1.1 Components of the CPU

Question 1

von Neumann architecture

Answer 1

the way in which the CPU is designed and carries out instructions with other components

in 1945 John von Neumann designed a stored program computer where both the program and data are stored in the memory

Question 2

components of the von Neumann architecture

Answer 2

• processing unit or CPU
• program counter
• memory
• input and output mechanisms

Question 3

CU

Answer 3

control unit

coordinates the actions of the computer

sends out control signals to other parts of the CPU and computer

control signals make everything happen inside the computer

Question 4

decoder

Answer 4

an important component of the CU

works out what the program instructions mean so control signals can be sent to other components that carry out the required actions

Question 5

ALU

Answer 5

arithmetic and logic unit

performs arithmetic and logical operations

• addition
• subtraction
• multiplication
• division
• comparisons between two different numbers

Question 6

MAR

Answer 6

memory address register

holds the address of the memory location currently being read or written to

(holds the location needed by the MDR)

Question 7

MDR

Answer 7

memory data register

a temporary store (buffer) for anything copied from memory

Question 8

PC

Answer 8

program counter

holds the address of the next instruction to be fetched

Question 9

ACC

Answer 9

accumulator

stores the results of calculations carried out by the ALU

Question 10

List two registers of the CPU with specific functions in the fetch-decode-execute cycle [2]

Answer 10

program counter

memory address register

etc.

Question 11

Describe the role of the control unit in the operation of the central processing unit [4]

Answer 11

the control unit coordinates the actions of the other components of the CPU and the whole computer by sending out control signals

it also decodes the program instructions and executes them using the other components