Data Representation

Question 1

Lowest to highest: terabyte, kilobytes, nibble, petabyte, gigabyte, byte, bit

Answer 1

Bit, nibble, byte, kilobyte, megabyte, gigabyte, terabyte, petabyte
FROM BYTE THEY ALL GO UP IN 1000

Question 2

Binary arithmetic rules:

Answer 2

0+0=0
1+0=1
1+1=0 carry the 1
1+1+1=1 carry the 1

Question 3

Advantages of hexadecimal:

Answer 3

-simpler to remember
-quicker to write or type
-less likely to make an error
-easy to convert between hex and binary

Question 4

Overflow error

Answer 4

When the result of an addition is too large for the number of bits the computer works with.

Question 5

Character set

Answer 5

A set of letters, symbols and digits that can be represented by a computer

Question 6

ASCII

Answer 6

American standard code for information interchange. 128 characters into 7 bit binary codes

Question 7

Unicode

Answer 7

To represent other characters for other languages, 16 bits, 65536 possible combinations

Question 8

5 different file formats for images:

Answer 8

-JPG, joint photographic experts group
-BMP, bitmap, uncompressed
-GIF, graphics interchange format
-TIFF, tag image file format
-PNG, portable networks graphics, loddless compression

Question 9

Pixel

Answer 9

The smallest identifiable area of an image

Question 10

Resolution

Answer 10

The concentration of pixels within a specific area

Question 11

Increasing the number of colours:

Answer 11

More bits per pixel = more colour combinations

Question 12

Bit depth

Answer 12

The number of colours that can be represented. Each pixel can represent a finite number of colours, a pixel is attributed a number of n bits.
The number of combinations (2 to the n) dictates the bit depth

Question 13

Colour depth

Answer 13

Colours depth = bit depth

Question 14

Metadata

Answer 14

Data about data, e.g. author, date created, dimensions

Question 15

Bitmap images

Answer 15

Bitmap images are made up of PICture ELement or pixels

Question 16

Bitmap images

Answer 16

Bitmap images are made up of PICture ELement or pixels

Question 17

Analogue sound

Answer 17

Continuous

Question 18

Digital sound

Answer 18

Discrete, repeatedly measuring and recording the sound wave

Question 19

Analogue to digital converters

Answer 19

Sounds must be converted into a digital form in order to be stored and processed by a computer

Question 20

ADC

Answer 20

Analogue to digital converter

Question 21

DAC

Answer 21

digital signals to outputs

Question 22

Sound sampling

Answer 22

Sound sample is a measurement of a sound wave at a given time

Question 23

Sampling rate

Answer 23

Frequency or sample rate per second affects the level of detail in the digital representation. Number of samples per second

Question 24

Sound file sizes

Answer 24

Sample rate x bit depth x duration

Question 25

Digitised sound quality:

Answer 25

-improves the more frequently we sample the sound -improves the more accurate we record the wave height

Question 26

Lossy compression

Answer 26

JPG, GIF, MP3. Permanently looses some data, cannot do back to original data.

Question 27

Lossless compression

Answer 27

Will not lose any of the original data. Algorithm finds groups of repeating patterns and records that as the data.

Question 28

Benefits of compression:

Answer 28

-smaller files=fewer packets=faster transmission time -quicker to complete transmission -reduces download time -images inside web pages appear faster -reduces space on disk/servers

Question 29

Bit rate

Answer 29

Amount of data used to represent one second of audio

Question 30

JPEG

Answer 30

Joint photographic experts group, lossy compression for digital images