Editing IBM PS/2 (section)

===Keyboard/mouse===

====Layout====
The PS/2 IBM [[Model M keyboard]] used the same 101-key layout of the previous [[IBM PC/AT]] Extended keyboard.{{r|byte198706}}  European variants had 102 keys with the addition of an extra key to the right of the left Shift key.

====Interface====
{{further|PS/2 port}}
[[Image:IBM PS2 hiiri.jpg|upright|thumb|left|The original IBM PS/2 mouse]]
[[Image:ps-2-ports.jpg|thumb|right|PS/2 connection ports (later colored purple for keyboard and green for mouse, according to [[PC 97]]) were once commonly used for connecting input devices.]]

PS/2 systems introduced a new specification for the [[Computer keyboard|keyboard]] and [[computer mouse|mouse]] interfaces, which are still in use today{{Citation needed|date=March 2025|reason=This might have been true a decade ago, but practically no new peripherals uses these interfaces, and very little (newly manufactured) computer hardware even has the physical connectors.}} (though increasingly supplanted by [[USB]] devices) and are thus called "PS/2" interfaces. The PS/2 keyboard interface, inspired by Apple's ADB interface, was electronically identical to the long-established [[AT Keyboard|AT]] interface, but the cable connector was changed from the 5-pin [[DIN connector]] to the smaller 6-pin [[Mini-DIN connector|mini-DIN]] interface. The same connector and a similar synchronous serial interface was used for the PS/2 mouse port.

The initial desktop ''[[IBM PS/2 Model 50|Model 50]]'' and ''[[IBM PS/2 Model 60|Model 60]]'' also featured a new cableless internal design, based on use of interposer circuit boards to link the internal drives to the planar (motherboard). Additionally, these machines could be largely disassembled and reassembled for service without tools.

Additionally, the PS/2 introduced a new software data area known as the [[Extended BIOS Data Area]] (EBDA). Its primary use was to add a new buffer area for the dedicated mouse port. This also required making a change to the "traditional" [[BIOS Data Area]] (BDA) which was then required to point to the base address of the EBDA.

Another new PS/2 innovation was the introduction of bidirectional [[parallel port]]s which, in addition to their traditional use for connecting a printer, could now function as a high-speed data transfer interface. This allowed the use of new hardware such as parallel port [[Image scanner|scanner]]s, CD-ROM drives, and also enhanced the capabilities of printers by allowing them to communicate with the host PC and send back signals instead of simply being a passive output device.