Computer Architecture

Question 1

Central Processing Unit

Answer 1

The CPU processes instructions and data that are input into the computer so that the result can be output

Question 2

Microprocessor

Answer 2

A type of integrated circuit on a single chip

Question 3

Stored-program concept

Answer 3

• Both data and instructions are stored in the same memory unit (RAM) as binary
• CPU uses the FDE cycle to execute instructions serially
• Programs can be moved to AND from the main memory

Question 4

Units in CPU

Answer 4

• arithmetic logic unit (ALU)
• control unit (CU)

Question 5

Registers in CPU

Answer 5

1. program counter (PC)
2. memory address register (MAR)
3. memory data register (MDR)
4. current instruction register (CIR)
5. accumulator (ACC)

Question 6

buses in CPU

Answer 6

• address bus
• data bus
• control bus

Question 7

Registers meaning

Answer 7

a type of small memory which holds data temporarily, to be processed.

Question 8

Program Counter function

Answer 8

stores the address of the next instruction to be fetched from memory.

Question 9

MAR function

Answer 9

Stores addresses of next instruction

Question 10

MDR

Answer 10

stores the data and instructions which has just been fetched from memory
or data which is to be written to memory

Question 11

CIR

Answer 11

stores the current instruction currently being decoded and executed

Question 12

ACC

Answer 12

temporarily stores the results of the calculations performed by the ALU

Question 13

Address Bus:

Answer 13

unidirectional- transmits addresses between components in the CPU

Question 14

Data Bus:

Answer 14

bidirectional- transmits data between components in the CPU

Question 15

Control Bus:

Answer 15

bidirectional- transmits control signals from the control unit to other components in the CPU

Question 16

CPU performance

Answer 16

• Core
• Cache
• Clock

Question 17

Core

Answer 17

• They process instructions.
• Each core performs separate FDE cycles independently from one another simultaneously, meaning parallel processing can take place.

More cores→ enables multitasking → more instructions executed simultaneously → faster and better performance.

• The more cores in the CPU, the better and faster the performance

Question 18

Cache characteristics

Answer 18

• Type of storage
• Used for storing frequently used instructions/data
• To speed up data access time
• Faster to access than RAM
• Has different levels e.g L1-L3
• Increasing the amount of cache→more data can be stored there→more data accessed faster→ improves performance.

Question 19

Clock Speed

Answer 19

the maximum number of FDE cycles a CPU can execute in a second

Question 20

Clock speed characterisics

Answer 20

• Measured in Hertz
• MHz- million instructions per second.
• GHz - billion instructions per second.
• so 3.4GHz = 3.4 billion FDE cycles per second

Question 21

Overclocking

Answer 21

using a clock speed higher than the computer was designed for:

• Operations become unsynchronised (computer would crash often)
• Lead to serious overheating of the CPU

Question 22

Increasing clock speed:

Answer 22

• Improves performance
• more FDE cycles can be processed in a second

Question 23

How to improve data bus performance

Answer 23

Lengthen data bus wire

Question 24

Embedded systems

Answer 24

combination of hardware and software which is designed to carry out a specific set of tasks

Question 25

Embedded system characteristics

Answer 25

• Performs a single task
• It has a microprocessor
• It has dedicated hardware
• works without human intervention
• Non-programmable devices

Question 26

Purpose and process of embedded systems

Answer 26

Purpose: to control the device and allow a user to interact with it

Process:
- Input from the user is sent to the microprocessor
- Microprocessor then sends signals to actuators to perform task (output)

Question 27

Advantages of embedded systems:

Answer 27

• Small in Size, can easily fit into devices
• Low cost to make
• Very fast reaction to changing input

Question 28

Disadvantages of embedded systems:

Answer 28

• Difficult to upgrade
• The interface can be confusing
• Troubleshooting is a specialist’s job

Question 29

Process of FETCH

Answer 29

– Program counter (PC) holds address of the instruction
– The address held in PC is sent to MAR
– using address bus
– PC is incremented by one
– The instruction is fetched and sent from main memory to MDR
– using the data bus
– Instruction sent from MDR to CIR

Question 30

DECODE

Answer 30

The instruction in the CIR is decoded, by the Control unit, into an opcode and an operand

Question 31

EXECUTE

Answer 31

• The instruction is executed by the ALU and the opcode is performed upon the operand.
• The result is stored in the accumulator or written to a memory location within memory