A Z80 test-program for ZX Spectrum Computer can be found under: https://github.com/raxoft/z80test
which performs 152 Tests on Z80-Emulation.
MAME 0.227 fails on two of these tests, as can be read here: https://spectrumcomputing.co.uk/forums/ ... 361#p56361
Maybe someone from the MAMEDEV-Team want to look, why those tests fail.