IBM System/34
| Company type | Computer system |
|---|---|
| Industry | Computer hardware |
| Predecessor | IBM System/32 |
| Founded | 1977 |
| Defunct | February 1985 |
| Successor | IBM System/36, IBM System/38 |
| Products | Midrange computer system |
The IBM System/34 was a midrange computer introduced by IBM in 1977 and remained in production until February 1985. It followed the single-user System/32 by providing a multi-user, multitasking platform equipped with two processors—one evolved from the System/32 and the other from the System/3. The System/34 primarily executed software developed in RPG II, ensuring continuity within IBM’s midrange software environment.
Hardware
The 5340 System Unit combined processing power, disk storage, and a diskette drive inside a cabinet designed with access panels and swing-out trays for circuit boards and memory modules. It weighed roughly and operated on a 220V power supply. Interaction with the system was mainly through terminals from the IBM 5250 family.
Processors
Two processors were integrated into the S/34: the Control Storage Processor (CSP) and the Main Storage Processor (MSP). The MSP, modeled on the System/3 architecture, was responsible for executing program code, while the CSP utilized a distinct RISC-like instruction set inherited from the System/32 to oversee background system tasks. The CSP also supported optional Scientific Macroinstructions, which emulated floating-point operations employed by the System/34 Fortran compiler and could be optionally accessed in assembly language. The MSP operated at a fixed clock speed of 1 MHz, whereas the CSP ran at 4 MHz. Certain utilities, including $CNFIG used for system configuration, directly interfaced with the CSP.
Memory and storage
The base S/34 configuration included 48K of RAM paired with an 8.6 MB hard disk; systems could be expanded up to 256K RAM and 256 MB of disk capacity. Hard drives incorporated an "extra cylinder" feature to remap defective sectors dynamically. Disk storage was segmented into blocks of 2560 bytes.
The System/34 supported memory paging, also known as swapping, enabling entire programs or individual segments to be temporarily moved out of memory to accommodate multiple simultaneous operations.
A unique aspect of its design was off-line storage via "magazines"—containers holding multiple 8-inch floppy disks that could be loaded and removed in any order. The diskette magazine drive was capable of managing up to 23 diskettes without manual handling.
Operating System
The only operating system available for the S/34 was the System Support Program (SSP), which facilitated multiprogramming, dual-processor operation, support for up to 36 peripheral devices, job and printer queue management, security features, and indexed file handling. A full SSP installation required approximately 5 MB of disk space. The Operational Control Language (OCL) functioned as SSP’s command language.
Programming
At its initial release in 1977, the System/34 primarily supported RPG II and Basic Assembler languages. FORTRAN became fully supported after six months, while COBOL was available through special request (PRPQ). Subsequently, System/34 BASIC was introduced, broadening programming capabilities for business-oriented applications.
Successor systems
The IBM System/38 was intended as the successor to both the System/34 and earlier System/3x series. However, delays in development coupled with costly hardware limited its market penetration. IBM instead launched the more cost-effective and widely adopted System/36, which evolved from System/34 architecture. Although not compatible at the object-code level, the System/36 allowed recompilation of System/34 source code with minimal modifications. Some hardware components from the System/34 were incompatible with this newer platform.
Third-party solutions like BABY/34 from California Software Products, Inc., enabled RPG II applications developed for System/34 to be ported to IBM PC compatible machines running MS-DOS, thereby extending the usability and flexibility of existing System/34 software investments.