Topic 5-Computer Hardware

Question 1

Central processing unit (CPU)

Answer 1

• The CPU (central processing unit) is often referred to as the ‘brain’ of the computer
• Its main role is to process programs and data
• It does this by repeatedly fetching an instruction from memory and executing it (fetch-execute cycle)

Question 2

Component-Control unit

Answer 2

• Decides which instruction to carry out next
• Fetches it from memory
• Decodes the instruction and executes (or obeys) the instruction
• Repeats the process (fetch-execute cycle)

Question 3

Component-Arithmetic and logic unit(ALU)

Answer 3

• Carries out arithmetic calculations,e.g addition,multiplication,subtraction,division
• Preforms logical comparisons to assist with decision-making by using the operators AND,OR and NOT

Question 4

Component-Immediate access store (IAS)

Answer 4

• Stores all programs and data temporarily while they are in use
• During the fetch-execute cycle,instructions are fetched from their specific storage location in the IAS using an address

Question 5

Fetch-execute cycle

Answer 5

• The CPU includes a number of registers
• These are high-speed memory locations,each used for specific purposes
• The registers below have an important role during the fetch-execute cycle

Question 6

Registers-Program Counter (PC)

Answer 6

• A PC stores the address (memory location reference) of the next instruction to be fetched.
• It is automatically incremented by 1 every time wn instruction is fetched

Question 7

Register-Memory Address register (MAR)

Answer 7

The address of the current instruction or data being executed is temporarily stored in the MAR

Question 8

Register-Memory data register (MDR)

Answer 8

This register will temporarily store data being fetched from or written to the main memory of the CPU

Question 9

Register-Instruction Register (IR)

Answer 9

This register temporarily stores the current instructions to be decoded and then executed

Question 10

Accumulator

Answer 10

When calculations take place on data,the results are initially stored in the accumulator before being transferred and stored in the main memory

Question 11

Factors that influence the speed of processing-Clock speed

Answer 11

• The clock speed measures the number of instruction cycles the CPU can deal with in a second
• The standard unit of measurement for clock but speed is gigahertz (Ghz)

Question 12

Factors that influence the speed of processing-Cache

Answer 12

• Cache temporarily frequently used instructions and data

- It is quicker to search cache memory than RAM,thus increasing processor speed

Question 13

Factors that influence the speed of processing-Processor Core

Answer 13

• A core can be defined as a single processor
• More advanced CPUs contain more than one core,which will increase their ability to run many programs at the same time,for example,a ‘quad core’ processor has four processors

Question 14

The purpose of a microphone

Answer 14

• Accepts sound input or human voice into a computer system

- A voice recognition system can convert sound to text

Question 15

Advantages of a microphone

Answer 15

• Faster to speak using a microphone than typing words using a keyboard
• It is hands free,allowing users to carry out other activities at the same time as voice input

Question 16

Disadvantages of a microphone

Answer 16

• The recognition rate of spoken words can be low if there is background noise
• Sound files require greater storage capacity than text files

Question 17

Purpose of a mouse

Answer 17

• Used to control the pointer/cursor on a VDU
• Uses built in sensors to detect movements and send corresponding signals back to the computer
• Also includes buttons used to make selections on the screen

Question 18

Advantages of a mouse

Answer 18

• Easy to use and requires little or no training

- Quicker to select menus and icons compared to using a keyboard

Question 19

Disadvantages of using a mouse

Answer 19

• Experienced users find it slow compared to using ‘hot keys’
• Need a flat service (additional space) to function properly

Question 20

Purpose of a graphics designer

Answer 20

• Allows a user to hand-draw images,which are captured by the computer
• Consists of a flat electronic sensitive surface and a stylus pen

Question 21

Advantages of using a graphics designer

Answer 21

• More natural to draw diagrams with a stylus than with a mouse
• Using a stylus produces more accurate and detailed drawings

Question 22

Disadvantages of using a graphics designer

Answer 22

• Not suitable for selecting menus snd pointing at menu items
• More expensive than a mouse

Question 23

Purpose of a touchscreen

Answer 23

• Looks similar to ordinary computer screens,with a touch-sensitive surface/membrane
• When the screen is touched the position is calculated as a (x,y) co-ordinate

Question 24

Advantages of a touchscreen

Answer 24

• User does not require much ICT competence compared to using a keyboard
• Users can select and enter options much faster than using a keyboard

Question 25

Disadvantages of a touchscreen

Answer 25

• Limited number of options available on screen

- Screens can become dirty quickly

Question 26

Purpose of a speaker

Answer 26

• Allows sound to be outputted
• May be internal or external speaker
• In addition to the hardware,a sound card needs to be fitted inside the computer

Question 27

Advantages of a speaker

Answer 27

• Useful for visually impaired users:text or figures can be spoken by the computer
• Natural way to communicate with users

Question 28

Disadvantages of using a speaker

Answer 28

• External speakers require additional desk space connected to using headphones
• Speakers can distract other users in the same office who are doing other tasks

Question 29

Purpose of a laser printer

Answer 29

• A laser beam is used to scan the image of the page to be printed onto a drum by building a pattern of static electricity
• This attracts toners (printer ink) to reproduce the page