The Unix Time-Sharing System

  • Dennis M. Ritchie
  • Ken Thompson


UNIX is a general-purpose, multi-user, interactive operating system for the Digital Equipment Corporation PDP-11/40 and 11/45 computers. It offers a number of features seldom found even in larger operating systems, including: (1) a hierarchical file system incorporating demountable volumes; (2) compatible file, device, and inter-process I/O; (3) the ability to initiate asynchronous processes; (4) system command language selectable on a per-user basis; and (5) over 100 subsystems including a dozen languages. This paper discusses the nature and implementation of the file system and of the user command interface.


File System Command Line Open File Directory Entry Core Image 
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  1. 1.
    Digital Equipment Corporation. PDP-11/40 Processor Handbook, 1972, and PDP-11/45 Processor Handbook, 1971.Google Scholar
  2. 2.
    Deutsch, L.P., and Lampson, B.W. An online editor. Comm. ACM 10, 12 (Dec. 1967), 793–799, 803.CrossRefGoogle Scholar
  3. 3.
    Richards, M. BCPL: A tool for compiler writing and system programming. Proc. AFIPS 1969 SJCC, Vol. 34, AFIPS Press, Montvale, N.J., pp. 557–566.Google Scholar
  4. 4.
    McClure, R.M. TMG—A syntax directed compiler. Proc. ACM 20th Nat. Conf., ACM, 1965, New York, pp. 262–274.Google Scholar
  5. 5.
    Hall, A.D. The M6 macroprocessor. Computing Science Tech. Rep.#2, Bell Telephone Laboratories, 1969.Google Scholar
  6. 6.
    Ritchie, D.M. C reference manual. Unpublished memorandum, Bell Telephone Laboratories, 1973.Google Scholar
  7. 7.
    Aleph-null. Computer Recreations. Software Practice and Experience i, 2 (Apr.-June 1971), 201–204.Google Scholar
  8. 8.
    Deutsch, L.P., and Lampson, B.W. SDS 930 time-sharing system preliminary reference manual. Doc. 30.10.10, Project GENIE, U of California at Berkeley, Apr. 1965.Google Scholar
  9. 9.
    Feiertag, R.J., and Organiek, E.I. The Multics input-output system. Proc. Third Symp. on Oper. Syst. Princ, Oct. 18–20, 1971, ACM, New York, pp. 35–41.Google Scholar
  10. 10.
    Bobrow, D.G., Burchfiel, J.D., Murphy, D.L., and Tomlinson, R.S. TENEX, a paged time sharing system for the PDP-10. Comm. ACM 15, 3 (Mar. 1972), 135–143.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2001

Authors and Affiliations

  • Dennis M. Ritchie
  • Ken Thompson

There are no affiliations available

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