$3$

system bus

opcode

$2$

program counter

D flip$-$flop

control unit

instruction set architecture

specifies the instructions that the computer

can perform

group of bits that tells the computer to

perform an operation

keeps track of the next instruction to be

fetched

holds the address of the data to be

transferred

holds the actual data to be read from or

written

can cause throughput delays

carries out program instructions