Model F keyboard

The Model F was a series of computer keyboards produced from 1981–1994 by IBM and later Lexmark. Its mechanical-key design consisted of a buckling spring over a capacitive PCB, similarly to the later Model M that used a membrane in place of the PCB.

The Model F first appeared with the IBM System/23 Datamaster all-in-one computer. It is best known as part of the IBM Personal Computer in 1981 with some keycap label differences, and its subsequent release with the IBM 5170, where it was reconfigured with the AT protocol and some layout revisions.