Honeywell CP-6

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Honeywell logo.svg
DeveloperHoneywell, Inc.
Written inPL-6
OS familyUniversal Time-Sharing System
Working stateHistoric, discontinued 2005
Source modelClosed source
Initial releaseBeta 1979
Marketing targetFormer XDS Sigma CP-V customers
PlatformsHoneywell Level/66 and successors
Default user interfaceCommand-line interface

CP-6 is a discontinued computer operating system developed by Honeywell, Inc. in 1976. It was a backward-compatible work-alike of the Xerox CP-V fully rewritten for Honeywell Level/66 hardware. CP-6 was a command line oriented system. A terminal emulator allowed use of PCs as CP-6 terminals.


In 1975, Xerox decided to sell the computer business which it had purchased from Scientific Data Systems in 1969. In a deal put together by Harry Sweatt, Honeywell purchased Xerox Data Systems,[1] and took on the Xerox sales and field computer support staff to provide field service support to the existing customer base. Xerox made available all the spare equipment and supplies and the warehouses containing them. Revenues were shared 60/40 Xerox until CP-6 General Release, and 60/40 Honeywell for three years thereafter. Following that all revenue went to Honeywell.

In the early 1960s, Honeywell had built and sold a large number of H200 machines, together with software. In 1970 it had bought the computer business of General Electric.

LADC and the development of CP-6[edit]

The CP-6 system including operating system and program products was developed, beginning in 1976, by Honeywell to attract Xerox CP-V users (about 750 Sigma users)[2] to buy and use Honeywell equipment.[3][4] Honeywell employed an initial team of 60 programmers from the Xerox CP-V development team, and added another 30 programmers plus management and staff. Organized by Hank Hoagland and Shel Klee, the team was housed at an old Xerox marketing office at 5250 W. Century Blvd in Los Angeles, which became known as the Los Angeles Development Center (LADC). The new operating system was to be called CP-6.[5] LADC reported administratively to the Honeywell computer group in Phoenix, a facility, which Honeywell had acquired from General Electric.

The first beta site was installed at Carleton University in Ottawa Canada in June 1979,[4] and three other sites were installed before the end of 1979. Customers worked with LADC both directly and through the Exchange Users group throughout the specification and development period to review and approve the direction of development, the compromises and order of feature implementation.

Comshare, a major Xerox customer, but with their own operating system, needed more capacity to service their rapidly expanding timesharing business. So, with the help of LADC hardware engineers and using the Xerox specifications, Honeywell engineers in Phoenix built 30 Sigma 9 computers, 24 for Comshare and 6 for other customers. This project was initiated in 1978, and the machines were sold at the original retail price and delivered beginning in the third quarter of 1979 until 1981.

The CP-6 product[edit]

CP-6 was modeled on Xerox's CP-V. The code was completely rewritten in a new high-level language, PL-6, designed and built expressly for that purpose, rather than in assembly language as CP-V had been, because of increasing complexities of the new virtual addressing hardware (such as that in Honeywell’s L66 and DPS 8 line).[6] During the rewrite existing weaknesses were addressed and many new features added.[4][7]

Like CP-V, CP-6 had five access modes, which operated concurrently: batch processing, remote batch, timesharing, transaction processing, and real-time processing. It included multiprogramming and operated on multiple CPUs.[8]

Also like CP-V, the design was an integrated file management system. Files were equally and compatibly available to programs executing in any mode. The files could be sorted in indexed, keyed, relative, or consecutive order.

New in CP-6 was the use of communications and terminal interfaces through minicomputer (Honeywell Level 6)-based front-end processors, connected locally, remotely, or in combination.

CP-6 included an integrated software development system which supported and included a set of language processors: APL,[9] BASIC,[10] COBOL, FORTRAN, RPG, IDP, IDS/II, SORT/MERGE, PL-6, GMAP, and a text formatting program, TEXT. Commonly needed software packages (Pascal, SNOBOL, LISP, SPSS, BMDP, IMSL, SPICEII, and SLAM) were developed by Carleton University.

The operating system supported inter-system communication, job submission and file transfer between CP-6 systems and between CP-6 and CP-V and to and from IBM and other HASP protocol systems. The system used communications and terminal interfaces through a Honeywell Level 6 minicomputer-based front-end processor. Asynchronous, bisynchronous and TCP/IP communications protocols were supported.

The Honeywell hardware system for CP-6 consisted of a mainframe host processor (L66, DPS8, DPS8000, DPS90),[11] to which connected disks, tapes, printers, and card equipment were connected. A high-speed channel connected this host to a Level 6 mini computer, which provided processing and connection for terminals, communications lines, and high-speed channel to remote computers, including LADC and customers for on-line support, new version download and problem fix patches. A terminal emulator allowed use of PCs as CP-6 terminals.

Product additions in the mid eighties included adaptation for DPS8000 Bull mainframe computers.[12]

Product support[edit]

CP-6 included an on-line problem reporting and fix system, beginning in 1976. That system was named System Technical Action Request (STAR), the people who oversaw the STAR system were STARlords. Programmers had direct access to customers' computers, and could fix problems directly on-line. The system used Honeywell's proprietary network.[13]


  1. ^ AUUG, Inc. (December 2002). AUUGN. AUUG, Inc. pp. 23–.
  2. ^ IDG Enterprise (16 June 1980). Honeywell Adds Mainframe for Xerox Users, Extends CP-6. Computerworld. IDG Enterprise. pp. 4–. ISSN 0010-4841.
  3. ^ Crisman, P. A.; Bryan, G. Edward (March 1981). "Management of Software Development for CP 6 at LADC". Proceedings of the Fifth Annual Honeywell International Software Conference.
  4. ^ a b c Warren Schwarzmann; IEEE, South Bay Harbor Section Staff (1994). IEEE Aerospace Applications Conference Proceedings. IEEE.
  5. ^ P.A. Crisman and Bryan, G. Edward, "Management of Software Development for CP 6 at LADC", Proceedings of the Fifth Annual Honeywell International Software Conference, March 1981.
  6. ^ Honeywell, Inc. (June 1988). CP-6 Introduction to PL-6 (PDF). Retrieved Sep 3, 2014.
  7. ^ Bryan, G Edward (March 2012). Not All Programmers Are Created Equal —Redux. 2012 IEEE Aerospace Conference Proceedings.
  8. ^ Datamation. Technical Publishing Company. January 1982.
  9. ^ Frost, Bruce, "APL and I-D-S/II APL access to large databases". in Association for Computing Machinery (1 April 1983). APL 83, Conference proceedings, Washington, D.C., April 10-13, 1983. The Association. pages 103-107
  10. ^ Ronald Brinkman (1 January 1984). Programming in Structured BASIC. Macmillan. ISBN 978-0-02-314870-5.
  11. ^ IDG Enterprise (9 March 1981). Honeywell Forecasts Changes in CP-6 Base - Computerworld. IDG Enterprise. pp. 6–. ISSN 0010-4841.
  12. ^ Computerworld. IDG Enterprise. 22 October 1979. pp. 34–. ISSN 0010-4841.
  13. ^ Fielding, Roy T (1992). An Empirical Microanalysis of Software Failure Data from a 12-Year Software Maintenance Process. University of California Irvine. p. Master's Thesis.

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