Design an expanding OPCODE structure, for a processor to allow all the following to be encoded in a 24-bit instruction:
15 instructions with two 8-bit addresses and one 4- bit register number
150 instructions with one 8-bit address and one 4- bit register number
80 instructions with only one 8-bit = address field
Question: What would be the last OPCODE value in hex ? (hint: 4 hexadecimal digits)