Control Program Facility

Control Program Facility (CPF) was the operating system for the IBM System/38. CPF is not related to SSP.

Control Program Facility (CPF)
Initial release1978 (1978)
PlatformsIBM System/38 minicomputer
Default user interfaceCommand-line interface


A database management system was integrated with the operating system.

The System/38's advanced operating system lives on with IBM's AS/400. Great efforts were made by IBM to enable programs originally written for the System/34 and /36 to be moved to the AS/400.

Description of the libraries

  • QGPL – general purpose library
  • QSYS – system library
  • QSPL – spooling library
  • QTEMP – temporary library
  • QSRV – system service library
  • QRECOVERY – system recovery library

Data storage

In most computers prior to the System/38, and most modern ones, data stored on disk was stored in separate logical files. When data was added to a file it was written in the sector dedicated to this, or if the sector was full, on a new sector somewhere else.

The System/38 adopted the single-level store architecture, where main storage and disk storage are organized as one, from the abandoned IBM Future Systems project (FS).[1] Every piece of data was stored separately and could be put anywhere on the system. There was no such thing as a physically contiguous file on disk, and the operating system managed the storage and recall of all data elements.

Capability-based addressing

System/38 was one of the few commercial computers with capability-based addressing. (The earlier Plessey 250 was one of the few other computers with capability architecture ever sold commercially.) Capability-based addressing was removed in the follow-on AS/400 and iSeries models.[2] Capability-based operating system refers to an operating system that uses capability-based security.


  1. Mark Smotherman. "IBM Future System (FS) - 1970s". Retrieved October 11, 2017.
  2. Soltis, Frank G. (July 2001). Fortress Rochester: The Inside Story of the IBM ISeries. 29th Street Press. p. 119. ISBN 978-1-58304-083-6..
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.