| IR (Instruction Register) || 8-bit || Holds the opcode of the currently executing instruction || Internally used, not accessible by the programmer
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| EIP (Extended Instruction Prefix) || 2-bit || Stores Holds the prefix for extended instructions (CB, ED, or none) || Used for extended instruction sets like bitwise ops
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| IMP (Indexing Mode Prefix) || 2-bit || Specifies the indexing mode (DD for IX+d, FD for IY+d, or none for HL) || Indicates use of index registers (IX or IY) for memory access