1.2 Memory and Storage Flashcards

1
Q

Primary Storage

A

Memory that the CPU can access very quickly

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2
Q

Need for primary storage

A

For data it needs to access quickly

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3
Q

Examples of things stored in primary storage

A

Operating System
BIOS
Boot up instructions

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4
Q

Types of primary storage

A

ROM
RAM

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5
Q

Purpose of ROM in a computer system

A

Non - volatile
Contains BIOS for the boot process

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6
Q

Purpose of RAM in a computer system

A

Volatile
Operating system is copied into RAM from secondary storage when computer boots up
CPU can access quickly - stores data, files, and programs that are being used

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7
Q

ROM full form

A

Read-only memory

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8
Q

RAM full form

A

Random access memory

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9
Q

Volatile memory

A

Temporary
Needs power to retain data

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10
Q

Non - volatile memory

A

Permanent
Retains. data when there is no power

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11
Q

BIOS

A

Basic Input Output System
Instructions a computer needs to properly boot up

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12
Q

Virtual Memory

A

When RAM gets full, the computer moves less recently used data into a section of secondary storage (virtual memory)

For the CPU to read data in virtual memory, it needs to be swapped back into RAM

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13
Q

When is virtual memory needed?

A

When too many applications are running at once

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14
Q

Disadvantage of Virtual Memory

A

Makes a computer slow to respond when switching between applications (swapping them in and out of RAM)

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15
Q

Secondary Storage

A

Where data is stored when not in use

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16
Q

Need for secondary storage

A

To store files and programs

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17
Q

Common types of secondary storage

A

Optical
Magnetic
SSD
HDD

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18
Q

Hard Disk Drives (HDDs)

A

Stack of magnetised metal disks that spin
Have a read-write head which can read + write data

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19
Q

Solid State Drives (SSDs)

A

No moving parts = silent
Use a type of flash memory
Higher read-write speed than HDDs

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20
Q

Advantages of HDDs

A

Cheap
High capacity
Longer read-write life than SSDs

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21
Q

Advantages of SSDs

A

Faster
Don’t need to be defragmented (slows them down!)
Shock - proof
Silent

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22
Q

Optical Storage

A

Uses light to store data

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23
Q

Examples of optical discs

A

CD
DVD
Blu-ray

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24
Q

Types of Optical Discs

A

Read only (e.g. CD-ROM)
Write once (e.g. CD-R)
Rewritable (e.g. CD-RW)

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25
Q

Why use of optical discs is declining

A

Streaming services have become popular e.g. Netflix
Modern devices e.g. phones don’t have optical drives

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26
Q

Disadvantages of Optical Storage

A

Low capacity
Slow read/write speed
Poor reliability
Scratches

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27
Q

Advantages of Optical Storage

A

Cheap
Portable
Not affected by water or shock

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28
Q

Advantages of Magnetic Tapes

A

Large capacity
Cheap
Fast rad/write speed

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29
Q

Where are magnetic tapes used?

A

In archives of large organisations

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30
Q

Disadvantages of Magnetic Tape

A

Read/write sequentially -> difficult to find a specific piece of data on it

31
Q

Bit

A

Single binary digit (1 or 0)

32
Q

Nibble

A

4 bits

33
Q

Byte (B)

A

8 bits

34
Q

Kilobyte (KB)

A

1000 Bytes

35
Q

Megabyte (MB)

A

1000 Kilobytes

36
Q

Gigabyte (GB)

A

1000 Megabytes

37
Q

Terabyte (TB)

A

1000 GIgabytes

38
Q

Petabyte (PB)

A

1000 Terabytes

39
Q

Why does data need to be converted to binary so that the computer can read it?

A

Computers only process binary digits
Binary digits represent the flow of electricty

40
Q

How do computers process alphanumerical character?

A

Character sets

41
Q

Character Set

A

A collection of characters that a computer recognises due to their binary representation

More number of bits per character = more characters

42
Q

What happens when you press a key on your keyboard?

A

Sends a binary signal to the computer telling it which key was pressed
The computer uses the character set to translate it into binary

43
Q

Examples of Character Sets

A

ASCII
Unicode

44
Q

ASCII

A

7-bit binary code -> 128 characters

45
Q

Unicode

A

Covers all major symbols and languages
Uses multiple bytes
First 128 codes are the same as ASCII

46
Q

How are images stored?

A

Made up of pixels

47
Q

Types of images

A

Bitmap
Vector

48
Q

What is the colour of each pixel represented by?

A

Binary

49
Q

Colour Depth

A

The number of bits used for each pixel

50
Q

How to work out the total number of colours

A

2*n(number of bits per pixel)

51
Q

Image Resolution

A

Number of pixels in the image

52
Q

How to work out image resolution

A

Width x Height

53
Q

How does colour depth and resolution effect the quality of the image?

A

Higher resolution and higher colour depth = better quality of image

54
Q

How to work out file size

A

Image resolution x colour depth
Width x height x colour depth

55
Q

Metadata

A

Data about data
Information stored in an image which helps the computer recreate the image on screen

56
Q

Examples of things stored in metadata

A

File format
Height
Width
Colour Depth
Resolution

57
Q

Sampling

A

The process of converting from analogue to digital

58
Q

How can analogue sound be converted into digital data?

A

Analogue to digital converters

59
Q

Sample Rate

A

How many samples are taken in a second
In Hz

60
Q

Bit depth

A

Number of bits available for each sample

61
Q

How to calculate file size

A

Sample Rate x Bit Depth x Length

62
Q

How does sample rate + bit depth effect the playback quality

A

Higher sample rate = better quality
Higher bit depth -> the digital file also picks quieter sounds = better quality

63
Q

How does sample rate + bit depth effect file size

A

Higher bit depth + sample rate = higher file size

64
Q

Data Compression

A

To make file sizes smaller

65
Q

Uses of Data Compression

A

Takes up less storage
Streaming + downloading files from the Internet is quicker as less bandwidth is used
Web pages download quicker
Email services have restrictions on file size

66
Q

Types of Compression

A

Lossy
Lossless

67
Q

Lossy Compression

A

Permanently removes data from the file

68
Q

Lossless Compression

A

Temporarily removes data from the file to store it, and restores it when it is opened

69
Q

Advantages of Lossy

A

High file size reduction
Use up less bandwidth -> can be streamed and downloaded quickly
Commonly used

70
Q

Disadvantages of Lossy

A

Loses data -> file cannot be reverted back to the original
Cannot be used on text files
Highly reduce quality of image

71
Q

Examples of Lossy file types

A

MP3
AAC
JPEG

72
Q

Advantages of Lossless Compression

A

Data is only removed temporariliy -> when opened there is no reduction in quality
Can be used for text files

73
Q

Disadvantages of Lossless Compression

A

Only slight reduction in file size

74
Q

Examples of Lossless file types

A

FLAC
TIFF
PNG