What is it?

Used Z80 processors can be purchased for a low cost from China, sold as CMOS 8MHz Z84C0008PEC but most of them are re-labelled NMOS or CMOS chips from different vendors and speed grade.

This CPU tester has simple software in external EEPROM. It uses undocumented instruction OUT (C), 0 which behaves as OUT (C), $ FF on CMOS Z80s. The actual CMOS or NMOS CPU version is shown by the corresponding LED. There is continuous running light "Kit effect" on P0-P7 LEDs to check CPU functionality at specific clock speed. The clock speed is selectable by DIP switch between 1MHz, 2MHz, 4MHz and 8MHz.

You can write your own software to extend tester functionality or modify existing one. P0-P7 LEDs are accessible on I / O port address $ 00, NMOS / CMOS LEDs on address $ 01.

Supplied without USB mini cable.