This project allows you to test a Z80 CPU.
It tries
- to identify the CPU technology (NMOS/CMOS),
- to identify the CPU manufacturer,
- to test whether the CPU is still functional,
and helps
- to find out the max. supported clock rate.
The above results will help to identify fake CPUs.
It does not test
- Interrupts
- WAIT and HALT inputs signals
- M1 and RFSH output signals
- BUSRQ and BUSACK signals
The hardware has following features:
- 32kb EPROM (27C256), alternatively an EEPROM can be used (AT29C256)
- 32kb SRAM
- 2 output ports (1x unidirectional, 1x read-back) with 16 LEDs
- RESET and NMI button
- 16 MHz / 20 MHz switchable
- 1, 1/2, 1/4, 1/8, 1/16 multiplicator (1-16 MHz / 1.25-20 MHz)
- Connectors for measuring CPU power consumption
- USB powered
- THT for easy soldering
This project is based on an idea of
- https://oshwlab.com/vitalian1980/z80-tester (Hardware, Public Domain)
and additionally based on ideas of
- https://bitbucket.org/rudolff/z80-tester (Software, No license)
- https://github.com/djtersteegc/z80-cmos-nmos-tester (MIT license)
- https://github.com/skiselev/z80-tests (Software, GPL-3.0 license)
- https://github.com/EtchedPixels/FUZIX/blob/master/Applications/util/cpuinfo-z80.S (Software, GPL-2.0 license)
- https://groups.google.com/g/retro-comp/c/rhKeKpXmAXM (Software)
- https://www.malinov.com/sergeys-blog/z80-type-detection.html
and finally Frank Cringle's Z80 instruction set exerciser
- https://github.com/begoon/z80exer (Software, GPL-2.0 license)
[Please check the licence files in the relevant directories. When you are interested in a PCB, please contact me.]
The project uses KiCAD and zmac.
Zilog Z84C0020PEC from a Chinese marketplace. It is a U880 (running with 10 MHz):
