A barebone Amstrad CPC doesn't use NMI. So IFF1 and IFF2 are always the same. However, NMI is used by some expansions.
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| HALT || 1-bit || HALT state || /HALT indicates that the CPU has executed a HALT instruction and is waiting for either an NMI or an IRQ (with IFF1 enabled) before operation can resume.
Each cycle in the HALT state is a normal M1 (fetch) cycle except that the data received from the memory is ignored and an NOP instruction is forced internally to the CPU.
The purpose of executing NOP instructions while in the HALT state is to keep the memory refresh signals active.
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| WZ || 16-bit || Internal temporary register pair. Also known as MEMPTR || Used for memory and address calculations.