IBM Personal System

IBM Personal System/2 series of computers
Developer	International Business Machines Corporation (IBM)
Type	Professional Computer
Release date	April 1987; 29 years ago (1987-04)
Predecessor	IBM Personal Computer/AT
Successor	IBM PC Series

The Personal System/2 or PS/2 was IBM's third generation of personal computers. Released in 1987, it officially replaced the IBM PC, XT, AT, and PC Convertible in IBM's lineup.

The PS/2 line was created by IBM in an attempt to recapture control of the PC market by introducing an advanced yet proprietary architecture. IBM's considerable market presence plus the reliability of the PS/2 ensured that the systems would sell in relatively large numbers, especially to large businesses. However the other major manufacturers balked at IBM's licensing terms to develop and sell compatible hardware, particularly as the demanded royalties were on a per machine basis. Also the evolving Wintel architecture was seeing a period of dramatic reductions in price, and so these developments prevented the PS/2 from returning control of the PC market to IBM.

However, many of the PS/2's innovations, such as the 16550 UART (serial port), 1.44 MB 3.5-inch floppy disk format, 72-pin SIMMs, the PS/2 keyboard and mouse ports, and the VGA video standard, went on to become standards in the broader PC market.

The OS/2 operating system was announced at the same time as the PS/2 line and was intended to be the primary operating system for models with Intel 286 or later processors. However, at the time of the first shipments, only PC DOS was available. OS/2 1.0 (text-mode only) and Microsoft's Windows 2.0 became available several months later. IBM also released AIX PS/2, a UNIX operating system for PS/2 models with Intel 386 or later processors.