1.1.1 Structure and function of the processor

Question 1

What does CPU stand for?

Answer 1

Central Processing Unit

Question 2

What is the CPU?

Answer 2

The main chip on the computer which contains many components that allow it to carry out its function of executing instructions.

Question 3

What components make up the CPU?

Answer 3

Control Unit (CU).
Arithmetic Logic Unit (ALU).
Registers.
Busses.

Question 4

What is the role of the Control unit (CU)

Answer 4

Coordinate the activities of the CPU (the Fetch Decode Execute cycle). It accepts instructions and decodes them into steps. It then sends these commands throughout the CPU.

Question 5

What is the role of the Arithmetic Logic Unit (ALU)?

Answer 5

To perform arithmetic and logical operations on the data. It performs ADD, SUBTRACT, MULTIPLY and DIVIDE. It can perform shift operations as well as Boolean logic - AND, OR, NOT and XOR.
Full Adders live here and results from the ALU are passed to the accumulator.

Question 6

What are the registers in the CPU?

Answer 6

Program Counter (PC).
Current Instruction Register (CIR).
Memory Address Register (MAR).
Memory Data Register (MDR).
Accumulator(Acc).

Question 7

What is the role of the Program Counter (PC)?

Answer 7

Holds the address of the next instruction to be executed. It is incremented by one part way through the FDE cycle. Or changed if the instruction is to jump to another location in memory - this is copied from the Current Instruction Register (CIR).