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CC-2224 Computer Science Paper 1 > Memory And Storage > Flashcards

Memory And Storage Flashcards

1
Q

Computer systems need …

A

both primary and secondary storage to operate

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2
Q

What are the properties of primary storage

A

-Volatile (with the exception of ROM)
-Small capacity

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3
Q

What are the properties of secondary storage

A

-Non-volatile
-Large capacity

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4
Q

Why do you need primary storage

A

A computer needs primary storage because access times are considerably faster than secondary

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5
Q

What is RAM

A

RAM (Random Access Memory) is primary storage that is directly connected to the CPU and holds the data and instructions that are currently in use

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6
Q

RAM is …

A

volatile

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7
Q

What are the properties of RAM

A

-very fast working memory, much faster than secondary storage
-RAM is read/write which means data can be read from and written to
-It has a much larger capacity than ROM

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8
Q

What is ROM

A

ROM (Read Only Memory) is primary storage that holds the first instructions a computer needs to start up (Bootstrap)

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9
Q

ROM contains the …

A

BIOS (Basic Input Output System)

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10
Q

ROM is …

A

non-volatile

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11
Q

What are the properties of ROM

A

-It is faster than secondary storage but slower than RAM
-ROM is read only which means data can only be read from
- it has a much smaller capacity than RAM

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12
Q

What is virtual memory

A

Virtual memory is an extension of primary storage (RAM) located on secondary storage

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13
Q

Why is virtual memory used

A

where RAM is close to being full, virtual memory can be used so that the computer remains operational

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14
Q

What are the properties of virtual memory

A

It is much slower than RAM and it’s use will impact negatively on system performance

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15
Q

Why do you need secondary storage

A

A computer needs secondary storage for long term storage of programs and data that are currently not in use

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16
Q

Secondary storage holds …

A

the programs and data whilst the computer is turned off

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17
Q

Performance of secondary storage is

A

slower than primary storage

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18
Q

What are the characteristics of secondary storage

A

-Capacity
-Speed
-Cost
-Portability
-Durability
-Reliability

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19
Q

What are the 3 types of secondary storage

A

-Magnetic
-Solid State
-Optical

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20
Q

What is magnetic storage

A

Magnetic storage is a type of non-volatile media that uses magnets to store binary 0s and 1s

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21
Q

What are the advantages of magnetic storage

A

-Capacity - High storage
-Cost - Low per gigabyte
-Speed - Moderate read/write access

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22
Q

What are the disadvantages of magnetic storage

A

-Durability - Moving parts can get damaged if dropped
-Portability - Heavy & bulky making them less convenient for transport
-Reliability - Prone to mechanical failure
-Noise - Loud (spinning disks)

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23
Q

What is solid state storage

A

Solid state storage is a type of non-volatile media that uses electronic circuits to store binary 0s and 1s

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24
Q

What are the advantages of solid state storage

A

Capacity - Medium/high storage
Speed - Very fast read/write access Reliability - Limited read/write cycles
Durability - No moving parts
Portability - Small and no moving parts
Noise - Silent

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25
Q

What are the disadvantages of solid state storage

A

-Cost - Very high per gigabyte
-Reliability - Limited read/write cycles

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26
Q

What is optical storage

A

Optical storage is a type of non-volatile media that uses lasers to burn the surface of a disk, creating pits and lands suitable for storing binary 0s and 1s

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27
Q

What are the advantages of optical storage

A

Cost - Very low per gigabyte
Durability - No moving parts
Portability - Small
Noise - Silent

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28
Q

What are the disadvantages of optical storage

A

-Capacity - Very low
-Speed - Very slow read/write access
-Reliability - Prone to scratches

29
Q

Computers use binary numbers to …

A

represent data

30
Q

What are units of data

A
31
Q

Why does data have to be converted to binary to be processed by a computer

A

A computer is built using switches that can either be on or off ( 1= on, 0= off)

