Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

GCSE Computer Science > Data Representation (PAPER 1) > Flashcards

Data Representation (PAPER 1) Flashcards

You may prefer our related Brainscape-certified flashcards:
GCSE Religious Studies - Edexcel Route A flashcards GCSE Religious Studies - Eduqas Route A flashcards GCSE Geography - AQA flashcards Biology 101 flashcards GCSE Religious Studies - Edexcel Route B flashcards GCSE Religious Studies - Eduqas Route B flashcards
1
Q

What is a bit
- What two characters represent bits
- What do each of these two show
- What does bit stand for

A

the smallest measurement of data
- 1 and 0
- 1 shows electricity is flowing, 0 shows it is not flowing

  • Binary digit
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 8 commonly used units of data
- how do their sizes compare
- What are their symbols

A

Bit - b
Nibble - 4 bits
Byte - B - 8 bits
Kilobyte - kB - 1000 / 1024 bytes
Megabyte - MB - 1000 / 1024 Kilobytes
Gigabyte - GB - 1000 / 1024 Megabytes
Terabyte - TB - 1000 / 1024 Gigabytes
Petabyte - PB - 1000 / 1024 Terabytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How many values can a nibble take
- How many can a byte take

A

Nibble - 2^4 = 16 values
Byte - 2^8 = 256 values

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the binary and hexadecimal numbers from 0 - 15

A

D = B = H

0 = 0 = 0
1 = 1 = 1
2 = 10 = 2
3 = 11 = 3
4 = 100 = 4
5 = 101 = 5
6 = 110 = 6
7 = 111 = 7
8 = 1000 = 8
9 = 1001 = 9
10 = 1010 = A
11 = 1011 = B
12 = 1100 = C
13 = 1101 = D
14 = 1110 = E
15 = 1111 = F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Which bit has the largest value
- which has the least value

A

The left most bit
- the right most bit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the value 00110101 in denary

A

53

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the value 79 in binary

A

01001111

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is 10001101 + 0100100 (binary)

A

11010101

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is an overflow error

A

When a number has too many bits - a result requires more bits than the CPU is expecting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Which bit will be the first to overflow
- Where will these extra bits be stored
- What is used to show that an overflow error has occured

A
  • The left most bit - most significant
  • Elsewhere
  • Overflow flags
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Add the binary numbers below, giving the answer as an 8-BIT BINARY NUMBER

11010001 + 10010100

A

101100101

REMOVE THE LEFT MOST BIT

01100101

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a binary shift
- What happens when a binary number is multiplied by 2, what can it cause
- What happens when a binary number is divided by 2, what can it cause

A

When every bit in a binary number is moved left or right by a certain number of places
- left shift by 1 place, can cause overflow errors
- right shift by 1 place, can cause bits to ‘drop off’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What identifies how many places a bit moves during a binary shift

A

The power of 2 that a number is being divided / multiplied by

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

multiply 00101001 by 8

A

8 = 2^3
3 place shift to the left

001,01001000 ; [001] will overflow

01001000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

divide 00111100 by 4

A

4 = 2^2
2 place shift to the right

00001111,00 ; [00] will drop off

00001111

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the alternative name for hexadecimal

A

Base - 16

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What denary numbers can a single hex character represent
- How many bits equate to a single hex character

A

0 - 15
- 4 bits (a nibble)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the hex number 87 in denary

A

135

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the denary number 106 in hexadecimal

A

6A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Why do programmers prefer using hex when coding

A
  • easier to remember large numbers
  • less chance of input errors
  • easier to convert between binary and hex than binary and denary
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does moving left one space do to the place values in hex

A

multiply by 16

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the steps to converting a binary number to hex

A
  • split binary number into nibbles
  • convert each nibble to hex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is 10111001 in hexadecimal

A

B9

24
Q

What is 111110 in hexadecimal

A

3E

25
Q

What is 8C (hex) into binary

A

10001100

26
Q

What is a character set

A

a collection of characters that a computer recognises from their binary representation

27
Q

How does pressing a button on a keyboard translate to a character on a computer

A

pressing the button gives a binary signal to the computer saying which key is pressed
- computer then uses character set to translate the binary code into a character

