Control unit, Arithmetic logic unit and special purpose registers

Question 1

What does the control unit do in the CPU?

Answer 1

It coordinates all the activities taking place in the CPU

Question 2

Summarise the control units functions.

Answer 2

[]it controls the execution of instructions in the correct sequence
[]it decodes instruction
[]it regulates and controls processor timing using regular pulses from the system clock
[]it send and receives control signals to and from other devices within the computer

Question 3

What functions does the ALU carry out ?

Answer 3

[]logical operations - these include AND, OR and NOT
[]Shift operations - The bits in a computer word can be shifted left or right by a certain number of places
[]Arithmetic operations - These include additions, subtraction, multiplication and division.

Question 4

What is a register?

Answer 4

A register is a special very fast memory location within the CPU used in the execution of instructions.

Question 5

Name and explain each special register in a register?

Answer 5

The memory address register (MAR) holds the address  of the instruction or piece of data to be fetched or stored.
The memory data register (MDR) holds data or a program instruction temporarily when it is fetched from memory or it is sent to memory.
The program counter (PC) holds the memory address of the next instruction to be processed.
The accumulator (ACC) is a special-purpose, memory location in which results of operations carried out in the ALU are temporarily stored.

Question 6

What does MAR stand for?

Answer 6

Memory Address Register

Question 7

What does MDR stand for?

Answer 7

Memory Data Register

Question 8

What does PC stand for?

Answer 8

Program counter

Question 9

What does ACC stand for?

Answer 9

The Accumulator

Question 10

What does the MAR do?

Answer 10

It holds the address of the instruction of piece of data to be fetched or stored

Question 11

What does the MDR do?

Answer 11

It holds data or a program instruction temporarily when it is fetched from memory or be sent to memory.

Question 12

What does the program counter do?

Answer 12

It holds the memory address of the next instruction to be processed

Question 13

What does the Accumulator do?

Answer 13

It is a special-purpose memory location in which results of operations carried out in the ALU are temporarily stored

Question 14

What is the address in a computer?

Answer 14

Location in the memory?