Model M keyboard

Model M keyboards are a group of computer keyboards designed and manufactured by IBM starting in 1985, and later by Lexmark International, Maxi Switch, and Unicomp. The keyboard's different variations have their own distinct characteristics, with the vast majority having a buckling-spring key design and uniform profile, swappable keycaps. Model M keyboards are notable among computer enthusiasts and frequent typists due to their durability, typing-feel consistency, and their tactile and auditory feedback. The popularity of the IBM PC and its successors made the Model M's design influential: Almost all later general-purpose computer keyboards mimicked its key layout and other aspects of its ergonomics. The layout was standardized by ANSI in 1988 and ISO in 1994. Later versions of their standards specified or provisioned for minor additions—most notably the Windows key and Menu key. The Model M is regarded as a classic and durable piece of hardware. Although the computers and computer peripherals produced concurrently with them are considered obsolete, many Model M keyboards are still in use due to their physical durability and the continued validity of their ANSI 101-key and ISO 102-key layouts, through the use of a PS/2-female-to-USB-male adapter with a built-in interface converter. Since their original popularity, new generations have discovered their unique functionality and aesthetics. It is estimated that during the IBM and Lexmark years, over 10 million Model Ms were shipped. Their mass-market success ended in the 1990s amid an industry-wide switchover to lower-cost rubber dome over membrane keyboards. IBM stopped producing the Model M keyboard in 1996.