Changes
Z80
,/* Chip Variants */
* The Nintendo documentation doesn't mention M-cycles or T-states at all. They only mention CPU cycles, which are the equivalent of NOPs in the CPC world. Also, the GBZ80 has different timings than the Z80. For example, CALL nn takes 6 cycles for the GBZ80, but only 5 NOPs for the Z80. [https://archive.org/details/GameBoyProgManVer1.1/ Gameboy programming manual]
* The GBZ80 lacks the alternate register set, the dedicated I/O bus, the NMI pin, the IM instructions, the I and R registers, the index registers (DD and FD prefixed opcodes are missing), the ED prefixed opcodes (including block transfer), the sign and parity/overflow flags (and all conditional instructions that used them), the undocumented flags (thus no leaking of WZ and Q internal registers). [https://www.pastraiser.com/cpu/gameboy/gameboy_opcodes.html GBZ80 opcodes]
* Fun fact: Way more GBZ80 cores were produced for Gameboy hardware (118 million Gameboys and 81 million GBA) than all the Z80 chips produced for home computers and game consoles. [https://www.chibiakumas.com/z80/Gameboy.php Learn GBZ80 Assembly Programming with ChibiAkumas]
