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Computer Science > Organisation and structure of data #4 > Flashcards

Organisation and structure of data #4 Flashcards

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1
Q

What are the 3 different counting systems in computers?

A

Denary
Binary
Hexadecimal

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2
Q

How does denary work?

A

also known as the base₁₀ counting system. the digits 0₁₀ 1₁₀ 2₁₀ 3₁₀ 4₁₀ 5₁₀ 6₁₀ 7₁₀ 8₁₀ 9₁₀ are used to represent umbers.

eg. 138₁₀ means
1 ‘hundred’
3 ‘tens’
8 ‘units’

giving the total number 138

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3
Q

How does binary work?

A

‘B’inary digI’Ts’, also known as BITs

a BIT is either a 1₂ or 0₂

you may think of this as a light switch, where if the switch is on, it is stored as the digit 1
if the switch is off, its stored as the digit 0

IT IS BASE 2 COUNTING SYSTEM

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4
Q

How does hexadecimal work?

A
  • Also known as the base₁₆ counting system.

the digits 0₁₆ 1₁₆ 2₁₆ 3₁₆ 4₁₆ 5₁₆ 6₁₆ 7₁₆ 8₁₆ 9₁₆ represent 1-9

the characters A₁₆ B₁₆ C₁₆ D₁₆ E₁₆ F₁₆ represent 10-15

e.g. 8A₁₆ means
8 ‘sixteens’
10 ‘units’

giving the total number 138

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5
Q

How to perform Denary to binary?

A

Create a base 2 table
(somewhat ok representation)

128|64|32|16|8|4|2|1|
[ ][ ][ ][ ][ ][ ][ ][ ]

To convert 198₁₀ into binary, it’ll just look like this

128|64|32|16|8|4|2|1|
1 1 0 0 0 1 1 0

11000110₂

Hopefully self explanatory, like they all add up 198

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6
Q

How to perform Denary to hexadecimal?

A

Create a base 16 table
(somewhat ok representation)

256|16|1
[ ][ ][ ]

To convert 198₁₀ think about the hexadecimal digits and characters

256|16|1
0 C 6

Adds up to 198 and also it would be C6₁₆

(you should have a calculator, now its just all up to your maths skills)

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7
Q

How to perform Binary to denary?

A

Create base 2 table
(insert the binary in table)

00100011₂

128|64|32|16|8|4|2|1|
0 0 1 0 0 0 1 1

and ye thats 35₁₀

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8
Q

How to perform Binary to hexadecimal?

A

Create base 2 table
(insert the binary in table)

00101011₂

128|64|32|16|8|4|2|1|
0 0 1 0 1 0 1 1

Split it to 4-bit base 2 tables

128|64|32|16—————–8|4|2|1|
0 0 1 0——————1 0 1 1
=
8|4|2|1|—————-8|4|2|1|
0 0 1 0——————-1 0 1 1

Think about hexadecimal digits and characters
= 2B₁₆

256|16|1
0 2 B

”-“ = fuuuuuucking space

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9
Q

How to perform Hexadecimal to denary?

A

Create base 16 table
(insert hexadecimal in table)

C6₁₆

256|16|1
0 C 6

Then multiply each heading

C(12) x 16 = 192₁₀
6 x 1 = 6₁₀

192₁₀+6₁₀
= 198₁₀

^^^^ the denary number

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10
Q

How to perform hexadecimal to binary?

A

Create 2 4-bit base 2 tables

8|4|2|1|————– 8|4|2|1|
[] [] [] [] ————— [] [] [] []

Convert hexadecimal number 2B₁₆
start with 2

8|4|2|1|—————-8|4|2|1|
0 0 1 0 —————- [] [] [] []

then B (think about hexadecimal digits and characters)

8|4|2|1|————— 8|4|2|1|
0 0 1 0 —————–1 0 1 1

connect 4-bit tables as 8-bit table

128|64|32|16|8|4|2|1|
0 0 1 0 1 0 1 1

Binary = 0010101₂

”-“ = space, fucking space

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11
Q

What are arithmetic shift functions?

A

Manipulations of bit patterns for 8-bit registers

(think of it as like x10 or /10)

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12
Q

Arithmetic shift right 01000000₂ by 2

A

01000000₂

00010000₂

You need workings out for the mark sooo idk
write down og denary number to new denary number

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13
Q

Arithmetic shift left 01111001₂ by 1

A

01111001₂

11110010₂

You need workings out for the mark sooo idk
write down og denary number to new denary number

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14
Q

Explain binary addition

A

0₂ + 0₂ = 0₂
1₂ + 0₂ = 1₂
1₂ + 1₂ = 10₂ (which is 0 and a carry of 1)

Remember this

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15
Q

Solve
1₂+11₂= ?

