This is my “real” Z80 computer (the Z180 is close, but not quite the real thing…).
This is another excellent DIY-kit from Stephen C. Cousins, the SC114 Z80 Motherboard. The CPU is a standard Z80 clocked at 7.4 MHz.
I have added an extra module, an SC132 with the Z80 SIO (ZiLOG PDF documentation) for high-speed serial communications at 115200 baud. This module is not a requirement, the SC114 also runs standalone at 9600 baud from the FTDI connector on the motherboard.
To the far right, I have setup a Raspberry Pi Zero W to use as a frontend terminal.
NEVER connect 5 volt TTL output to a Raspberry Pi GPIO input! They are NOT 5V tolerant, they are specified for max 3.3 volt. Use a level shifter or a voltage divider to protect your Pi.
Having said that, I actually ran this setup for months without knowing, and I haven’t fried a Pi (yet). Reading about the risk of destroying the Pi, I decided not to try this with any Pi in the future, and I now use very cheap level shifters which work fine. If (like me) you never heard of level shifters/converters before, you may read this guide about level shifters.
For power to the SC114, I connect ground and 5 Volts to get power supply from the Pi to the SC114/SC132. To be honest, I am not really sure if this is “healthy” but I guess the SC114 does not draw that much current anyway.
It’s a fun fact that the Pi runs at a clock speed more than a 100 times faster than the Z80, and has about 8000 times the memory capacity! Nevertheless, whole businesses could run their IT on Z80 computers with CP/M a few years ago… or, to be honest, many years ago.
The SC114 can be expanded to run the CP/M 2.2 operating system, see Z80 Computer SC114 with CP/M 2.2.
