Data representation

Question 1

Bit

Answer 1

fundamental unit of information in the form of a single 1 or 0

Question 2

Byte

Answer 2

a group of 8 bits

Question 3

Nibble

Answer 3

a group of 4 bits

Question 4

Kibibyte

Answer 4

2^10 bytes

Question 5

Mebibyte

Answer 5

2^20 bytes

Question 6

Gibibyte

Answer 6

2^30 bytes

Question 7

Tebibyte

Answer 7

2^40 bytes

Question 8

ASCII code

Answer 8

American Standard Code for Information Interchange - code that defines how keyboard characters are encoded into digital strings of ones and zeros

Question 9

Unicode

Answer 9

symbol that enables most of the languages in the world to be symbolised with a special character identification

Question 10

Parity bit

Answer 10

an additional bit that is transmitted as part of a byte to make the total number of ones odd (odd parity) or even (even parity) - data transmitted can be checked by counting the number of ones in a character code to check that there have been no errors during transmission

Question 11

Majority voting

Answer 11

system which requires each bit to be sent three times - if a bit value is flipped incorrectly during transmission over a heavy trafficked line, receiving computer uses majority rule and assumes the two bits have not changed and were therefore correct

Question 12

Checksums

Answer 12

involve adding a mathematical algorithm to the transmitted data; block of (transmitted) data used to create a checksum value which is transmitted with the block - same algorithm is applied to the block after transmission and if the two checksums match, the transmission is considered successful

Question 13

Check digits

Answer 13

additional digit at the end of a string of other numbers designed to check for mistakes in input or transmission

Question 14

Natural number

Answer 14

whole numbers used for counting

Question 15

Rational number

Answer 15

any number that can be written as a fraction or decimal - includes all integer values

Question 16

Irrational number

Answer 16

cannot be expressed as a ratio of two integers or as a repeating or terminating decimal - Pi or any square root of an imperfect square are considered irrational

Question 17

Ordinal number

Answer 17

numbers that describe position or order

Question 18

Number bases

Answer 18

the number of different digits or combination of digits and letters that a system of counting uses to represent numbers

Question 19

Real number

Answer 19

all rational and irrational numbers

Question 20

Compression

Answer 20

a sequence of steps that are followed to reduce file size

Question 21

Lossy compression

Answer 21

data compression technique that results in a loss of data

Question 22

Lossless compression

Answer 22

data compression technique in which no data is lost

Question 23

Run Length Encoding (RLE)

Answer 23

type of lossless compression that works by specifying the number of times a character or pixel colour repeats followed by the value of the character or pixel

Question 24

Dictionary-based compression

Answer 24

type of lossless compression that uses a dictionary to replace repeated phrases with shorter binary strings

Question 25

Encryption

Answer 25

transformation of data from one form to another to prevent unauthorised (third) parties from being able to understand it

Question 26

Plaintext

Answer 26

normal text that has not been encrypted

Question 27

Ciphertext

Answer 27

data or information that has been encrypted

Question 28

Cipher

Answer 28

encryption method or algorithm

Question 29

Key

Answer 29

secret information to lock or unlock the encrypted message

Question 30

Vernam cipher

Answer 30

substitution cipher in which each character is encrypted using its own key

Question 31

Caesar cipher

Answer 31

substitution cipher that works by shifting letters of alphabet along by a given number of characters

Question 32

Sampling rate

Answer 32

number of samples taken per second when sound is recorded

Question 33

Sound sample size

Answer 33

file size (in bits) = sampling rate x seconds x sample resolution

Question 34

Nyquist theorem

Answer 34

states that sampling rate has to be at least twice the highest frequency of original signal

Question 35

Monophonic

Answer 35

just one track of sound/single transmission path

Question 36

Stereophonic

Answer 36

contains two different channels of transmission to add impression of positioning and direction to recording

Question 37

MIDI (Musical Instrument Digital Interface)

Answer 37

set of standards that are used to represent music in digital form

Question 38

Colour depth

Answer 38

The number of bits used to represent the colour of a single pixel

Question 39

Image resolution

Answer 39

number of pixels per inch or centimetre/size of a bitmapped graphic in pixels (width x height in pixels)

Question 40

Bitmap images

Answer 40

images created using a grid of small squares called pixels

Question 41

Metadata

Answer 41

data that describes data

Question 42

Image file size

Answer 42

width x height x colour depth