IBM System/34

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IBM System/34
IBM System/34 type 5340
Also known asS/34
ManufacturerInternational Business Machines Corporation (IBM)
Product familySystem/34
Release dateApril 1977; 46 years ago (1977-04)
DiscontinuedFebruary 1985
Operating systemSystem Support Program
Memory48K - 256K
PredecessorIBM System/32
SuccessorIBM System/36, IBM System/38
RelatedIBM 5520
WebsiteOfficial website IBM Archives

The IBM System/34 was an IBM midrange computer introduced in 1977.[2] It was withdrawn from marketing in February 1985.[2] It was a multi-user, multi-tasking successor to the single-user System/32. It included two processors, one based on the System/32 and the second based on the System/3. Like the System/32 and the System/3, the System/34 was primarily programmed in the RPG II language.[3]


The 5340 System Unit contained the processing unit, the disk storage and the diskette drive. It had several access doors on both sides. Inside, were swing-out assemblies where the circuit boards and memory cards were mounted. It weighed 700 lb (320 kg) and used 220V power.[4] The IBM 5250 series of terminals were the primary interface to the System/34.


S/34s had two processors, the Control Storage Processor (CSP), and the Main Storage Processor (MSP). The MSP was the workhorse, based on System/3 architecture; it performed the instructions in the computer programs. The CSP was the governor, a different processor with different RISC-like instruction set, based on System/32 architecture; it performed system functions in the background. The CSP also executed the optional Scientific Macroinstructions, which were a set of emulated floating point operations used by the System/34 Fortran compiler and optionally in assembly code.[5] The clock speed of the CPUs inside a System/34 was fixed at 1 MHz for the MSP and 4 MHz for the CSP. Special utility programs were able to make direct calls to the CSP to perform certain functions; these are usually system programs like $CNFIG which was used to configure the computer system.

Picture of a System/34 showing the diskette magazine drive

Memory and storage[edit]

The smallest S/34 had 48K of RAM and an 8.6 MB hard drive. The largest configured S/34 could support 256K of RAM and 256MB of disk space. S/34 hard drives contained a feature called "the extra cylinder," so that bad spots on the drive were detected and dynamically mapped out to good spots on the extra cylinder. Disk space on the System/34 was organized by blocks of 2560 bytes.

The System/34 supported memory paging, referring to as swapping.[6] The System/34 could either swap out entire programs, or individual segments of a program in order to free up memory for other programs to run.

One of the machine's most distinctive features was an off-line storage mechanism that utilized "magazines" - boxes of 8-inch floppies that the machine could load and eject in a nonsequential fashion.[7][8][9]


IBM System/34 with 5251 terminal (on top) and 5211 printer (right, with top opened)

Operating System[edit]

The System Support Program (SSP) was the only operating system of the S/34. It contained support for multiprogramming, multiple processors, 36 devices, job queues, printer queues, security, indexed file support. Fully installed, it was about 5 MB.[10] The Operational Control Language (OCL) was the control language of SSP.


The System/34's initial programming languages were limited to RPG II and Basic Assembler[11] when introduced in 1977.[12] FORTRAN was fully available six months after the 34's introduction,[7] and COBOL was available as a PRPQ.[13] BASIC was introduced later.

Successor systems[edit]

The IBM System/38 was intended to be the successor of the System/34 and the earlier System/3x systems. However, due to the delays in the development of the System/38 and the high cost of the hardware once complete, IBM developed the simpler and cheaper System/36 platform which was more widely adopted than the System/38.[14] The System/36 was an evolution of the System/34 design, but the two machines were not object-code compatible. Instead, the System/36 offered source code compatibility, allowing System/34 applications to be recompiled on a System/36 with little to no changes. Some System/34 hardware was incompatible with the System/36.

A third party product from California Software Products, Inc. named BABY/34 allowed System/34 applications to be ported to IBM PC compatible hardware running MS-DOS. [15] [16]


  1. ^ ibm :: system34 :: GA21-9242-1 System 34 Installation Manual-Physical Planning Sep77. 1977-03-13.
  2. ^ a b IBM Corporation (23 January 2003). "System/34". IBM Archives. Retrieved December 4, 2012.
  3. ^ "System 34 RPG II Reference Manual" (PDF).
  4. ^ "3533 Spring Creek Road". The New York Times. March 1, 2019. Insulated Shop space, with 220V power.
  5. ^ "IBM System/34 and IBM System/32 Scientific Macroinstructions Functions Reference Manual" (PDF). Bitsavers. IBM. July 1978. Retrieved 2021-12-22.
  6. ^ "System/34 Concepts and Design Guide" (PDF). IBM. January 1982. Retrieved 2021-08-01.
  7. ^ a b System/34 Introduction (PDF). March 1978.
  8. ^ "the diskette magazine drive can process up to 23 diskettes without manual intervention. -p.11
  9. ^ "three slots for holding individual diskettes and two slots for holding magazines of 10 individual diskettes." -p.20
  10. ^ "IBM System/34 System Support Program Logic Manual" (PDF).
  11. ^ "Fortran IV One Highlight Of IBM 34 Enhancements". Computerworld. September 26, 1977. p. 23.
  12. ^ Andrew Pollack (May 17, 1983). "I.B.M. introduces computer to replace System 34 model". The New York Times.
  13. ^ "potentially available ... special order"
  14. ^ Frank G. Soltis (1997). Inside the AS/400, Second Edition. Duke Press. ISBN 978-1882419661.
  15. ^ "BABY/34™ Software enables you to run IBM System/34 RPG II programs on your PCs, XTs and ATs". Computerworld. March 18, 1985. p. 50.
  16. ^ "Product Briefs". InfoWorld. July 21, 1986. p. 47.

Further reading[edit]

  • Massoglia, Charlie. Everything You Always Wanted to Know About the System/34 But Nobody Told You.
  • Massoglia, Charlie. Writing and Using System/34 Procedures Effectively.
  • Lee, Merikay. Everything You Always Wanted to Know About POP But Nobody Told You.
  • Massoglia, Charlie. System/3 and System/34 Disk Sort as a Programming Language.

External links[edit]

IBM midrange computers
Preceded by IBM System/34
1977 - 1985
Succeeded by
Preceded by