Category: Science & Technology Key figures: IBM PC Company (developer), Bill Lowe (IBM executive who oversaw the original PC), Don Estridge (IBM PC architect, died 1985), Compaq and nine OEMs who formed the EISA consortium in response
On April 2, 1987, IBM introduced the Personal System/2 (PS/2) line of personal computers, its most ambitious attempt to reclaim control of the PC market it had inadvertently created in 1981. The launch comprised four models — the Model 30 (8 MHz 8086, $1,695), Model 50 (10 MHz 80286), Model 60 (10 MHz 80286), and Model 80 (20 MHz 80386, $10,895) — along with a simultaneous release of the OS/2 operating system co-developed with Microsoft. An all-in-one Model 25 followed in August 1987 at $2,595.
The PS/2 line introduced or standardized several technologies that would persist as industry standards for decades, even as the machines themselves failed commercially:
Micro Channel Architecture (MCA): IBM’s proprietary 32-bit bus replaced the ISA (Industry Standard Architecture) bus used by all IBM-compatible clones. MCA was technically superior — it supported bus mastering, auto-configuration, and higher bandwidth — but it was incompatible with existing ISA expansion cards and required clone manufacturers to pay IBM licensing fees. This was IBM’s core strategic gambit: by making the bus proprietary, IBM hoped to force the clone industry into financial dependence.
VGA (Video Graphics Array): The PS/2 replaced the Enhanced Graphics Adapter (EGA) with VGA, which offered 640×480 resolution at 16 colors or 320×200 resolution at 256 colors. VGA’s analog signal standard and the accompanying HD-15 (“VGA connector”) became the universal PC display interface for more than two decades.
PS/2 Ports: A new 6-pin mini-DIN connector replaced the larger 5-pin DIN standard for keyboards and introduced a dedicated mouse port, eliminating the need for serial-port mice. The PS/2 keyboard and mouse port standard would remain dominant until the adoption of USB peripherals in the early 2000s.
3.5-inch Floppy Drives: The PS/2 standardized the 3.5-inch floppy disk — available in 720 KB (double-density) and 1.44 MB (high-density) formats — displacing the fragile 5.25-inch format across the industry.
72-pin SIMMs: A new RAM module form factor that became the dominant memory standard for PC desktops through the mid-1990s.
IBM’s strategy backfired. Nine leading PC manufacturers — Compaq, HP, AST Research, Epson, NEC, Olivetti, Tandy, Wyse, and Zenith — refused to license MCA and in September 1988 formed the EISA (Extended Industry Standard Architecture) consortium, releasing a competing 32-bit extension of the ISA bus that preserved backward compatibility. The consumer market, unwilling to pay PS/2 price premiums and unable to reuse existing ISA cards, sided with the clones. Though IBM sold approximately three million PS/2 units by September 1988, primarily to corporate clients, market leadership in personal computing shifted irreversibly to Compaq, which had already shipped a 386-based machine in 1986, and eventually to Dell and other clone-makers.
The OS/2 operating system launched alongside the PS/2 was adopted by few consumers; most PS/2 buyers continued running MS-DOS, and OS/2 never achieved the market share IBM and Microsoft had envisioned before the partnership dissolved in 1990.
The IBM PS/2 launch of 1987 represents a pivotal inflection point in the history of the personal computer industry. IBM had created the open-architecture PC standard in 1981, inadvertently enabling the clone market that by 1987 had eroded its dominance. The PS/2 was IBM’s attempt to close the architecture with proprietary technology — and the industry’s rejection of that attempt effectively confirmed that the PC standard now belonged to the clone ecosystem rather than to IBM.
The enduring legacy of the PS/2 lies in its successful standards: VGA remained the universal PC display connector until the HDMI and DisplayPort era; PS/2 keyboard and mouse ports persisted on motherboards through the 2010s; 3.5-inch floppies were standard removable media until USB drives supplanted them; and 72-pin SIMMs dominated desktop memory through Windows 95 and 98. IBM had lost control of its market while simultaneously setting the hardware baseline its competitors would build upon for the next fifteen years.