Data Representation

Question 1

Nibble

Answer 1

4 bits

Question 2

Byte (B)

Answer 2

8 bits

Question 3

Kilobyte (kB)

Answer 3

1000 bytes

Question 4

Megabyte (MB)

Answer 4

1000 kB

Question 5

Gigabyte (GB)

Answer 5

1000 MB

Question 6

Terabyte (TB)

Answer 6

1000 GB

Question 7

Petabyte (PB)

Answer 7

1000 TB

Question 8

why must data be stored in binary

Answer 8

the computer architecture is built on electrical transistors which can alternate between two states (1/0) very fast

Question 9

sound file size

Answer 9

sample rate x duration (s) x bit depth

Question 10

image file size

Answer 10

colour depth x image height x image width

Question 11

text file size

Answer 11

bits per character x number of characters

Question 12

binary base

Answer 12

base 2

Question 13

how is an analogue sounds wave converted into digital form

Answer 13

the sounds wave is sampled by measuring the amplitude at regular intervals. The samples are stored and the data is converted into binary.

Question 14

overflow error can lead to

Answer 14

loss of data and accuracy

Question 15

over flow error

Answer 15

when the total from adding binary numbers is 9 or more bits which is too big to be stored within the registers of a CPU

Question 16

most significant bit

Answer 16

the bit with the largest value (left-most)

Question 17

least significant bit

Answer 17

the bit with the smallest value (right-most)

Question 18

left binary shift

Answer 18

multiplies, every shift doubles the number

Question 19

right binary shift

Answer 19

divides, every shift halves the number of

Question 20

hex base

Answer 20

base 16

Question 21

each hex character is equal to

Answer 21

a nibble in binary

Question 22

character set

Answer 22

collections of characters that a computer recognises from their binary representation

Question 23

character set egs

Answer 23

unicode, ASCII

Question 24

how many characters can ASCII represent (each character is given a 7-bit binary code)

Answer 24

128 different characters

Question 25

metadata

Answer 25

the aditional information stored in an image file which helps the computer recreate the image on screen from the binary data in each pixel

Question 26

metadata eg

Answer 26

file format, width, colour depth, date

Question 27

colour depth

Answer 27

number of bits used for each pixel

Question 28

image resolution

Answer 28

the number of pixels in the image

Question 29

increasing colour depth and resoultion

Answer 29

increases file size and quality of an image

Question 30

sample rate

Answer 30

how many samples are taken in a second, measured in Hz

Question 31

bit depth

Answer 31

the number of bits available for each sample

Question 32

increasing sample rate or bit depth

Answer 32

increases the file size and improves the quality (closer quality to the original recording)

Question 33

analogue sounds are stored in

Answer 33

binary

Question 34

duration

Answer 34

how many seconds of audio the sound file contains

Question 35

lossy compression

Answer 35

permanently removing data from the file

Question 36

lossless compression

Answer 36

makes the file smaller temporarily by removing data, then restores it to its original state when opened

Question 37

need for compression

Answer 37

-files take up less storage space -downloading files is faster -allows you to send the same content with a much smaller file size

Question 38

lossy pros

Answer 38

-reduced file size -takes up less bandwidth -commonly used

Question 39

lossy cons

Answer 39

-loses data permanently -can’t be used on text or software files -worse quality then the original

Question 40

lossless pros

Answer 40

-no reduction in quality -can be turned back to the original -can be used on text and software files

Question 41

lossless cons

Answer 41

only a slight reduction in file size

Question 42

e.g of lossy file type

Answer 42

MP3, JPEG

Question 43

e.g of lossless file type

Answer 43

PNG