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Computer Science > 1.2 - Memory & Storage > Flashcards

1.2 - Memory & Storage Flashcards

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1
Q

What is RAM?

A

High speed, volatile memory

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2
Q

What is the Operating system?

A

The software that manages the hardware and software resources in a computer system

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3
Q

What does OS stand for?

A

Operating system

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4
Q

Give an example of some programs that is stored in the RAM:

A
  • Programs that is currently in use
  • Open documents
  • OS
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5
Q

What does RAM stand for?

A

Random access memory

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6
Q

What is ROM?

A
  • Non-volatile, memory
  • Stores instructions & data that are needed for the computer to run
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7
Q

Give an example of a program that is stored in the ROM:

A

BIOS

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8
Q

What is the purpose of the BIOS?

A
  • Checks if hardware is functioning correctly
  • Then, runs bootstrap program that loads the computer’s OS from the hard drive into the RAM
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9
Q

What does ROM stand for?

A

Read only memory

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10
Q

Where is the ROM located in the computer?

A

Built into the motherboard

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11
Q

What is Volatile memory?

A
  • Temporary memory
  • Requires power to retain data
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12
Q

What is Non-volatile memory?

A
  • Permanent memory
    —> Keeps its contents even when it has no data
  • Primary memory
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13
Q

What is Primary storage?

A

Holds data, programs and instructions that are currently in use

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14
Q

What does primary storage include?

A
  • RAM
  • ROM
  • Cache
  • Flash memory
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15
Q

What is Primary storage also known as?

A

Main memory

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16
Q

What is Virtual memory?

A

A section of a computer storage drive (HDD) which is temporarily used as RAM

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17
Q

When is Virtual memory needed?

A

When you need to run applications on the computer than its physical memory (RAM) can support
—> It lets more memory to be used than there is in the system.

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18
Q

What is Swapping?

A

The process of moving data between RAM and secondary storage when using virtual memory

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19
Q

What are the disadvantages of using Virtual memory?

A
  • Makes a computer slow to respond when switching applications
  • Excessive use can cause disk thrashing
    —> which decreases performance
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20
Q

Why is Virtual memory slower to respond when switching applications?

A

In the VM, the data would still need to be moved to RAM before it could be accessed
—> This is what slows down the access speed

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21
Q

How can the processing performance be improved of a computer that frequently uses virtual memory?

A

INCREASING the size of the RAM
—> reduces the need for virtual memory

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22
Q

What is secondary storage?

A

Non-volatile memory external to the CPU and used for long-term storage of programs and data

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23
Q

Name some common types of secondary storage:

A
  • Optical
  • Magnetic
  • Solid State
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24
Q

Name some examples of Optical storage devices:

A
  • CD
  • DVD
  • Blu-ray discs
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25
Q

Name some examples of Magnetic storage devices:

A
  • Hard disk drives
  • Magnetic tape
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26
Q

Name some examples of Solid state storage devices:

A
  • Solid state drives
  • USB memory sticks
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27
Q

What does HDD stand for

A

Hard disk drive

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28
Q

Describe the structure of HDD:

A

Made up of a stack of magnetised metal disks
—> Spins 1000 times / sec

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29
Q

How is data stored in a HDD?

A

Magnetically
—> In small areas on the disks circular tracks

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30
Q

What is Flash memory?

A

Non-volatile memory that can be read from and written to
—> It is suitable for secondary storage

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31
Q

What are the advantages of HDDs?

A
  • Cheap
  • High capacity
  • Fast read/write speed
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32
Q

What are the disadvantages of HDDs?

A
  • Not portable
  • Not durable - due to moving parts
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33
Q

What are the advantages of SSD?

A
  • Durable
  • Portable
  • Fast
  • Don’t need defragmenting
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34
Q

What are the disadvantages of SSD?

A
  • Expensive
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35
Q

What are the disadvantages of Flash storage?

A
  • Small capacity
  • Slower than SSDs
  • Shorter read/write life
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36
Q

What are the advantages of Optical discs?

A
  • Cheap
  • Very easily portable
  • Takes up little space physically
  • Won’t be damaged by water or shocks
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37
Q

What are the disadvantages of Optical discs?

A
  • Less storage capacity compared to other types
  • Easily scratched
  • Requires a CD reader
  • Slow write speeds
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38
Q

Where are Magnetic tapes often used?

A
  • Personal computers
  • Large organisations
  • To sore HUGE amounts of data
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39
Q

What are the uses of Optical storage?