28
Q

What are the two most common character sets
- How many bits are used for each
- What characters are able to be represented by each

A
  • ASCII and Unicode
  • 7 bits for ASCII, with an extra 0 at the front to make it one byte,
    Multiple bytes per character for Unicode
  • ASCII represents all English letters, numbers, symbols and commands
    Unicode aims to store every single possible character including different alphabets (Greek, Russian etc. )
29
Q

What is the formula for file size of a text file

A

file size (bits) = number of bits per character x number of characters

30
Q

How are images made / stored

A

as a series of pixels (bitmap)

31
Q

How are colours within a image represented

A

as a binary code

32
Q

how many bits are required for each pixel for a black and white image

A

1 bit - 0 for white and 1 for black

33
Q

How can a greater range of colours be available in an image

A

by increasing the number of bits for each pixel

34
Q

What is the colour depth

A

the number of bits used for each pixel

35
Q

How can you work out the amount of colours available from the colour depth

A

total number of colours = 2^ colour depth

36
Q

how many colours are available for a
- 1 bit image
- 4 bit image
- 6 bit image

A
  • 2^1 = 2
  • 2^4 = 16
  • 2^6 = 64
37
Q

What colour depth do most modern devices use
- how many colours are available
- how are they split among red, green and blue

A

24 bit colour depth - 16 777 216 colours
- 8 bits each for red, green and blue

38
Q

What is the image resolution
What is the formula for image resolution

A

the number of pixels in the image
- width x height

39
Q

What is the formula for the file size of an image

A

file size (bits) = image resolution x colour depth

40
Q

What is the file size in MB of an 8 bit image that is 2000 pixels wide and 1000 pixels high

A

2000 x 1000 x 8 = 2000000 x 8 = 16000000

16000000 / 8 = 2000000 bytes
2000000 / 1000 = 2000 KB
2000 / 1000 = 2MB

41
Q

What is metadata
- what does it include

A

The information stored in an image file which helps the computer recreate the image
- file format, height, width, colour depth
- can also include date and time of creation or last edit

42
Q

How is sound recorded by a microphone

A

as analogue signals

43
Q

What are analogue signals

A

pieces of continually changing data

44
Q

What must happen to analogue signals before they can be read by a computer
- what technology is required for this
- what is this process called

A

it must be converted into digital data
- analogue to digital converters
- sampling

45
Q

How is an analogue signal converted to digital data

A
  • samples are taken of the signal at regular intervals
  • the curve is created digitally (looks similar to bar graph)
46
Q

What is the issue with digital data
- how can this be improved

A
  • it isn’t continuous - lots of data gets lost
  • by taking samples more often
47
Q

What is the sample rate
- what is it measured in

A

the amount of samples taken per second
- Hz (Hertz) / KHz (Kilohertz)

48
Q

What is Bit Depth

A

the number of bits available for each sample

49
Q

What is the formula for bit rate

A

sample rate x bit depth

50
Q

What is the formula for file size of a sound file

A

file size (bits) = sample rate (Hz) x bit depth x length (s)

51
Q

How does increasing the sample rate affect the sampled sound

A

it will be better quality and a closer match to the original recording

52
Q

How does increasing the bit depth affect the sampled sound

A

the file will pick up quieter sounds resulting in a sampled sound closer to the original recording

53
Q

What is data compression
- Why is it used (4)

A

When file sizes are made smaller while trying to make the compressed file as true to the original as possible
- take up less storage space
- streaming / downloading is quicker as less bandwidth is used
- web pages load more quickly
- email services normally have restrictions on sizes of attachments

54
Q

What are the two types of compression
- how do they work

A

Lossy - permanently removes data from the file
Lossless - temporarily removes the file while storing and restores it to its original state when opened

55
Q

What are the pros and cons of lossy compression

A

P - greatly reduced file size, less bandwidth to download, can be read by lots of software
C - loses data permanently, can’t be used on software or text files, worse quality

56
Q

What are the pros and cons of lossless compression

A

P - data is only temporarily lost, can be decompressed, can be used on text and software files
C - only a slight reduction in file size

GCSE Computer Science (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions