* If the next byte is a DD, '''ED''' or FD prefix, the current DD or FD prefix is ignored (it's equivalent to a NONI) and processing continues with the next byte. ED-prefixed opcodes cannot be altered by DD or FD prefixes.
When a DD or FD prefix is followed by a CB byte, the CB acts as a second prefix. A mandatory displacement byte comes next, and then the actual opcode. If the instruction produces output other than in the flags (i.e. all except BIT), then the result gets placed both into (IX+d) or (IY+d) and the register one would normally expect to be altered.
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