1.2 Memory and Storage

Question 1

The need for Primary Storage

Answer 1

When the computer is on, the operating system and any utilities and data required to run the computer are stored in primary memory.
When a program is loaded to a computer it, and any data it uses, are also stored in primary memory.

Question 2

The Difference between RAM and ROM

Answer 2

ROM is non-volatile whereas RAM is volatile
Content of ROM cannot usually be changed whereas the content of RAM can be changed

Question 3

Purpose of ROM in a Computer System

Answer 3

• Provides storage for data and instructions for starting up and initialising the computer
• It is Read-Only memory because the computer cannot overwrite its content
• Information stored on ROM is usually programmed by the manufacturer

Question 4

Purpose of RAM in a Computer System

Answer 4

• RAM is the main memory in a computer
• RAM holds the operating system, applications, and data currently in use by the computer
• The CPU can access RAM very quickly and access times are much faster than those for secondary storage e.g. hard disk
• The more RAM in a computer, the more programs, and data it can keep available
• Data is transferred from secondary storage, to RAM, to Cache, to the CPU

Question 5

Virtual Memory

Answer 5

Part of the hard disk used as a temporary store for some of the data in main memory

Question 6

Flash Memory

Answer 6

Solid-state memory and is used in portable or removable devices to store data
It is faster than a magnetic hard disk but slower than RAM

Question 7

The Need for Secondary Storage

Answer 7

To store data once the computer is turned off/non-volatile storage

Question 8

Optical Storage

Answer 8

• Ideal for distributing data
• Low cost
• Robust
• Ideal for archive storage

Question 9

Magnetic Storage

Answer 9

• Large storage capacity
• Cost to purchase is low
• Compact in size
• Reliable method of storage

Question 10

Solid State Storage

Answer 10

• Large storage capacity
• Durable/Robust
• Fast data access
• Cost to purchase is low
• Runs quietly
• Produces little heat
• Uses little energy
• Compact/Lightweight

Question 11

Bit

Answer 11

Smallest unit of data measurement
0 or 1

Question 12

Nibble

Answer 12

4 bits
Can represent 16 unique values

Question 13

Byte

Answer 13

8 bits

Question 14

Kilobyte

Answer 14

1024 bytes

Question 15

Megabyte

Answer 15

1024 kilobytes

Question 16

Gigabyte

Answer 16

1024 megabytes

Question 17

Terabyte

Answer 17

1024 gigabytes

Question 18

Petabyte

Answer 18

1024 terabytes

Question 19

Character Sets

Answer 19

All the different characters a computer can represent

Question 20

ASCII

Answer 20

An 8 bit character set.
Can represent a maximum of 256 different characters - not enough for all the international languages

Question 21

Unicode

Answer 21

Uses 16 bits per character so it can represent all the characters in most international languages

Question 22

Representing Images as a Series of Pixels

Answer 22

Each colour has a unique binary code
A bitmap is made of pixels

Question 23

Metadata

Answer 23

Can store file information on image height, width, colour, date, Geolocation, File size, File type, Compression Type and Creator

Question 24

The Effect of Colour Depth and Resolution on the Quality of an Image

Answer 24

The number of bits used to store each pixel in an image dictates how many colours an image can contain.
The number of bits per pixel is referred to as the colour depth
If the colour depth is increased, more bits are used to represent each pixel and the overall size of the image will increase.

Question 25

The Effect of Colour Depth and Resolution on the Size of an Image File

Answer 25

The higher the colour depth (number of colours), the higher the quality of the image which will increase the number of pixels needed to represent the image. The greater the number of pixels, the sharper the image will be and the larger the file size of the image will be.

Question 26

How Sound can be Sampled and Stored in Digital Form

Answer 26

Analogue sound wave is sampled Amplitude is measured at regular intervals Each sample is stored as a binary number The binary number for each sample is stored sequentially

Question 27

Sample Rate

Answer 27

The sample rate is the number of times the amplitude is recorded per second

Question 28

The Effect of Sample Rate, Duration and Bit Depth on Playback Quality

Answer 28

The smaller the bit depth the smaller the range of sounds recorded

Question 29

The Effect of Sample Rate, Duration and Bit Depth on the Size of a Sound File

Answer 29

The sample rate is the frequency with which you record the amplitude of sound, usually measured in Hertz. The more frequently the sound is sampled, the better the quality of the playback.

Question 30

The Need for Compression

Answer 30

Reduces file size Ensures files take up less space on a server Faster upload speeds to a server Faster download speeds for users Uses less bandwidth to transmit data

Question 31

Lossy Compression

Answer 31

Will reduce the file size by a large amount Will remove data that is not noticeable/the changes will allow for further reduction without the user noticing Text files cannot be compressed with lossy Data is permanently lost with lossy compression

Question 32

Lossless Compression

Answer 32

Files are compressed by not data is lost Essential for text and data files Used to compress files WinZip is a common utility software that uses lossless compression