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Control Program Facility

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Control Program Facility (CPF)
DeveloperIBM
Written inPL/MI, PL/MP, Assembly Language[1]
Working stateDiscontinued
Source modelClosed Source
Initial release1978; 47 years ago (1978)
Instruction setsIBM System/38 minicomputer
Default
user interface		Command-line interface
LicenseProprietary
Succeeded byOS/400

Control Program Facility (CPF) was the operating system for the IBM System/38. CPF evolved into the OS/400 operating system, which was originally known as XPF (Extended CPF).[1] CPF represented an independendent line of development at IBM Rochester, and was unrelated to the earlier and more widely used SSP operating system.

While CPF is considered to be the operating system of the System/38, it sits on top of the System/38 Machine Interface layer, and consequently much of the functionality of a traditional operating system is implemented in the Horizontal and Vertical Microcode layers of the platform. Consequently, CPF is analagous to the userspace of other operating systems in terms of its functionality and responsibilities.[2]

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).[3] 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

CPF was an example of a commercially-available Capability-based operating system. System/38 was one of the few commercial computers with capability-based addressing.[4] Capability-based addressing was removed in the follow-on AS/400 and iSeries models.[5]

Distributed Data Management

In 1986, System/38 announced support for Distributed Data Management Architecture (DDM). Such a middleware in the context of a distributed system is the software layer that lies between the operating system and applications. Distributed Data Management Architecture defines an environment for sharing data. This enables System/38 programs to create, manage, and access record-oriented files on remote System/36, System/38, and IBM mainframe systems running CICS. It also allows programs on remote System/36 and System/38 computers to create, manage, and access files of a System/38.

Programming languages

Languages supported on the System/38 included RPG III, COBOL, BASIC, and PL/I.

References

  1. ^ a b Frank G. Soltis (1997). Inside the AS/400, Second Edition. Duke Press. ISBN 978-1882419661.
  2. ^ Soltis, Frank (September 1981). "Design of a Small Business Data Processing System". IEEE Computer. 14: 77–93. doi:10.1109/C-M.1981.220610.
  3. ^ Mark Smotherman. "IBM Future System (FS) - 1970s". Retrieved October 11, 2017.
  4. ^ Levy, Henry M. (1984). "The IBM System/38" (PDF). Capability-Based Computer Systems. Digital Press. ISBN 0-932376-22-3.
  5. ^ 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..
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