Data Representation

Question 1

What are the 3 Steps to create a Twos Complement Number

Answer 1

Create the positive number binary number

Invert all the 0’s to 1’s and all the 1’s to 0’s

Add 1 to the RIGHT of the number. (Sometimes called the Least Significant Bit)

Question 2

How are positive and Negative numbers stored in a computer

Answer 2

As a binary number using Two’s complement.

Question 3

What is the formula for the range of positive and negative integers which can be represented in twos complement using n bits.

Answer 3

-2^n-1 …. 2^n-1 - 1

Question 4

What is the formula for the largest integer which can be represented in twos complement using n bits.

Answer 4

2^n-1 - 1

Question 5

What is the formula for the smallest integer which can be represented in twos complement using n bits.

Answer 5

-2^n-1

Question 6

What is the formula for the range of positive and negative integers which can be represented in twos complement using 8 bits.

Answer 6

-2^n-1 …. 2^n-1 - 1
= -2^8-1 to ^8-1 - 1
= -2⁷ to 2⁷ - 1
= -128 to 128 - 1
= -128 to 127

Question 7

What is the formula for the largest integer which can be represented in twos complement using 8 bits.

Answer 7

2=^n-1 - 1
=2^8-1 - 1
=2⁷ - 1
=128 - 1
=127

Question 8

What is the formula for the smallest integer which can be represented in twos complement using 8 bits.

Answer 8

-2^n-1
= -2^8-1
= -2⁷
= -128
**= -128 **

Question 9

How does increasing the number of bits to store the mantissa impact the number stored.

Answer 9

Increasing the number of bits used to store the mantissa:
increases the precision of the number.

decreases the number of bits available for the mantissa, and so the precision of the number is decreased.

Question 10

How does increasing the number of bits to store the exponent impact the number stored.

Answer 10

Increasing the number of bits used to store the exponent:
increases the range of the number.

Question 11

How does decreasing the number of bits to store the mantissa impact the number stored.

Answer 11

Decreasing the number of bits available for the mantissa will make precision of the number is decrease

Question 12

How does increasing the number of bits to store the exponent impact the number stored.

Answer 12

precision of the range of numbers represented will decreased.

Question 13

What impact will adding 1 extra bit to the exponent have on the range of numbers which can be stored

Answer 13

The range of numbers represented will double

Question 14

What impact will removing a 1 bit from the exponent have on the range of numbers which can be stored

Answer 14

The range of numbers represented will half

Question 15

Extended ASCII - How many bits does extended ASCII use to represent a character and how many characters can it represent?

Answer 15

uses 8 bits to represent a character
can represent 256 different characters

Question 16

Extended Unicode - How many bits does extended Unicode use to represent a character and how many characters can it represent?

Answer 16

Unicode uses 16 bits to represent a character
can represent 65,536 characters

Question 17

State one advantage of Unicode over ASCII

Answer 17

Unicode has more bits therefore can be used to represent characters from many different languages (Arabic, Japanese, Latin etc) and emojis

Question 18

State one disadvantage of Unicode over ASCII

Answer 18

Unicode uses 2 bytes (16 bits) to represent a character where ASCII only uses one byte (8 bits) therefore more

Question 19

State 2 advantages of bitmap images

Answer 19

can produce realistic photographic images
control over pixel-level editing

Question 20

State 2 disadvantages of bitmap images

Answer 20

resolution is set at point of creation and cannot be increased without a loss of quality (resolution dependent)
tends to have a larger file size than a vector graphics file
can be time consuming to edit

Question 21

State 2 disadvantages of vector graphic images

Answer 21

Disadvantages
no control over pixel-level editing
unsuitable for photo-realistic images

Question 22

State 2 advantages of vector graphic images

Answer 22

can be scaled without a loss in quality (resolution independent)
vector objects can be edited independently of each other
vector objects can be easily moved / manipulated
tends to have a smaller file size than a bit-mapped graphics file

Question 23

Describe the use of keys in encryption

Answer 23

Uses a pair of keys.
A public key is known by everyone and is used to encrypt data.
A private key is known only to the recipient and is used to decrypt data.

Question 24

Describe Asymmetric Encryption

Answer 24

Asymmetric Encryption uses a pair of keys.
A public key is known by everyone and is used to encrypt data.
A private key is known only to the recipient and is used to decrypt data.

Question 25

Describe the use Digital certificates

Answer 25

Digital certificates Issued only by trusted entities. Authenticates a person, allowing them to exchange data over the Internet using a public key. They ensures that the communication between is kept secure and can only be understood by the intended sender and receiver.

Question 26

Describe the use Digital Signature

Answer 26

Digital Signature Type of e-signature that uses encryption and when bound to a document it: ● authenticates or guarantees the sender of the document is legitimate; ● guarantees that the document has not been altered.