Zexall

ZEXALL is a software test for the Zilog Z80 microprocessor , created by Frank Cringle in 1994 . Often used by creators of emulators to verify the correct implementation of the emulation of this processor.

The test is part of the distribution of the Z80 processor emulator, distributed as source code - YAZE (Yet Another Z80 Emulator). The test itself is called Z80 Exerciser (shortened to ZEX), and exists in two versions: ZEXDOC tests only documented flags; ZEXALL tests all flags, including undocumented ones. Also supplied as source code. There are adaptations of the test for various assemblers for the Z80, and computers based on this processor.

The testing algorithm is based on the execution of certain instructions, or a group of instructions of the same type, with some input data. The result of the execution of each type of instruction is accumulated in the form of a 32-bit checksum , after which it is compared with the value obtained empirically by a real and obviously working Z80 processor.