Systems Architecture

Question 1

What does ‘CPU’ stand for

Answer 1

Central Processing Unit

Question 2

What is the purpose of the CPU

Answer 2

To process data and instructions by constantly repeating the fetch-execute cycle

Question 3

What are the 4 main components of the CPU

Answer 3

CU, ALU, Registers and cache

Question 4

Describe the purpose of the CU

Answer 4

The Control Unit sends control signals to direct the operation of the CPU (in the ALU and RAM). It also decodes instructions as part of the fetch-execute cycle

Question 5

Describe the purpose of the ALU

Answer 5

The Arithmetic Logic Unit performs simple calculations and logical operations

Question 6

Describe the purpose of the Registers

Answer 6

The registers are temporary storage space for one instruction or address which are used during the fetch-execute cycle

Question 7

Describe the purpose of Cache

Answer 7

Cache memory is used to store data that is frequently accessed

Question 8

What is the key feature of Von Neumann Architecture

Answer 8

A computer stores both program instructions and data in the same memory (RAM)

Question 9

Describe the purpose of the PC

Answer 9

The program counter tracks the RAM address of the next instruction to be fetched

Question 10

Describe the purpose of the ACC

Answer 10

The accumulator stores the result of mathematical or logical calculations

Question 11

Describe the purpose of MAR

Answer 11

The memory address register tracks the RAM address of the instruction that is to be fetched.

Question 12

Describe the purpose of MDR

Answer 12

The memory data register stores the instruction that has been transferred from RAM to the CPU

Question 13

What happens during the fetch-execute cycle

Answer 13

The PC displays the address of the next instruction to be fetched into RAM which is then copied to the MAR. The PC is incremented where is prepares the CPU for the next instruction to be fetched. The CPU checks the address in RAM matches the MAR. Instruction in MAR is then copied to the MDR and then ALU. It is then decoded and executed where the results are stored in the ACC

Question 14

What is Cache Memory

Answer 14

Temporary storage for frequently accessed data

Question 15

How does Cache improve the performance of the CPU

Answer 15

Cache is closer to the CPU than RAM so it provides data and instructions at a faster rate. More cache means computers can store instructions faster

Question 16

Why do most computers have little Cache

Answer 16

Cache can be costly

Question 17

What is Clock speed and what is it measured in

Answer 17

Clock speed is a measure of how quickly a CPU can process instructions and it is measured in gHz (3.5gHz is equal to 3.5billion cycles per second)

Question 18

How does higher clock speed improve the CPU performance

Answer 18

More quick to perform the fetch-execute cycle resulting in better performance as more instructions are processed each second

Question 19

How does ‘overclocking’ and ‘underclocking’ affect the performance of the CPU

Answer 19

Overclocking: Higher than the recommended rate, which can lead to overheating
Underclocking: Lower than the recommended rate, making it slower but increase the lifespan

Question 20

What is a Core

Answer 20

A complete set of CPU components where each component can perform its own fetch-execute cycle.

Question 21

Why would a quad core processor have a higher performance than a dual core processor

Answer 21

A dual: 2 instructions simultaneously
A quad: 4 instructions simultaneously

Question 22

Why might having multiple cores doesn’t necessarily mean the CPU performance will be better

Answer 22

If one core is waiting for another to finish, performance may not increase at all.

Question 23

What is an embedded system

Answer 23

A computer built into a larger machine to provide a means of control because a specific pre-programmed task is stored in the ROM

Question 24

List some examples of embedded systems

Answer 24

Microwave, washing machine, traffic lights