Paper 2 - Data Representation

Question 1

Logic Gates:

Answer 1

Special Circuits built into computer chips, receive binary data and perform a Boolean Operation.

Question 2

Not Gate:

Answer 2

Outputs opposite input

Question 3

And Gate:

Answer 3

If both inputs are 1 the output is 1 otherwise it is always 0

Question 4

Or Gate:

Answer 4

if one or more inputs are 1 then the output is 1 otherwise the output is 0

Question 5

Parity Bits

Answer 5

The check digit used for binary data; The check digit is added to make the binary either have an even or odd number of 1’s, if one bit is read incorrectly the computer will pick out the error. If two bits are read incorrectly then no error will be detected.

Question 6

What is Denary?

Answer 6

A number system with ten digits (1-9)

Question 7

What is Binary?

Answer 7

Only uses two different digits- also known as base-2.

Right to Left values go up by powers of 2.

Question 8

What is left shift?

Answer 8

Multiplying Binary by 2 to the a the power of spaces moved.

Question 9

What is right shift?

Answer 9

Dividing Binary by 2 to the power of spaces moved.

Question 10

What are Alphanumeric characters?

Answer 10

Used to make words and strings; Computers are unable to process them and-so they are represented by binary in character sets.

Question 11

ASCII:

Answer 11

7- bit binary code representing 128 different code; each character fits into 1 byte.

Question 12

Extended ASCII:

Answer 12

8-bit binary code representing up to 256 characters the first 128 being the original ASCII. Useful for European languages with unique accents.

Question 13

Unicode:

Answer 13

Covers every possible character that could be written; 16-bit and 32-bit codes. Unicode covers all major languages, suchas Greek, Russian and Chinese.

Question 14

Bitmap Images are made of _____?

Answer 14

Pixels- colours represented by binary code, the larger the range of colours the larger the bit count of a pixel.

Question 15

Number of bits per pixel is called _____.

Answer 15

colour depth

Question 16

Total number of colours = _______

Answer 16

2^ colour depth

Question 17

What is the resolution?

Answer 17

The density of pixels in an area, commonly measured in dots per inch (dpi)

Question 18

Increasing resolution or colour depth increases ______.

Answer 18

File size and image quality.

Question 19

What is Metadata?

Answer 19

Information stored to the file including the image’s file format, height, width, colour depth and resolution.

Question 20

What is an Analogue signal?

Answer 20

A continually changing piece of audible data.

Question 21

Analogue data needs to be converted into _____

Answer 21

Digital Data, does this by the process of sampling.

Question 22

How is sampling used for audio?

Answer 22

Amplitude is measured at regular intervals, only taking values dependent on bit rate. The data loses data in the sampling process, however this can be mitigated by more regularly taking samples.

Question 23

Sampling Frequency is _____

Answer 23

Samples taken per second.

Question 24

Sample size is _____

Answer 24

Bits available for each sample.

Question 25

Bit rate is _____

Answer 25

Number of Bits per second of audio.

Question 26

Equation for Bit Rate?

Answer 26

Bit Rate = Sampling frequency x Sample Size.

Question 27

Uses of compressing data?

Answer 27

Less storage space used; Quicker to stream or download; allows web pages to more quickly load and abiding data restrictions set by emails.

Question 28

Lossy Compression:

Answer 28

Pros: Greatly reduced file size. Takes up less bandwidth. Commonly used. Loss in quality usually unnoticeable.

Cons: Loses data; can’t be used on text or software files.

Question 29

Lossless Compression:

Answer 29

Pros: No reduction in quality, can be decompressed; can be used on files and text.

Cons: Only slight reduction in file size.

Question 30

what is a Character Set:

Answer 30

A collection of characters a computer recognises from their binary representation.