You see them all the time from fresh faced EE students looking to power their new arduinos and LED’s. The simple computer power supply hacked and forged into a fixed output power supply for a range of very common voltages. Which is exactly why I did the same thing. I like my design, rather than trying to cram it all into the PSU case I attached a piece of bent Lexan to the underside of the case and brought all the wires out.
Yesterday I went to my local Hamfest and picked up a few Z80 Processors and other goodies. While reading the datasheet I noticed something. If the data lines for the z80 are held in an active low state I will send the CPU a series of NOP (No-Operation) commands. A quick glance on the internet confirmed this and I quickly breadboarded a prototype. I used a manual pulsar as the clock source, tied data lines down and sent the four least significant bits of the address lines out to some LED’s.