Keyboard input and RAM disks make CP/M more useful Wednesday, 16th June 2010

The hardware for the computer has changed in (mostly) subtle ways since the last post, with the exception of a PS/2 socket for connection to a keyboard. PS/2 keyboards (which use the same protocol as the older AT keyboard) communicate with the host by clocking data in either direction (keyboard to host or host to keyboard) over two wires, appropriately named "clock" and "data". An AVR pin change interrupt is used to detect a change in state of the clock line and either input or output a bit on the data line depending on the current direction of data transmission.

Comments ATmega644P AVR CP/M Electronics Keyboard Z80 Z80 computer