Chapter 1: How do Computers Work?

Question 1

Computer

Answer 1

Device that receive, process data according to a set of instructions and produce the processed data as a result

Question 2

Computer architecture

Answer 2

How the computer is designed and built to function, how parts of computer are designed, organised and connected

Question 3

Data

Answer 3

Information used in a computer program

Question 4

Bit

Answer 4

Binary digit which can take on the value of either 0 or 1

Question 5

Byte

Answer 5

Binary number made up of eight bits

Question 6

Size of different types of bytes

Answer 6

Name of unit	Size in bytes
kilobyte (kB)	1000
kibibyte (KiB)	1024
megabyte (MB)	1000^2 = 1 000 000
mebibyte (MiB)	1024^2 = 1 048 576
gigabyte (GB)	1000^3 = 1 000 000 000 
gibibyte (GiB)	1024^3 = 1 073 741 824
terabyte (TB)	1000^4 = 1 000 000 000 000
tebibyte (TiB) 	1024^4 = 1 099 511 627 776

Question 7

Central processing unit (CPU)

Answer 7

Part of the computer that processes data and follows instructions

Question 8

Arithmetic logic unit (ALU)

Answer 8

Part of the processor that processes data by performing basic mathematical and logical operations

Question 9

Control unit

Answer 9

Part of the processor that follows instructions and decides where the data should be stored, received and transmitted by different parts of the computer.

Question 10

Execute

Answer 10

To follow or perform an instruction

E.g. processor executes an instruction

Question 11

Software

Answer 11

Set of instructions to perform specific tasks on a computer

Question 12

Address

Answer 12

Number that is used to locate a byte in memory

Question 13

Memory

Answer 13

Device that is used to store data for immediate use in a computer

Question 14

Processor registers (PR)

Answer 14

Part of the processor; they are fast but small data storage spaces that are used directly by the ALU and control unit.
Number and size of PRs cannot be changed without changing the processor

Question 15

Random access memory (RAM)

Answer 15

Where data and instructions are stored temporarily so that they can be quickly accessed by the processor when needed
E.g. When an application is started, its instruction may be loaded into RAM
RAM can be easily changed and is also volatile, which means that it is lost once the power supply to the computer is interrupted.

Question 16

Read-only memory (ROM)

Answer 16

Where data and instructions that rarely need to change or would be needed for a computer to start up are stored.
Data on it can’t be easily changed and remains there whether power supply is switched on or off
Ideal for storing instructions that are needed before data can be loaded into the RAM

Question 17

Hard disk (or hard drive)

Answer 17

Secondary storage where data is stored on rigid rotating disks coated with magnetic material

Question 18

Bus

Answer 18

Collection of wires for transporting data from one part of a computer to another

Question 19

Bi-directional

Answer 19

Able to work in two directions; to and fro

Question 20

Data bus

Answer 20

Bus that is used to transport data that is going to be processed by the CPU, as well as data that has already been processed by the CPU, hence it is bi-directional as data is transported between memory and processor

Question 21

Address bus

Answer 21

Used to specify address information

Uni-directional because address information is sent from processor to memory

Question 22

Input

Answer 22

Data or instructions that the computer receives for processing

Question 23

Output

Answer 23

Intermediate or final results produced by computer in the form of processed data

Question 24

Hardware

Answer 24

Physical part of a computer

Question 25

Input Device

Answer 25

Hardware device that allows users to enter data and instructions into a computer

Question 26

Output Device

Answer 26

Hardware device used to display, project or print processed data from a computer

Question 27

External storage

Answer 27

Removal device to store large amounts of data

Question 28

Factors affecting storage

Answer 28

• Capacity
• Speed
• Portability
• Durability
• Cost

Question 29

Magnetic external storage

Answer 29

Data is stored on a magnetic material that can be read or written by a magnetic “head”
- Advantages:
- Large storage capacity of up to terabytes of data
- Relatively cheaper compared to optical and solid-
state
- Disadvantages:
- Vulnerable to drops and mechanical shocks

Question 30

Optical external storage

Answer 30

Data is stored as very small pits or indentations that be read or written by a laser
- Advantage:
- Large storage capacity of up to gigabytes of data
- Disadvantages:
- Data can only be written once for some non-
rewritable formats
- Lower maximum storage capacity then magnetic
- Vulnerable to scratches and fingerprints

Question 31

Solid-State external storage

Answer 31

Data is stored in electronic circuits called “flash memory” that have no moving parts
- Advantage:
- Much faster compared to optical or magnetic
- Not as vulnerable to drops, mechanical shocks,
scratches or fingerprints
- Smaller in size and lighter in weight than
magnetic or optical
- Uses very little power and produces no noise
- Disadvantage:
- Much more expensive compared to optical or
magnetic

Question 32

Data flow

Answer 32

Path taken by a set of data `

Question 33

Operating system

Answer 33

Software designed to support a computer’s basic functions

Question 34

Application

Answer 34

Software designed for users to perform specific tasks