible with Xenix, which Byte in 1983 described as "the multi-user MS-DOS of the future".[36][37] Microsoft's Chris Larson described MS-DOS 2.0's Xenix compatibility as "the second most important feature".[38] His company advertised DOS and Xenix together, describing MS-DOS 2.0 (its "single-user OS") as sharing features and system calls with Xenix ("the multi-user, multi-tasking, Unix-derived operating system"), and promising easy porting between them.[39]

After the breakup of the Bell System in 1982, AT&T started selling System V.[40] Microsoft, believing that it could not compete with Unix's developer, decided to abandon Xenix. The decision was not immediately transparent, which led to the term vaporware.[41] It agreed with IBM to develop OS/2,[4] and the Xenix team (together with the best MS-DOS developers)[citation needed] was assigned to that project. In 1987, Microsoft transferred ownership of Xenix to SCO in an agreement that left Microsoft owning slightly less than 20% of SCO (this amount prevented both companies from having to disclose the exact amount in the event of an SCO IPO). And SCO would acquire both of the other companies that had Xenix rights,[22] Logica's software products group in 1986 and HCR in 1990.[42][43] When Microsoft eventually lost interest[clarification needed] in OS/2 as well, the company based its further high-end strategy on Windows NT.

In 1987,

TCP/IP
. SCO's Xenix System V/386 was the first 32-bit operating system available on the market for the x86 CPU architecture.

Microsoft continued to use Xenix internally, submitting a patch to support functionality in Unix to AT&T in 1987, which trickled down to the code base of both Xenix and SCO Unix. Microsoft is said to have used Xenix on

Exchange Server product.[45]

SCO released its

SCO Unix as a higher-end product, based on System V R3 and offering a number of technical advances over Xenix; Xenix remained in the product line. In the meantime, AT&T and Sun Microsystems completed the merge of Xenix, BSD, SunOS and System V R3 into System V R4. The last version of SCO Xenix/386 itself was System V R2.3.4, released in 1991.[46]

Features

Aside from its AT&T Unix base, Xenix incorporated elements from

electronic mail, although UUCP was still used for networking via modems.[9]

OEMs often added further modifications to the Xenix system.[9][10]

Trusted Xenix

Trusted Xenix was a variant initially developed by IBM, under the name Secure XENIX; later versions, under the Trusted Xenix name, were developed by Trusted Information Systems.[47] It incorporated the Bell–LaPadula model of multilevel security, and had a multilevel secure interface for the STU-III secure communications device (that is, an STU-III connection would be made available only to those applications running at the same privilege level as the key loaded in the STU-III). It was evaluated by formal methods and achieved a B2 security rating under the DoD's Trusted Computer System Evaluation Criteria—the second highest rating ever achieved by an evaluated operating system.[48] Version 2.0 was released in January 1991, version 3.0 in April 1992, and version 4.0 in September 1993.[49] It was still in use as late as 1995.

See also

  • AT&T 6300 Plus
  • Concurrent DOS
  • PC/IX
  • Venix

Notes

  1. ^ The Altos 8086 machines had a custom MMU, which used 4K pages.
  2. iRMX
    operating system as an alternative for these.
  3. Dynix from Sequent Computer Systems

