There are some new USB keyboards, that behave like a ps/2 keyboard, using the old protocol, if the data+, and the data- lines are pulled up. I have one of these.
I start the board doing the circuit for a 6502 cpu proposed by Ben Eater in the following video, but in the middle I of the process i found the ps/2 keyboard schematic for a z80 available in the cpuville website.
The software for a 6502 is described in the following video (i did not follow the software video).
Then I decide to do a mix from both circuits, and my own view of the enable output logic for the shift registers. From the Ben Eater I retain the interrupt generation, and the inverter on the clock.
From cpuville I use the interaction concept. One port for reading LSB, and reset the shift registers, and another por to reading the MSB. I also use the main clock to update the output register of the shifters, instead the signal used as interrupt, and invert the data.
The circuit was build in a breadboard, and some software was done to check if it is working good.
Software used in tests:
The interface seems to work good. Need to improve the software, and later try include it in the small computer monitor.