In the process of debugging a PS/2 keyboard controller prototype for the spectrum (well, pentagon), I made a simple keyboard tester utility. It builds as a ROM (which was useful in my case as the jumper-selectable second ROM of the pentagon, since I didn't have a keyboard to load it regularly), or as a tape file. Released it as public domain, in case it's useful to other people too. It really helped me figure out what was going wrong with my design :)
http://nuclear.mutantstargoat.com/sw/zxkeybtest/
Keyboard tester program (ROM/TAP)
Keyboard tester program (ROM/TAP)
John Tsiombikas (Nuclear / Mindlapse & The Lab)
http://nuclear.mutantstargoat.com
http://nuclear.mutantstargoat.com