Data Representation

Question 1

What is a Real Number

Answer 1

A number with a whole part and a fractional part e.g. 17.0, 3.3333

Question 2

What is the radix point in binary

Answer 2

The name of the point (.)

Question 3

What are the four parts of floating point representation

Answer 3

Sign, Mantissa, Base and Exponent

Question 4

What is the Mantissa

Answer 4

The significant digits of the number being represented

Question 5

What is the Exponent

Answer 5

Scales the number by shifting the position of the floating radix point

Question 6

What is Single Precision floating point

Answer 6

When you represent floating point negative numbers of certain size and range by describing the order the information comes in

Question 7

What are key features of Single Precision floating point

Answer 7

Occupies 32 bits in computer memory, Exponent is 8 bits, mantissa is 23 bits and the sign is 1, bias number is 127

Question 8

When would Single Precision floating point be used

Answer 8

Wide representation, simple programs like games

Question 9

Why is Single Precision floating point used

Answer 9

Less expensive, fewer resources needed

Question 10

What are key features of Double Precision floating point

Answer 10

Occupies 64 bits in computer memory, Exponent is 11 bits, mantissa is 52 bits and sign is one bit, the bias number is 1023

Question 11

When would Double Precision floating point be used

Answer 11

Used for minimization of approximation, used in complex programs like scientific calculators

Question 12

Why isn’t Double Precision floating point used for every computation

Answer 12

The cost incurred using this format does not always justify its use, it provides more accurate results but at the cost of greater computational power, memory space and data transfer

Question 13

What would be the simplest idea to represent text

Answer 13

Binary bit pattern per character

Question 14

What are key features of ASCII

Answer 14

7 bits providing 128 unique characters

Question 15

What are key features of Unicode

Answer 15

16 bits used normally (sometimes 8 or 32 bits) providing 65536 different characters

Question 16

What are the ways to represent negative numbers

Answer 16

Sign-Magnitude or Two’s Complement

Question 17

What is an Integer Overflow

Answer 17

When an arithmetic operation attempts to create a numeric value that is outside of the range that can be represented with the given bits

Question 18

What happens when there is an integer overflow

Answer 18

The least significant representable bits of the results are stored, the result is said to wrap around the maximum

Question 19

What is one way we can represent colors

Answer 19

RGB

Question 20

Define Colour Depth

Answer 20

The number of bits used to encode color

Question 21

Define Pixels

Answer 21

Dots of colour in the image

Question 22

Define Resolution

Answer 22

Numbers of pixels in the image

Question 23

What is Raster Graphics

Answer 23

Treats the image as a collection of pixels

Question 24

What are examples of Raster Graphics

Answer 24

BMP,GIF,PNG,JPEG

Question 25

Define Vector Graphics

Answer 25

Treats the image as a collection of mathematically defined geometric objects in the image

Question 26

What is an example of Vector Graphics

Answer 26

SVG

Question 27

What does JPEG stand for

Answer 27

Joint Photographic Experts Group

Question 28

Why would SVG be good

Answer 28

The circles are mathematically defined, we can make them larger/smaller and pixilation does not occur

Question 29

What are 4 ways sound can be represented

Answer 29

AM Radio(11kHz), CD quality (44kHz), DVD quality (48kHz), Blu-ray quality (96kHz)

Question 30

Define Data Compression

Answer 30

Reduction in the amount of space needed to store a piece of data or the bandwidth to transmit it

Question 31

Define Compression ratio

Answer 31

The size of the compressed data divided by the size of the original data

Question 32

Define Lossless

Answer 32

The data can be retrieved without any loss of original information

Question 33

Define Lossy

Answer 33

Some information may be lost in the process of compression

Question 34

Define Run-Length Encoding

Answer 34

Replace the repeated sequence with a character and number of times repeated

Question 35

When would Run-Length Encoding be used

Answer 35

Would be used with binary values, not often used for natural text

Question 36

Define Keyword Encoding

Answer 36

Common patterns and single characters would be replaced with a single character

Question 37

What would you need to perform Keyword Encoding

Answer 37

Mapping table to encode and decode the information

Question 38

Define Variable Length Bit String Encoding

Answer 38

Changing the number of bits used to represent a value, making more frequent values use fewer bits than uncommon ones