1.1.1 Structure of the CPU

Question 1

ALU

Answer 1

The ALU performs all of the arithmetic and logical
operations of the CPU, including: Addition and subtraction, multiplication and division. Comparisons such as whether numbers are equal or if one is greater than another. Boolean operations such as AND, OR and NOT.

Question 2

Control Unit

Answer 2

Sends out control signals to other parts of the CPU. Executes program instructions by following the fetch-decode-execute cycle.

Made up of two key parts: The Clock - coordinates CPUs activity. The Decoder - Decodes program instructions.

Question 3

Registers

Answer 3

Registers are tiny amounts of super-quick memory within the CPU. Used to hold information needed for the CPU to work. Each register holds a specific piece of information.

Question 4

MDR

Answer 4

Holds the data that has been retrieved from memory, or that is about to be stored in memory.

Question 5

MAR

Answer 5

Holds the address of the location in memory where data is to be retrieved or stored.

Question 6

CIR

Answer 6

The Current Instruction Register (CIR) is used to store the current instruction that the CPU is working on.

Question 7

PC

Answer 7

Holds the memory location address of the next instruction to be performed by the CPU. The PC does not store the instruction itself.

Question 8

Accumulator

Answer 8

Holds the result of calculations and operations performed by the arithmetic logic unit (ALU).

Question 9

Buses

Answer 9

Buses are used to send and receive data and instructions from main memory (RAM).

Question 10

Control Bus

Answer 10

The control bus sends control signals to other devices inside the computer system.

Question 11

Address Bus

Answer 11

The address bus sends addresses to the main memory.

Question 12

Data Bus

Answer 12

The data bus retrieves data and instructions from main memory.