1.3 Data storage and compression

Question 1

bit

Answer 1

Short for binary digit.
It is the smallest unit of data that is represented in a computer.
It has a single binary value 1 or 0

Question 2

nibble

Answer 2

equals to 4 bits (half a byte)

Question 3

byte

Answer 3

equivalent to 8 bits

Question 4

1 kibibyte (KiB)

Answer 4

(2^10) equivalent to 1024 bytes

Question 5

mebibyte (MiB)

Answer 5

2^20 equivalent to 1024 x 1024 (1024^2) bytes

Question 6

gibibyte (GiB)

Answer 6

2^30 equivalent to 1024 x 1024 x 1024 (1024^3) bytes

Question 7

1 tebibyte TiB

Answer 7

2^40 equivalent to 1024 x 1024 x 1024 x 1024 bytes

Question 8

1 pebibyte PiB

Answer 8

equal to 2^50 bytes

Question 9

exbibyte (EiB)

Answer 9

EiB is equal to 2^60 bytes

Question 10

acronym for memory size

KMGTPE

Answer 10

King Mark Gave Ten Powerful Elephants”

King = KiB = 2^10 bytes
Mark = MiB = 2^20 bytes
Gave = GiB = 2^30 bytes
Ten = TiB = 2^40 bytes
Powerful = PiB = 2^50 bytes
Elephants = EiB = 2^60 bytes

as u go down divide

Question 11

The file size of an image is calculated as

Answer 11

image resolution (in pixels) × colour depth (in bits)

Question 12

The size of a mono sound file is calculated as

Answer 12

sample rate (in Hz) × sample resolution (in bits) × length of sample (in seconds)

Question 13

For a stereo sound file

Answer 13

you would then multiply the result by two.

Question 14

Benefits of reducing the size of a file

Answer 14

• reduces storage space required
• reduce transmission time
• quicker to upload/download the file
• less bandwidth required for transmission

Question 15

There are 2 types of compression:

Answer 15

lossy and lossless file compression

Question 16

Lossy Compression:

Answer 16

-Lossy compression reduces the file size by permanently removing some data from the file e.g reducing resolution or colour depth, reducing sample rate or resolution

mp3- sound, mp4- video, jpeg- image

Question 17

Lossless

Answer 17

A compression algorithm is used to reduces the file size without permanently removing any data

Question 18

Run length encoding (RLE)

Answer 18

replaces sequences of repeated characters with a code that represents the character and the number of times it is repeated

Question 19

How image files are compressed (lossy)

Answer 19

• a compression algorithm is used
• colour depth may be reduced (colours that the human eye cannot see are removed)
• image resolution may be reduced

Question 20

How sound files are compressed (lossy)

Answer 20

• a compression algorithm is used
• sounds that cannot be heard by the human ear are removed
• sample rate may be reduced
• sample resolution may be reduced

Question 21

How text files are compressed (lossless)

Answer 21

• a compression algorithm called run length encoding (RLE) is used
• no data is removed
• repeating characters patterns are identified and indexed

Question 22

differences

Answer 22

lossless file size will be larger so it may take longer to upload