The CPU (System Architecture)

Question 1

What 4 registers are in the CPU?

Answer 1

Program Counter (PC)
Memory Address Register (MAR)
Memory Data Register (MDR)
Accumulator

Question 2

What is a register?

Answer 2

A very fast memory location in the CPU

Question 3

What is cache?

Answer 3

It is slower to access than registers but faster than RAM

Question 4

Program Counter

Answer 4

Points to the next instruction that needs to be executed. Located in the Control Unit

Question 5

Memory Address Register

Answer 5

Holds the address of the current instruction and then the data that it uses so that these can be fetched from memory

Question 6

Memory Data Register

Answer 6

Holds the actual instruction and then the data that has been fetched from memory

Question 7

Accumulator

Answer 7

Holds the result of an instruction before it is transferred to memory

Question 8

Explain the Fetch-Decode-Execute cycle

Answer 8

Fetch - causes the next instruction and any data involved to be fetched from main memory

Decode - decodes instruction

Execute - the instruction is executed

Question 9

Arithemetic Logic Unit (ALU)

Answer 9

Performs calculations and logic expressions

Question 10

Control Unit

Answer 10

Co-ordinates the CPU activities