A deep-dive history marking 45 years since the IBM PC's launch on August 12, 1981, tracing the machine's lineage from the SCAMP prototype and 5100 through the System/23 Datamaster, and detailing the development and variants of the Model F/XT buckling-spring keyboard. Covers the PC's engineering choices (Intel 8088, ISA bus), the PC/XT, Portable PC, TEMPEST-hardened TPC variants, industrial and terminal keyboard offshoots (5291/5292, System 9000), and the keyboard's long production run through Lexmark into the mid-1990s.
Table of contents
ContentsIn the run upDatamasterPersonal Computer5291 & 5292System 9000Portable Personal ComputerTPC and EMRWhat about 5531?AcknowledgementsFurther reading & resourcesSourcesQuestions this post answers
What keyswitch technology did the original IBM PC keyboard use
The IBM Personal Computer keyboard, known as the Model F/XT, used capacitive buckling springs, a keyswitch design patented by Richard Hunter Haris. Pressing a key compresses a metal coil spring until it catastrophically buckles, pivoting a small capacitive plate over a capacitance-sensing PCB called a pad card, which detects the keypress. Collectors researching vintage keyboard mechanics can follow deep hardware history like this on daily.dev.
What is the difference between the Type 1 and Type 2 IBM Model F/XT keyboards
Type 1, the rarer original design seen only with '81 date codes, uses a 24x4 key matrix with a separate Intel 8048 controller daughterboard and a reset line, plus a DIN plug without a black plastic jacket. Type 2, found in nearly all surviving units and used exclusively by the time of the PC/XT, reverts to a 12x8 matrix, integrates the controller onto the pad card, drops the reset line, and adds a jacketed DIN plug. Anyone dating or restoring vintage IBM keyboards can track these hardware distinctions on daily.dev.
How long was the IBM 529X Model F keyboard produced
The 529X keyboard, used with the IBM 5291 and 5292 terminals, had the longest production run of any Model F variant. Lexmark, spun off from IBM's Information Products Corporation in March 1991, manufactured 529X keyboards into at least mid-1994 and continued refurbishing existing units through 1996, its final year in the keyboard business. Vintage keyboard collectors dating their finds can dig into production timelines like this on daily.dev.