A

Calculations:
____1₂
+ 1 1₂

Start from right then left

1₂ + 1₂ = 10₂ = 0₂ carry 1

Last digit is 0

Next column becomes:

0₂ + 1₂ + 1₂ due to the carried 1

0₂ + 1₂ + 1₂ = 10₂ = 0₂ carry 1

Next digit is 0 but then since theres no other column, 1 remains which is the last digit

answer = 100₂

”-“ = fuckign space

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16
Q

Solve
1010₂ + 11₂ = ?

A

Calculations:
1 0 1 0₂
+ 1 1₂

First column:
0₂ + 1₂ = 1₂
Last digit = 1

Second column:
1₂ + 1₂ = 0₂ carry 1
Next digit = 0₂

Third column:
0₂ + 0₂ + 1₂ = 1₂ (due to carried 1)
Next digit = 1₂

Final column:
1₂ + 0₂ = 1₂ <– final digit

answer = 1101₂

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17
Q

Now solve
100101₂ + 10101₂ = ?

(this time no calculations so idk use a paper)
(u cba to use paper, so u winging this shit)

A

Answer = 111010₂

(Calculations on page 60)

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18
Q

What’s different with sound in terms of signals?

A

It is an analogue signal

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19
Q

How can sound be stored in a pc?

A

Converts into a digital signal to become processed

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20
Q

Whats the method of converting sound into a digital signal?

A

Sampling

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21
Q

What is sampling?

A
  • When hardware (microphone)
  • Measures level of sound
  • Many times per second
  • And records it as binary digits
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22
Q

Look at page 61 for diagram of sampling analogue sound

A

Whatever

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23
Q

What are the 3 digital audio quality?

A

Sample rate
Bit depth
Bit rate

24
Q

Define sample rate

A

Number of audio samples captured each second

25
Q

Define bit depth

A

Number of bits available each clip

26
Q

Define bit rate

A

Number of bits used each second of audio

27
Q

Definition of sampling frequency?

A

Number of times sound level sampled per second

28
Q

Unit for sampling frequency?

A

kHz

29
Q

Higher the sampling freq. = ?

A

Better quality of sound recorded

30
Q

Typical sampling frequency?

A

44,000 kHz

31
Q

How is an image represented by pixels in binary format?

A

Look at page 62.

32
Q

How is a colour bitmap image stored?

A
  • Replacing 1s and 0s with longer number
  • that represents how much red, green and blue (RGB)
  • required in colour of each pixel (colour depth)

Additional info at 62

33
Q

What are vector images in terms of binary?

A
  • Doesn’t store data by pixels
  • Set of instructions for drawing geometric shape
34
Q

2 advantages of vector image?

A
  • Can scale without loss of quality
  • Use less storage space
35
Q

What is metadata?

A

It’s data about data

(info about the data ig?)

36
Q

Why metadata needed for an image file?

A
  • Display key properties for an image
  • Which is needed for pc to render image correctly
37
Q

3 examples of key properties in an image?

A
  • Height
  • Width
  • Colour depth
38
Q

4 examples of a character in terms of binary

A
  • A letter
  • A digit
  • A space
  • A punctuation mark
39
Q

What ASCII stand for?

A

American Standard Code for Information Interchange

40
Q

What are character sets?

A

Table thats maps a character with unique binary number

41
Q

1 example of a character set?

A

ASCII

42
Q

See page 64 for a retarded ass ASCII table

A

Whatever

43
Q

1 disadvantage of ASCII?

A

Can only represent 128 different characters

(Doesn’t have summin like £ cuz american ig?)

44
Q

What is unicode?

A

Standard character set

Originally an extension to ASCII

but pretty much contains alotta characters around the world

45
Q

5 data types?

A
  • Integer
    *Real
  • Boolean
  • Character
  • String
46
Q

Desc and e.g. of
Integer

A
  • Whole numbers, positive/negative

e.g. 42, 11, 0

47
Q

Desc and e.g. of
Real

A
  • Numbers, including fractions/decimal points

e.g. 12.9, -17.50, 28.0

48
Q

Desc and e.g. of
Boolean

A

True/false

e.g. 1 or 0

49
Q

Desc and e.g. of
Character

A
  • Letter, digit, space, punctuation mark, symbol

e.g. ‘A’, ‘b’, ‘7’, ‘?’

50
Q

Desc and e.g. of
String

A
  • A sequence of characters

e.g. ‘Computer science’, ‘The cat sat on the mat’

51
Q

What are data structures?

A
  • Specific way of organising data within memory
  • So it can be processed efficiently
52
Q

What static data structure do?

A
  • Designed to store known number of data items

*Can be changed but mem size fixed

53
Q

Example of static data structure?

A

Array

(I have no idea wtf that is)

54
Q

Advantage and disadvantage of static data structure?

A

+ Easier to program

  • Fixed number of data items
55
Q

What dynamic data structure do?

A
  • Designed to allow data structure
  • To grow/shrink
  • Can add new elements or remove elements

Computer Science (14 decks)

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