IFF2 stores the previous state of IFF1 so that after the NMI is handled, IFF1 can be restored to its original state.
On a A barebone Amstrad CPC, doesn't use NMI is not used. So IFF1 and IFF2 values are always identicalthe same. However, NMI is used by the [[PlayCity]] and [[Play2CPC]] expansions.
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| WZ || 16-bit || Internal temporary register pair. Also known as MEMPTR || Used for memory and address calculations.