Hi, this is my own "interpretation" of the retro computing theme.
This thing uses an Atmega32A with an Arduino bootoader as universal I/O subsystem, "emulating" the I/O ports seen by the Z80, and the ROM too.
And with the cost of only 4$ (buying components from ebay...) it is possible to taste some flavor of retro computing...
Here is a short video:
Here all the details of the whole thing: https://hackaday.io/project/19000-a-4-4ics-z80-homemade-computer-on-breadboard