A-level computer science - 1.1.1 CPU Structure and Function

What is the role of the ALU?

• Carries out calculations and logical operations

• Stores the most recently fetched instruction that is waiting to be decoded and executed

• Stores the data that has been fetched from or stored in memory

• Holds the address in memory of the next instruction to be fetched.

• Stores the address of the data or instructions that are to be fetched from or sent to

What is the role of the CIR?

• Carries out calculations and logical operations

• Stores the most recently fetched instruction that is waiting to be decoded and executed

• Stores the data that has been fetched from or stored in memory

• Holds the address in memory of the next instruction to be fetched.

• Stores the address of the data or instructions that are to be fetched from or sent to

What is the role of the MDR?

• Stores the results of calculations made by the ALU

• Stores the most recently fetched instruction that is waiting to be decoded and executed

• Stores the data that has been fetched from or stored in memory

• Holds the address in memory of the next instruction to be fetched.

• Stores the address of the data or instructions that are to be fetched from or sent to

What is the role of the PC?

• Stores the results of calculations made by the ALU

• Stores the most recently fetched instruction that is waiting to be decoded and executed

• Stores the data that has been fetched from or stored in memory

• Holds the address in memory of the next instruction to be fetched.

• Stores the address of the data or instructions that are to be fetched from or sent to

What is the role of the ACC?

• Stores the results of calculations made by the ALU

• Stores the most recently fetched instruction that is waiting to be decoded and executed

• Stores the data that has been fetched from or stored in memory

• Holds the address in memory of the next instruction to be fetched.

• Stores the address of the data or instructions that are to be fetched from or sent to

What is the role of the MAR?

• Stores the results of calculations made by the ALU

• Stores the most recently fetched instruction that is waiting to be decoded and executed

• Stores the data that has been fetched from or stored in memory

• Holds the address in memory of the next instruction to be fetched.

• Stores the address of the data or instructions that are to be fetched from or sent to memory

The most recently fetched instruction which is waiting to be decoded and executed is stored in the...

• MDR

• MAR

• CIR

• ACC

Data which has been fetched from or is to be stored in memory is held in...

• MDR

• MAR

• CIR

• ACC

The results of calculations made in the ALU are stored in the...

• MDR

• MAR

• CIR

• ACC

The addresses of data/instructions which are being sent to/from memory are stored in the...

• MDR

• MAR

• CIR

• ACC