32
Q

What is the formula to calculate the text file size

A

Bytes per character x Number of characters

33
Q

What is the formula to calculate the image file size

A

Resolution x Colour Depth

34
Q

What is the formula for resolution

A

Resolution = Width x Height

35
Q

What is the formula to calculate the sound file size

A

Sample Rate x Duration in seconds x Bit Depth

36
Q

How to convert Denary to binary and binary to Denary

A

Use the table

37
Q

What is an overflow error

A

An overflow error occurs when the result of a binary addition exceeds the available bits

38
Q

What is hexadecimal

A

Hexadecimal is a number system that is made up of 16 digits

39
Q

A left shift …

A

multiplies a binary number by 2 (x2)

40
Q

A right shift …

A

divides a binary number by 2 (/2)

41
Q

What is a character set

A

A character set is a defined list of characters that can be understood by a computer

42
Q

What are the Two common character sets

A

-ASCII
-UNICODE

43
Q

What is ASCII

A
44
Q

What are Limitations of ASCII

A

has a limited number of characters which means it can only represent the English alphabet, numbers and some special characters

45
Q

What is UNICODE

A

UNICODE is a character set and was created as a solution to the limitations of ASCII

46
Q

What are the properties of UNICODE

A

-UNICODE uses a minimum of 16 bits, providing 216, representing 65,536 characters
-UNICODE can represent characters from all the major languages around the world

47
Q

What are the properties of ASCII

A

ASCII uses 7 bits, providing 27 unique codes (128) or a maximum of 128 characters it can represent

48
Q

What is a bitmap

A

A bitmap image is made up of squares called pixels

49
Q

What is a pixel

A

-A pixel is the smallest element of a bitmap image
-Each pixel is stored as a binary code

50
Q

What is a binary code

A

Binary codes are unique to the colour in each pixel

51
Q

What is resolution

A

Resolution is the total amount of pixels that make up a bitmap image

52
Q

What is colour depth

A

Colour depth is the number of bits stored per pixel in a bitmap image

53
Q

What Is the formula to calculate the amount of colours

A

2^n (n = colour depth)

54
Q

What is the impact of resolution and colour depth

A

As the resolution or colour depth increases, the bigger the size of the file

55
Q

What is metadata

A

Metadata is additional information stored with the image

56
Q

How is sound sampled & stored

A

-analogue sound waves are converted to digital sound waves by Analogue to Digital conversion
-measure the height of the analogue sound wave
-Each sample generates a value which can be represented in binary and stored
-Using the samples a computer is able to create a digital version of the original analogue wave
-The digital wave is stored on secondary storage

57
Q

What is sample rate

A

Sample rate is the amount of samples taken per second of the analogue wave

58
Q

Samples are …

A

-taken each second for the duration of the sound
-The sample rate is measured in Hertz (Hz)

59
Q

What is bit depth

A

Bit depth is the number of bits stored per sample of sound

60
Q

What effect do sample rate and bit depth have on playback quality

A

higher sample rate = more detail, better sound quality
-higher bit depth = bigger range, better sound quality

61
Q

What effect do sample rate and bit depth have on file size

A

-higher sample rate = more data, larger file size
-higher bit depth = more data per sample, larger file size

62
Q

What is compression

A

Compression is reducing the the size of a file so that it takes up less space on secondary storage

63
Q

What is lossy compression

A

Lossy compression is when data is lost in order to reduce the size on secondary storage

64
Q

What are the properties of lossy compression

A

-Lossy compression is irreversible
-Lossy can greatly reduce the size of a file but at the expense of losing quality
-Lossy is only suitable for data where reducing quality is acceptable

65
Q

What is lossless compression

A

Lossless compression is when data is encoded in order to reduce the size on secondary storage

66
Q

What are the properties of lossless compression

A

-Lossless compression is reversible, the file can be returned to its original state
-Lossless can reduce the size of a file but not as dramatically as lossy
-Lossless can be used on all data but is more suitable for data where a loss in quality is unacceptable

67
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A
68
Q
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CC-2224 Computer Science Paper 1 (6 decks)

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