System/360 definition

<computer>

The generic name for the CPUs and architecture released by IBM on 1964-04-07. The 360 was marketed as a general purpose computer with 'all round' functionality - hence 360 (degrees).

Models ranged from the 360/20 to the 360/65 and later the 360/95, with typical memory configurations from 16K to 1024K.

Elements of the architecture, such as the basic instruction set are still in use on IBM mainframes today. Operating System/360 (OS/360) was developed for System/360. Other associated operating systems included DOS, OS/MFT and OS/MVT.

The 360 architecture was based on an 8-bit byte, 16 general purpose registers, 24-bit addressing, and a PSW (Program Status Word) including a location counter.

Gene Amdahl, then an IBM employee, is generally acknowledged as the 360's chief architect. He later went on to found Amdahl Corporaton, a manufacture of PCM mainframe equipment.

The 360's predecessors were the smaller IBM 1401 and the large IBM 7090 series. If was followed by the IBM 370.

See also: ABEND, ALC, BAL, Big Red Switch, HCF, mode bit, PL360, PL/S.

(01 Sep 2004)