**The CALL cc,nn instruction has an extra T-state inserted in M3 depending if cc is true or not.
Every place the Z80 manual shows a memory read taking more than 3 clocks, or an opcode fetch/decode taking more than 4 clocks, it should be interpreted as "standard read or fetch cycle with (n - 3) or (n - 4) internal operations after". [https://forums.nesdev.org/viewtopic.php?p=179001#p179001 Source]
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