ps/2 keyboard 동작

Heres a shot of my glorious hand-wired PS/2 keyboard connector. I spent some time over the weekend working out the details of how to read keyboard data. I came up with a solution that uses a 74LS161 to count the incoming bits, and a GAL to shift the bits into a byte, and signal a CPU interrupt once all the bytes have been read. It should be pretty simple to use in practice. At first I was worried that my CPU wouldnt be able to process interrupts from the keyboard quickly enough, and Id need to implement some kind of queue for incoming keyboard bytes. After doing some testing, though, it turns out that theres always at least 3 milliseconds between bytes, even for the bytes in a multi-byte scan code for a single keypress. Thats an eternity in computing terms

http://www.scienceprog.com/interfacing-pc-keyboard-to-avr-microcontroller/