Data Representation

Question 1

base of denary

Answer 1

10

Question 2

base of binary

Answer 2

2

Question 3

base of hexadecimal

Answer 3

16

Question 4

why do computer systems use hexadecimal

Answer 4

Hexadecimal is easier for humans to understand than binary, as it is a shorter representation of
the binary. It is used to represent colour and simplify binary

Question 5

how to converted negative binary (two’s complement) to denary?

Answer 5

add all as normal and add result from -128

Question 6

what happens when you shift one left

Answer 6

number multiplies by 2

Question 7

what happens when you shift one right

Answer 7

number divides by 2

Question 8

what does ASCII stand for

Answer 8

american standard code for information interchange

Question 9

how many bits does ASCII have

Answer 9

7 - represents 128 characters

Question 10

how many bits does ASCII extended have

Answer 10

8 - represents 256 characters

Question 11

how many bits does unicode use

Answer 11

8 to 32 bits (larger files occupy more space)

Question 12

available character sets in unicode

Answer 12

letters, numbers, symbols, emojis non-visual

Question 13

why is a sound wave sampled

Answer 13

to be converted to binary

Question 14

what is sampling

Answer 14

process performed by computer to convert analogue to digital waves

Question 15

if more analogue waves are sampled…

Answer 15

….more data is gathered

Question 16

what are analogue waves compared to digital

Answer 16

analogue = continuous
digital = discrete

Question 17

what is sample rate

Answer 17

number of samples taken in a second

Question 18

what is sample resolution

Answer 18

number of bits per sample

Question 19

how does accuracy of recording and file size increase

Answer 19

as sample rate and resolution increase

Question 20

what is an image

Answer 20

series of pixels that are converted to binary, which is processed by a computer

Question 21

what is bit depth

Answer 21

how many bits are used to store the colours in each pixel of the image

Question 22

what is resolution

Answer 22

number of pixels in image

Question 23

what is colour depth

Answer 23

number of bits used to represent each colour

Question 24

file size and quality of image increases as

Answer 24

the resolution and colour depth increases

Question 25

measurements for data storage

Answer 25

• bits
• nibble (4 bits)
• bytes (8 bits)
• kibibyte (1024 bytes)
• mebibyte (1024 kibibytes)
  – gibibyte (GiB)
  – tebibyte (TiB)
  – pebibyte (PiB)
  – exbibyte (EiB)

Question 26

what does compression do

Answer 26

reduces size of file

Question 27

what is lossless compression

Answer 27

reduces file size without permanent loss of data

Question 28

example of lossless compression

Answer 28

run length encoding (RLE)

Question 29

what is lossy compression

Answer 29

reduces file size by permanently removing data

Question 30

example of lossy compression

Answer 30

reducing resolution of colour depth

Question 31

reasons for data compression to occur

Answer 31

• save storage capacity
• speed up file transfer
• decrease cost for hardware

Question 32

How and why do computers use binary to represent all forms of data

Answer 32

• Any form of data needs to be converted to binary
  to be processed by a computer
• Data is processed using logic gates and stored in
  registers

Question 33

Concept of overflow and why
it occurs in binary addition

Answer 33

• An overflow error will occur if the value is greater
  than 255 in an 8-bit register
• A computer or a device has a predefined limit
  that it can represent or store, for example 16-bit
• An overflow error occurs when a value outside
  this limit should be returned

Question 34

How and why are ASCII and Unicode used

Answer 34

• Text is converted to binary to be processed by a
  computer
• Unicode allows for a greater range of characters
  and symbols than ASCII, including different
  languages and emojis
• Unicode requires more bits per character than
  ASCII