I have been looking more into how CPU's work, and have a question. If I have a instruction that e.g. takes a 64bit address and a register, and copies the value from that address into the register. And that instruction has a 2 byte opcode. Then let's say the entire instruction is 80 bits in size.(8 bytes) Then how would it execute that instruction? Since I presume it doesn't fit in the instruction register(because the register is 64 bits). Does it just take the opcode and fetch the address(and later it's value) and register later? Or does it have multiple registers? Or does it have one mega big instruction register to fit it all?