A
  • Songs, videos and other multi-media storage
  • Backup and archiving of data
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40
Q

What are the uses of Optical storage?

A
  • Higher end computers
  • Laptops
  • Smartphones and tablets
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41
Q

Name some characteristics

A
  • Capacity
  • Speed
  • Portability
  • Durability
  • Reliability
  • Cost
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42
Q

What are Bits?

A

The smallest measurement of data

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43
Q

What are the units in computing, from smallest to largest?

A
  • Bit
  • Nibble
  • Byte
  • Kilobyte
  • Megabyte
  • Gigabyte
  • Terabyte
  • Petabyte
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44
Q

How do computers represent the Flow of electricity?

A

By using 1s and 0s

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45
Q

What number system do we use?

A

Decimal number system

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46
Q

How many digits does the decimal number system have?

A

10 digits (base 10)

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47
Q

What base is binary?

A

2

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48
Q

How do you convert from denary to binary?

A
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49
Q

How do you convert from binary to denary?

A
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50
Q

Binary addition

0 + 0 = ?

A

0

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51
Q

Binary addition

1 + 0 = ?

A

1

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52
Q

Binary addition

1 + 1 = ?

A

0 carry 1

53
Q

Binary addition

1 + 1 + 1 = ?

A

1 carry 1

54
Q

When does an overflow error occur?

A

When the result of a calculation requires more bits (place values) than are in the available range

55
Q

How do you convert hex to denary?

A
56
Q

How do you convert denary to hex?

A

Or divide the denary number by 16. Convert that first number into hex (if needed). Take the remainder and convert it into hex (if needed)

57
Q

What base is hexadecimal?

A

16

58
Q

Why might programmers use hex instead of binary?

A

Hex is easier to understand than binary.

Programmers often use hex to represent binary values as they are simpler to write and check than when using binary.

59
Q

How are binary numbers multiplied and divided?

A

By shifting

60
Q

How do you multiply a binary number?

A

Move the binary digits along to the left

61
Q

How do you multiply a binary number by 2?

A

All digits shift one place to the left

62
Q

How do you multiply a binary number by 4?

A

All digits shift two places to the left

63
Q

How do you multiply a binary number by 8?

A

All digits shift three places to the left

64
Q

How do you divide a binary number?

A

Move the binary digits along to the right

65
Q

How do you divide a binary number by 2?

A

All digits shift one place to the right

66
Q

How do you divide a binary number by 4?

A

All digits shift two places to the right

67
Q

How do you divide a binary number by 8?

A

All digits shift three places to the right

68
Q

What is a character set?

A

A table of data that links a character to a number. This allows the computer system to convert text into binary.

69
Q

Give some examples of some character sets

A
  • ASCII
  • Unicode
  • Extended ASCII
70
Q

What is ASCII?

A

A 7-bit character set used for representing English keyboard characters.

71
Q

How many characters does ASCII have?

A

128

72
Q

What does ASCII stand for?

A

American Standard Code for Information Interchange

73
Q

What is Extended ASCII?

A

Extended ASCII uses eight bits.

—> Allows for special characters such as those with accents in languages such as French and Spanish

74
Q

How many characters does Extended ASCII have?

A

256

75
Q

What is Unicode?

A

Unicode uses 16 bits, giving a range of over 65,000 characters. Represents languages such as Arabic or Chinese

76
Q

How many characters does Unicode have?

A

Over 65,000

77
Q

How do you calculate the file size of a text file?

A

number of bits per character x number of characters

78
Q

What are the types of images?

A
  • Bitmap
  • Vector
79
Q

What is a pixel?

A

Picture element - a single dot of colour in a digital bitmap image or on a computer screen

80
Q

What are bitmap images made of?

A

Pixels arranged on a grid

81
Q

How do pixels show colour?

A

Each pixel is assigned a binary value which represents the colour of that pixel

82
Q

What does the quality of a bitmap image depend on?

A

Image resolution (total amount of pixels)

83
Q

What is the result of scaling up a bitmap image?

A

It will result in visible loss of quality

84
Q

Give some examples of bitmap images

A

Most images on computers (e.g. photos and screenshots)

85
Q

What are vector images?

A

Drawn by the computer following precise mathematical instructions to create lines and objects

86
Q

What is the file size of vector images compared to bitmaps?

A

Vector files are smaller compared to bitmaps

87
Q

Why are vector files smaller than bitmap images?

