Data Representation (paper 1)

Question 1

what is the order for the memory size

Answer 1

bit
nibble
byte
kibibyte
mebibyte
gibibyte
tebibyte
pebibyte
Bob Nibbled Bens Keish Made Gratefully To Paul

Question 2

How many bits is in a byte

Answer 2

8

Question 3

how many bits are in a nibble

Answer 3

4 bits (half a byte)

Question 4

how many bytes are in a kibibyte

Answer 4

1024

Question 5

how many bytes are in a mebibyte

Answer 5

1024 x 1024

Question 6

how many bytes in a gibibyte

Answer 6

1024 x 1024 x 1024

Question 7

how many bytes in a tebibyte

Answer 7

1024 x 1024 x 1024 x 1024

Question 8

how do you work out how many mebibytes are in a value

Answer 8

divide it by 1024 x 1024

Question 9

what is denary

Answer 9

the 10 number base number system (0-9)

Question 10

what is binary

Answer 10

the 2 number base number system using the digits 0 and 1 and place values 1, 2, 4, 8, 16…

Question 11

why do we use binary to represent data in computers

Answer 11

becuase anything further would make the data hard to deal with and possibly cause error, it is simpler being one of two values

Question 12

what is one of the benefits of binary

Answer 12

takes up less storage so it makes computers cheaper and more reliable

Question 13

what is hexadecimal

Answer 13

the base 16 number system that uses the values 0-9 and A-F

Question 14

how do you convert a denery number to binary

Answer 14

divide it by 2 and take the answer or remainer and repeat with the answer

Question 15

Which bit is most significant in binary

Answer 15

the biggest

Question 16

what does CPU stand for

Answer 16

central processing unit

Question 17

what does a CPU do

Answer 17

store data in registers

Question 18

why do overflow errors occur when adding binary

Answer 18

because if the result is greater than 255 then another bit is needed

Question 19

what makes hexadecimal to binary easier

Answer 19

each value cna be taken into 4 binary bits and then just put the bits together

Question 20

how do you convert denary to hexadecimal

Answer 20

divide the denary by 16 and then take the remainder and divide the result again

Question 21

what is a sign bit

Answer 21

when all the other bits of the binary are negative

Question 22

what is two’s complement

Answer 22

when only the MSB is the negative placeholder

Question 23

how do you convert nagtive denary numbers into binary using two’s complement

Answer 23

• write the binary as normal
• change the 0 to 1 and 1 to 0
• then add one

Question 24

What is the affect when binary shifts left

Answer 24

you multiply but the powers of 2

Question 25

what is the affect when the binary shifts right

Answer 25

you divide by the powers of 2

Question 26

How many places must you shift the binary left to x2

Answer 26

one

Question 27

How many places must you shift the binary left to x4

Answer 27

two

Question 28

How many places must you shift the binary left to x8

Answer 28

three

Question 29

State some uses of hexadecimal coding

Answer 29

- HTML colour codes - MAC addresses

Question 30

why would a programmer prefer hex to binary

Answer 30

- 4 binary numbers = 1 hex = easier to understand and cheaper

Question 31

what is the same given to a digit at the end of a sequence of values to calculate an error

Answer 31

check digit

Question 32

how is a check digit used to detect errors

Answer 32

- value of check digit depends on other digits in sequence - if any numbers in sequence contain an error, the check digit will be incorrect

Question 33

how is text represented

Answer 33

each character on the keyboard has a binary value which is transmitted to the computer each time a key is pressed

Question 34

what is the character set used to represent text in america

Answer 34

ASCII

Question 35

what is a character set

Answer 35

it contains all the characters that are in that character set andd the binary value that is assigned to each character

Question 36

what are the two ways sound can be recorded

Answer 36

- analogue - digital

Question 37

how is sounds recorded

Answer 37

the amiplitude of the wave must be recorded in regualr intervals - more intervals results in a better quality recording - this is called sound sampling

