The Processor

Question 1

Purpose of the CPU

Answer 1

• To process machine instructions
• Carry out the fetch-decode-execute cycle

Question 2

3 Main components of CPU

Answer 2

CU, ALU, RAM

Question 3

What is the CU?

Answer 3

Control Unit: Sends control signals to other components - responsible for organising the FDE of instructions

Question 4

What is the ALU?

Answer 4

Performs calculations and makes logical decisions

Question 5

What is RAM?

Answer 5

Holds the data and instructions for the currently running programs

Question 6

What are registers?

Answer 6

Stores the programs which are needed instantly e.g. software applications

Question 7

5 registers

Answer 7

1) Accumulator
2) PC
3) CIR
4) MDR
5) MAR

Question 8

Accumulator

Answer 8

Holds the data currently being processed

Question 9

Program Counter

Answer 9

Holds the memory address of the next instruction to be executed

Question 10

Current Instruction Register

Answer 10

Stores the address of the instruction currently being executed

Question 11

Memory Data Register

Answer 11

Stores data being transferred temporarily

Question 12

Memory Address Register

Answer 12

Stores the address of the memory location currently in use

Question 13

Address Bus

Answer 13

Carries the address of the memory locations

Question 14

Data Bus

Answer 14

The contents of the instruction are carried

Question 15

Control Bus

Answer 15

Informs whether the info is read or write control signals

Question 16

Bus Width

Answer 16

The number of wires that make up a bus - determines the range of instructions that can be transmitted

Question 17

Fetch Stage

Answer 17

• PC register displays the address in RAM of the next instruction to be processed
• This value is copied into the MAR
• The PC is incremented by 1
• This prepares the CPU for the next instruction to be fetched
• The CPU checks the address in RAM which matches the address held in the MAR
• The instruction in RAM is transferred to the MDR
• The instruction in the MDR is copied into the CIR

Question 18

Decode Stage

Answer 18

The instruction in the CIR is understood and decoded

Question 19

Execute Stage

Answer 19

Any result of an execution is stored in the ACC register

Question 20

Clock Speed

Answer 20

How many CPU cycles can be run per second - the bigger the number the more cycles can be run per second

Question 21

Overclocking

Answer 21

Making a computer or component operate faster than the clock frequency specified by the manufacturer - system can become unstable and there is a risk of damage due to excessive heat generation

Question 22

Cache

Answer 22

Cache memory is used as the RAM is significantly slower than the speed CPUs operate - fast memory built into the processor reducing the distance data has to travel to it

Question 23

Cores

Answer 23

Additional processors

Question 24

Increasing the number of cores

Answer 24

Ensures cycles can be run simultaneously

Question 25

Increasing cache size

Answer 25

Ensures more frequently used programs can be accessed much faster