Data representation (Paper 1)

Question 1

What is a bit(b)?

Answer 1

0 or 1 (binary)

Question 2

What is a nibble?

Answer 2

4 bits

Question 3

What is a byte (B)?

Answer 3

8 bits

Question 4

What is a kibibyte (KiB)?

Answer 4

1024 bytes

Question 5

What is a mebibyte(MiB)?

Answer 5

1024 KiB

Question 6

What is a Gibibyte (GiB)?

Answer 6

1024 MiB

Question 7

What is a tebibyte (TiB)?

Answer 7

1024 GiB

Question 8

What is a pebibyte(PiB)?

Answer 8

1024 TiB

Question 9

What is an exbibyte (EiB)?

Answer 9

1024 PiB

Question 10

What is the most significant bit in binary?

Answer 10

The largest number
On a byte it would be 128

Question 11

What is the least significant bit in binary?

Answer 11

The smallest number
On a byte it would be 1

Question 12

What are the numbers 10-15 represented by in hexadecimal?

Answer 12

A-F

Question 13

How would you convert a binary byte into hexadecimal?

Answer 13

.Firstly split the byte into two nibbles
.Then convert each nibble separately and join the results

Question 14

How would you convert hexadecimal into denary?

Answer 14

.Remember that hex is in base 16
.Multiply the hexadecimal value by its place value and add the results

Question 15

Where is hexadecimal used in real life?

Answer 15

.Color values in photo editing software’s and web design
.IPv6 addresses
.Unicode

Question 16

Why is hexadecimal used rather than biary?

Answer 16

Hexadecimal is easier for programmers to remember rather than the binary equivalent

Question 17

What are the rules of binary addition?

Answer 17

0 + 0 = 0
0 + 1 or 1 + 0 = 1
1 + 1 = 0 carry a 1
1 + 1 + 1 = 1 carry a 1

Question 18

When would an overflow occur when adding binary numbers?

Answer 18

-An overflow occurs when the result of adding two binary numbers is greater than the number of bits allowed
-If the number falls out of the limit an overflow error is returned

Question 19

Explain the effect on performing a binary right shift of two places on the number 11010110

Answer 19

-Each right shift will divide the number by 2
-so a two place right shift will divide the number by 4
-However, if the shift results in one more 1’s being lost at the right end the results will lose precision

Question 20

How would you convert a negative denary number to binary?

Answer 20

.Convert the number into binary like it was positive
.Flip the bits
.Add one
.Convert

Question 21

How would you convert a negative two’s complement binary number to denary?

Answer 21

.Flip the bits
.Add one

Question 22

What is a signed representation of a binary number?

Answer 22

A signed integer can represent both positive and negative

Question 23

What is an unsigned representation of a binary number?

Answer 23

Unsigned means it can only represent a positive integer

Question 24

What is a character set?

Answer 24

A set of digits, symbols and letters that can be represented by a computer

Question 25

How many characters can be represented by a 7 bit ASCII character set?

Answer 25

128

Question 26

State was is meant by extended ASCII

Answer 26

Extended ASCII uses 8 bits rather than 7. this allows up to 256 characters to be represented

Question 27

What is unicode?

Answer 27

Unicode uses 16 bits per character and can represent 65,536 different characters

Question 28

What is the sample rate?

Answer 28

The number of samples taken per second in hertz

Question 29

What is sample resolution

Answer 29

-The number of bits per sample -A higher sample resolution enables more accuracy however a bigger file size

Question 30

What is the formula for the sound file size?

Answer 30

Sound file size (bits) = Sample rate x sample resolution x seconds

Question 31

What is a pixel?

Answer 31

The smallest identifiable area of an image each appearing as a square of a single colour

Question 32

What is image resolution?

Answer 32

The number of pixels in the image

Question 33

What is the colour depth when there are 2 colours?

Answer 33

1 bit per pixel required

Question 34

What is the colour depth when there are 4 colours?

Answer 34

2 bits per pixel required

Question 35

What is the colour depth when there are 8 colours?

Answer 35

3 bits per pixel required

Question 36

What is the colour depth when there are 16 colours?

Answer 36

4 bits per pixel required

Question 37

What is the formular for image size?

Answer 37

(Height x width x colour depth) ÷ 8 bits = file size in bytes

Question 38

What is file compression and why is it used?

Answer 38

.File compression uses algorithms to remove repeated and unnecessary data .This is so that the file size can be reduced

Question 39

Which formats are Lossy compression?

Answer 39

JPG, MP3, WMV, MPG

Question 40

What are the examples of lossy compression?

Answer 40

.Smallest file sizes which reduce transmission time .Reduces internet traffic and collisions

Question 41

What are the disadvantages of lossy compression?

Answer 41

Detail is permanently lost by reducing colour depth, resolution or sample rate

Question 42

What are some generic examples of lossy compression?

Answer 42

Music streaming Online images and videos Image libraries on devices in the cloud

Question 43

What are the formats of lossless compression?

Answer 43

TIF, PDF, GIF, PNG, ZIP

Question 44

What are the advantages of lossless compression?

Answer 44

Original quality is preserved No data or information is lost

Question 45

What are the disadvantages of lossless compression?

Answer 45

Less significant reduction in the file size

Question 46

What is the maximum range in twos complement with 8 bits

Answer 46

-128 to 127

Question 47

How many possible combinations are there in a binary byte?

Answer 47

256

Question 48

Why do computers use binary?

Answer 48

As all data that the computer systems transfer is sent by electrical signals which can be in 2 states on or off. As there are only 2 states it is all used as binary data

Question 49

Why might a programmer prefer to use hexadecimal?

Answer 49

As each hexadecimal digit is 4 binary digits therefore making it easier to understand

Question 50

What is unicode?

Answer 50

Code that uses 16 bits per character and can represent 65,536 different characters

Question 51

What is extended ASCII?

Answer 51

Uses 8 bits rather than 7 which allows up to 156 characters to be represented

Question 52

What happens when you increase the colour depth or bit depth on an image?

Answer 52

The quality increases aswell as the file size

Question 53

Why is compression neccesary?

Answer 53

To reduce the size of the file

Question 54

How does lossless compression compress data?

Answer 54

-By using run length encoding and frequency pairs to encode each run length of the same coloured pixel