Sometimes it’s apparent that there is no practical use for
something featured on Hack a Day, but we don’t know if [Andrew
Filer]‘s Apple ][ USB keyboard qualifies for this. After reading
through the very thorough documentation available in electronic
and dead tree formats, [Andrew] decided that Apple ][ would make
a great USB keyboard. Unlike modern keyboards, vintage computers
like the TRS-80, Commodore 64, and the Apple ][ return the 7-bit
ASCII value of the key instead of a scan code. The ASCII codes
generated by the keyboard were sent through a Teensyduino
running [Andrew]‘s keyduino sketch. Modern PS/2 keyboards use
MAKE and BREAK scan codes sent from a microcontroller that reads
the keyboard matrix. For example the MAKE code for the letter
‘A’ is 1C, while the BREAK code is F0 1C. There is a reason for
this design, but for the DIYer, interfacing a keyboard becomes a
challenge without a separate microcontroller. We’re thinking
[Andrew]‘s keyduino could be a great way to put a keyboard in a
project, but w