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PS/2: Difference between revisions
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PS/2 is a type of serial communication, typically used for user input devices (keyboard, mouse, bar code scanner, etc). It involves a controller (e.g. "8042 chip" on PC compatible systems), the mechanical and electrical details of the communication itself, and a device.
Originally (1981) IBM used a different type of serial communication for XT keyboards. The older interface was not bi-directional - the device could talk to the controller, but the controller couldn't talk to the device.
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Eventually the PS/2 was superseded by USB, however it is still fairly common (and for compatibility, some system have emulation layers that make USB devices appear as PS/2 devices).
==
A diagram of the PS2 connector is below.
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* 1 acknowledgement bit
== Driver Model ==
There are various types of PS/2 port controllers; including "bit banging" general purpose IO, special support built into the system's chipset and add-on PCI cards. There are also various types of PS/2 devices (keyboard, mouse, touch-pad, bar code scanner, magnetic card/stripe reader, fingerprint reader, etc).
Obviously you don't want to duplicate the code for every type of PS/2 device within each different PS/2 controller driver. You want to separate them, so that any driver for a PS/2 device can talk to any PS/2 controller driver (and so that the PS/2 device's code can be ported to different architectures without any changes). This is relatively simple to do - PS/2 controller drivers only need to be able to send and receive bytes (there's no baud rate control or anything) and a simple "byte stream" approach suffices.
==See Also==▼
▲== See Also ==
=== Articles ===
*[["8042" PS/2 Controller]]▼
*[[PL050 PS/2 Controller|PL050 PS/2 Controller (ARM)]]
*[[PS/2 Keyboard]]
*[[PS/2 Mouse]]
▲*[["8042" PS/2 Controller]]
=== External Links ===
*[http://www.versalent.biz/ps2facts.htm PS2 Facts and Info from Versalent]
*[
[[Category:Common Devices]]
[[Category:Hardware Interfaces]]
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