References

  1. ^ Kelleher, Joanne (1986-02-03). "Corporate Unix: A system struggles to earn its stripes". Computerworld. p. 44.
  2. ISBN 0-201-06196-1
    .
  3. ^ "UNIX Expo — Remarks by Bill Gates". Microsoft. 1996-10-09. Archived from the original on 2001-08-18. Retrieved 2013-09-09.
  4. ^
    Usenet: [email protected]
    . Retrieved 2013-11-06.
  5. ISBN 978-0-201-87721-2
    . p. 9 "Microsoft licensed Seventh Edition Unix from AT&T in 1978 to produce the Xenix operating system initially for the PDP-11."
  6. ^ "The History of Microsoft - 1980".
  7. ^ "Xenix variant information". 2010-02-26. Archived from the original on 2013-12-19. In the late 1970s Microsoft licensed Unix source code from AT&T, which at the time was not licensing the name Unix.
  8. ^ a b c Greenberg, Robert B. (June 1981). "The Unix Operating System and the Xenix Standard Operating Environment". Byte. pp. 248–264.
  9. ^
    doi:10.1147/sj.241.0026
    .
  10. ^
    Intel Corporation
    . November 1984. Xenix 286 is Intel's value-added version of the Xenix operating system released by Microsoft Corporation.
  11. BYTE
    (advertisement). October 1981. p. 380. Retrieved 2016-03-16.
  12. ^ a b c d e f g Microsoft Xenix Operating System OEM Directory, May 1, 1983, Part No. OEM0091B
  13. ISSN 0010-4841
    .
  14. ISSN 0199-6649
    .
  15. ISSN 0010-4841
    .
  16. ^ "Introduction to the System 86/360 and System 86/330A Microcomputer Sysetms" (PDF). bitsavers. Intel. 1983. Retrieved 2022-11-30.
  17. ^ Chin, Kathy (1983-02-07). "Radio Shack goes to Microsoft's Xenix for Model 16 micros". InfoWorld. p. 3. Retrieved 2015-01-31.
  18. ^ Bartimo, Jim (1985-03-11). "Tandy Revamps Product Line". InfoWorld. pp. 28–29. Retrieved 2015-01-21.
  19. ^ Gazelle II 16-bit Micro-Computer (PDF), Seattle Computer Products, Inc., 1983, archived (PDF) from the original on 2022-08-11
  20. ^ BYTE Guide to the IBM PC, fall 1984, p.61
  21. ^ a b Pate 1996, p. 9 "The Santa Cruz Operation (SCO) was formed in 1979 by Larry and Doug Michels as a technical management consulting business. [...] SCO then changed its focus from consulting to the custom porting of Unix system software and applications. The first version of Unix which SCO developed and sold was called Dynix, a name subsequently used by Sequent. The operating system was based on Seventh Edition Unix and ran on the PDP-11. [...] In 1982, a joint development and technology exchange agreement was reached between SCO and Microsoft bringing together engineers from SCO and Microsoft to further enhance the Xenix operating system which was increasing in popularity. Microsoft and SCO worked together with Logica in the UK and HCR in Canada, producing enhancements to Xenix and porting Xenix to other platforms."
  22. ^ a b Isenberg, Sara (2016-04-21). "Watch: A look-back conversation with Doug Michels, co-founder of SCO". Santa Cruz Tech Beat. See around 10:45 mark of interview video.
  23. ^ Pate 1996, p. 10 "In 1984 a port of Xenix was made to the Apple Lisa by SCO and Microsoft, and was subsequently sold successfully by SCO as their first binary product, showing the success of the shrink-wrapped market. A port was also made to the Tandy model 16B."
  24. ^ Photograph of Lisa Xenix Multiplan diskette (JPEG) (Digital photography). Postimg.com. Retrieved 2019-09-24.
  25. ^ Hare, John Bruno; Thomas, Thomas Dean (1984). "Porting Xenix to the Unmapped 8086". Proceedings of the USENIX Winter Conference. Washington, D.C.: USENIX Association.
  26. ^ "SCO Company History". Operating System Documentation Project. Retrieved 2008-05-14.
  27. ^ Barger, Jorn. "Timeline of GNU/Linux and Unix". Retrieved 2008-05-14.
  28. ^ Pate 1996, p. 10 "In 1983 the PC [XT] emerged. SCO started porting to the 8088 but concentrated on the 8086, producing a release of SCO Xenix in 1984 which ran in 640 Kbytes with a 10 Mbyte hard disk. The release could support three or more users simultaneously, had multiscreen (virtual console) facilities, Micnet local area networking and enhancements added from 4.2BSD."
  29. ^ Microsoft Xenix 3.0 ready for 286 Archived January 7, 2014, at the Wayback Machine
  30. ISBN 978-1-56592-037-8
    .
  31. ISBN 978-0-596-55049-3
    .
  32. ISBN 978-0-8247-2272-2
    .
  33. ISBN 978-0-13-686494-3
    . The Xenix 2.3 version generally resembles V7's [ABI]; the Xenix 3.0 version resembles SIII's, and the Xenix 5.0 version resembles SV2's.
  34. ^
    BYTE
    . p. 330. Retrieved 2016-03-23.
  35. Swaine, Michael (1982-08-23). "MS-DOS: examining IBM PC's disk-operating system". InfoWorld
    . p. 24. Retrieved 2015-01-29.
  36. ^ Morgan, Chris (January 1982). "Of IBM, Operating Systems, and Rosetta Stones". Byte. p. 6. Retrieved 2013-10-19.
  37. BYTE
    . p. 132. Retrieved 2015-01-30.
  38. BYTE
    . p. 285. Retrieved 2016-03-19.
  39. ^ "Before you bet your business software on an OS, look who's betting on MS-DOS and Xenix". InfoWorld (advertisement). 1983-06-27. p. 44. Retrieved 2015-01-31.
  40. ^ Shea, Tom (1984-02-20). "New developments may decide battle over Unix". InfoWorld. pp. 43–45. Retrieved 2016-02-25.
  41. ^
    ISSN 0362-4331
    . Retrieved 2010-04-14.
  42. ^ "Santa Cruz Operation Ltd. to Offer Source for Xenix". InfoWorld. 1986-12-08. p. 33.
  43. ^ "California firm acquires Unix-systems leader". The Ottawa Citizen. Canadian Press. 1990-05-10. p. H8 – via Newspapers.com.
  44. Usenet: [email protected]
    . Retrieved 2006-10-25.
  45. ^ "Microsoft's Migration to Microsoft Exchange Server - The Evolution of Messaging within Microsoft Corporation". Microsoft. Archived from the original on 2005-04-27.
  46. ^ Pate 1996, p. 10
  47. S2CID 15376270
  48. ISBN 978-1-59829-212-1
    .
  49. ^ Lévénez, Éric (2011-05-01). "UNIX History". levenez.com. Retrieved 2011-05-18.

Further reading

External links

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