The Free On-line Dictionary of Computing (30 December 2018):
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
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 PCMmainframe
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.