Brainscape's Knowledge GenomeTM

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


See full index

A-level Computer Science > SLR 12 - coding texts and graphics > Flashcards

SLR 12 - coding texts and graphics Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

What is character code?

A

a decimal digit to represent a character

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

What does ASCII stand for?

A

American Standard Code for Information Interchange

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

What are the two most widely used information coding systems?

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

How did ASCII develop over time?

A
  • originally had 7 bits (128 different characters)
  • created extended ASCII = 8 bit (256 characters)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What was Unicode?

A

character set that can represent the widest variety of alphabets and symbols universally, using 8 to 48 bits per character

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

What happens when data is transmitted?

A

errors occur due to changes during transmission

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

What are the four different types of error checking?

A
  • parity bit
  • majority voting
  • checksums
  • check digits
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How do parity bits work?

A
  • at the start of the byte you send a parity bit
  • this makes the total number or bits in the binary number odd (odd number of ones) or even (even number of ones)
  • if after transmission the total number of ones is even but you stated the parity was odd you know there has been an error in transmission
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the con of parity bits?

A
  • if one or more bits are wrong the parity bit is ineffective
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is majority voting?

A
  • each bit gets sent three times
  • whichever number occurs most times for each bit is taken as the correct value
  • erroneous data is ignored
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the cons of majority voting?

A
  • There could be an instant where the data is wrong three times
  • Also its no the best as you have to send the data three times so more storage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a checksum?

A
  • you add up the sum of the binary numbers
  • if the sum = the value transmitted then it is correct
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the cons of a checksum?

A

if two pieces or multiple pieces of data change but they still add up to the checksum, it might be wrong but you don’t realise

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

What is a check digit?

A
  • Most commonly in barcodes
  • Normally referred to with ISBN, when you give a device a very long number - ISBN number multiplied by weight
  • Add all the values
  • Divide the value by 10
  • Take the remainder away from 10 and that is your check digit
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How many bits does an RGB colour pallet use?

A

24 bits

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

How do bitmapped images work?

A
  • images are broken into pixels
  • each pixel is assigned a binary value
  • the value assigned to a pixel determines it colour
17
Q

What is image resolution?

A
  • the number of dots per square inch, where a dot is a pixel
  • resolution can also refer to the number of pixels in an image
18
Q

What is the calculation for the number of different pixels that can be represented?

A

2^n

19
Q

What are vector images?

A
  • geometric objects and shapes are used to create images
  • properties for each geometric shape or object in the image are stored within a drawing list
20
Q

What are the pros of a vector image?

A
  • Can be scaled without losing quality
  • Well suited to simple images which use shapes but no good for photograph
  • Frequently use less storage space than bitmapped graphics
21
Q

Pros of bitmap images?

A
  • Used for storing photographs
  • Often use more storage space than vector graphics
22
Q

How do computers represent sound?

A

as a sequence of samples, each taking a discrete digital value

23
Q

What is a sampling rate and what is it measured in?

A

the number of samples per second (hertz)

24
Q

How do you calculate the file size of an image?

A

pixel length x pixel width x colour depth

25
Q

What is bitmap metadata?

A
  • data about data
  • it stored alongside bits which make up the image and increase the overall file size
26
Q

What are some examples of bitmap image metadata?

A
  • dimensions
  • colour depth
  • file depth
  • locations
  • creation date
  • last modified date
  • author
  • etc.
27
Q

What do you need to store about a vector image?

A
  • coordinates for the centre of the circle
  • radius
  • fill colour
  • outline colour
  • outline width
28
Q

What are vector graphics usually used for?

A

simple images like company logos
can’t be used for photographs

A-level Computer Science (11 decks)

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