A

As each pixel in a bitmap is stored as an individual binary value

88
Q

What is the result of scaling up a vector image?

A

Scaled up without any loss of quality

89
Q

What are vector images typically used for?

A

Logos and animations

90
Q

What is colour depth?

A

The amount of bits available for colours in an image

91
Q

What is image size?

A

The number of pixels that an image contains. It is expressed as height and width

e.g. 1024 x 764

92
Q

What is the resolution of an image?

A

The concentration of pixels within a certain area

93
Q

How can you make a greater range of shades & colours?

A

By increasing the number of bits for each pixel

94
Q

How do you work out number of possible colours?

A

Total num of colours = 2^n

n = numb of bits per pixel

95
Q

How many colours does one bit represent?

A

2 colours

96
Q

How many colours does two bits represent?

A

4 colours

97
Q

How many colours does three bits represent?

A

8 colours

98
Q

How many colours does eight bits represent?

A

256 colours

99
Q

How many colours does the RGB model use?

A

3 bytes altogether:
1 byte of 256 colours each

100
Q

How do you calculate the file size of an image file?

A

Image resolution x colour depth

101
Q

What is metadata?

A

Additional data about a file

102
Q

Give some examples of metadata

A
  • Author details
  • Colour depth
  • Geolocation
  • Date created
103
Q

How do you convert analogue sound to digital (binary)?

A

Using an ADC. The amplitude of the analogue sound wave is measured and recorded in binary at specific intervals

104
Q

What is a sample?

A

A digitally recorded fragment of sound, taken from an existing track or sound environment

105
Q

What is Sample rate?

A

The number of times (per sec) the amplitude of the sound wave is measured

106
Q

What is sample rate measured in?

A

Kilohertz (kHz)

107
Q

Why will increasing the sample rate improve audio quality?

A

The digital data more closely resembles an analogue wave

108
Q

What will higher sample rates result in?

A

Larger files

109
Q

Why will higher sample rates result in larger file sizes?

A

As much more data is stored for each individual sample

110
Q

How do you improve the quality of an audio?

A
  • Increasing sample rate
  • Increasing bit depth
111
Q

What is bit depth?

A

Number of bits available to represent each sample

112
Q

Why will increasing the bit depth improve audio quality?

A

The more bits available to be used for each sample.
—> Therefore quality is higher as the wave resembles more closely to an analogue wave

113
Q

What will a higher bit depth result in?

A

Larger file size

114
Q

Why will a higher bit depth result in larger file sizes?

A

As each sample stores additional bits

115
Q

How do you calculate the file size of a sound file?

A

Sound file size = Sample rate (in Hz) x duration (s)

116
Q

What is compression?

A

A method of reducing file sizes, particularly in digital media such as photos, audio and video

117
Q

What are the benefits of compression?

A
  • Files take up less storage space
  • Files can be transferred quicker
  • Files can be read from or written to quicker
118
Q

What are the methods to compress a file?

A
  • Lossy
  • Lossless
119
Q

How does lossy compression work?

A

Uses an algorithm that analyses and permanently removes data from the file which cannot be seen or heard by humans
—> This reduces file size
—> File can’t return to its original form

120
Q

What type of files would you often use lossy compression on?

A
  • Images
  • Audio
  • Videos
121
Q

What are some advantages of lossy compression?

A
  • Greatly reduced file size
  • Lossy files take up less bandwidth
  • Commonly used
122
Q

How does lossy compression positively impact bandwidth?

A

Can be downloaded more quickly

123
Q

What are some disadvantages of lossy compression?

A
  • Loses data that can’t be brought back
  • Can’t be used on text or software files
  • Worse quality than the original (but loss in quality is usually unnoticeable)
124
Q

Give some examples of some file types that use lossy compression

A
  • MP3
  • JPEC
  • AAC
125
Q

How does lossless compression work?

A

Makes the file smaller by temporarily removing data to store the file. It returns to its original state when opened

126
Q

What type of files would you often use lossless compression on?

A
  • Word documents
  • Programs
  • Games
127
Q

What are some advantages of lossless compression?

A
  • No reduction in quality - data is temporarily removed
  • Can be decompressed (turned back into the original)
  • Can be used on text and software files
128
Q

What are some disadvantages of lossless compression?

A

Only a SLIGHT reduction in file size - so it can still take up quite a bit of space

129
Q

Give some examples of some file types that use lossless compression

A
  • WAV
  • PNG
  • TIFF

Computer Science (13 decks)

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