The layout of this keyboard is the basis for what most people would consider to be a 'standard' layout for a full size keyboard. VariantsThe very first Model M's were of the AT variety they had 101 keys and a detachable cable with a 5 pin DIN connector. IBM PS/2 Keyboard (1987) - Compatible with AT systems, not compatible Uses what we now refer to as scan code set 2.IBM AT Keyboard (1984) - Not backward compatible with XT systems. Uses what we now refer to as scan code set 1.Remain backward compatible.) Below is a summary of IBM's three major The additional features ever caught on (since software also wanted to Nonetheless, it remained backward compatible with AT systems and few of Used a smaller connector and supported a few additional features. Keyboards and PS/2 keyboards were very similar devices, but the PS/2 device The keyboards we use today, and are the topic of this article. Next came the IBM AT system and later the IBM PS/2. The original IBM PC, and later the IBM XT, used what weĬall the 'XT keyboard.' These are obsolete and differ significantlyįrom modern keyboards the XT keyboard is not covered in this article. IBM introduced a new keyboard with each of its major desktop computer Even though they all use the same protocol, there are different variants, and in order to properly interface with a Model M, it is germane to understand their history. HistoryEvery Model M keyboard uses the PS/2 keyboard protocol - the Model M is in fact the original PS/2 keyboard.

Usb to ps2 converter protocol