Question 38

how is sound stored in a computer

Answer 38

- analogue sounds must be converted to digital to be stored and processed in a computer - then a digital to analogue converter is used to digital signals into outputs

Question 39

how are images represented

Answer 39

a bitmap is made up of pixels

Question 40

what is a pixel

Answer 40

a very small dot of colour that is displayed with many more others to create an image

Question 41

what colour does 1 represeent

Answer 41

white

Question 42

if more colours represented what happens to the colour(bit) depth

Answer 42

it also increases, as does the file size

Question 43

how do you calculate the sile size in bytes of an image

Answer 43

(width in px x height in px x colour depth) / 8

Question 44

what does the desity of pixels affect

Answer 44

the sharpness of an image = smoother edges and better overall quality

Question 45

what do compression softwares do

Answer 45

use algorithms to remove repeated unneccessary data

Question 46

what is the purpose of useding data compression

Answer 46

- reduce the size of a file on a disk - easier for streaming data over the internet

Question 47

what are the two types of data compression

Answer 47

- lossy - lossless

Question 48

what are the file types which use lossy compression

Answer 48

- JPG - MP3 - WMV - MPG

Question 49

what are the benefits and disadvangtages of lossy compression

Answer 49

+ smaller file sizes + less transmission time + reduces internet traffic -detail is permanently lost by reducing colour depth, resolution or sample rate

Question 50

what are the uses of lossy compression

Answer 50

- music streaming - online images & videos - image libaries

Question 51

what file types use lossless compression

Answer 51

- TIF - PDF - GIF - PNG - ZIP

Question 52

what are the benefits and disadvantages of lossless data compression

Answer 52

+ orignal quality is preserved , no information or data lots -less significant reduction in file size

Question 53

what are the uses of lossless data compression

Answer 53

- text documents - electronic books - high resolution print documents

Question 54

Explain how sampling is used to store audio recordings

Answer 54

Multiple sound samples are taken in regular intivals to record the sound, the higher the sample rate the better the quatlity of the sound, taking analogue values into digital values for storage

Question 55

why do computers use binary

Answer 55

because they have memory and NAND gate circuits which uses values of 0 and 1 to locate things out of storage

Question 56

which number symbolises on

Answer 56

1

Question 57

which number symbolises off

Answer 57

0

Question 58

define binary

Answer 58

a base-2 number system that uses the values 0 and 1

Question 59

what is the benefit of hexadecimal over binary

Answer 59

- hex is easier to read and write - hex is smaller and takes up less space - hex is easier to debug and locate errors

Question 60

what is meant by the term analogue data

Answer 60

a continuous stream of data that is processed by humans

Question 61

what is meant by the term digital data

Answer 61

discrete data that only uses the values of 0 or 1

Question 62

can computers process hexadecimal

Answer 62

no

Question 63

why is A-F used rather than 10-15 in hexadecimal

Answer 63

so only one symbol is needed for the denary number

Question 64

what us meant by the term 'MAC address

Answer 64

a unique address that is given to a computer at the manufactoring stage that can be used to identify the computer

Question 65

give two character sets

Answer 65

- ASCII code - Unicode

Question 66

what is meant by the term 'resolution'

Answer 66

the dimensions of an image (in pixels) it is called metadata

Question 67

what is meant by the term 'metadata'

Answer 67

additional data that is stored with an image that con provide information (dimensions, time and data taken)

Question 68

what is meant by the term 'colour depth'

Answer 68

the number of bits that are used to create each colour in an image

Question 69

what is meant by the term 'lossy compression'

Answer 69

a compression method that reduces the size of a file by permanently removing data

Question 70

what is meant by the term 'lossless compression'

Answer 70

a compression method that reduces the size of a file by temporarily alterning the data

Question 71

explain how a sound file can be compressed

Answer 71

- remove sounds that cannot be heard by the human ear - remove softer sounds played at the same time as loud sounds - this is known as perceptual music shaping

Question 72

what is the process called to compress sound files

Answer 72

perceptual music shaping