SET 2

Question 1

Explain signed bit and it’s problems

Answer 1

The most significant bit is set to 1 for negative and 0 for positive
-problems: two values for 0, discontinuity in numbers

Question 2

Give two advantages of using two compliment

Answer 2

• One value for 0

- continuity of numbers

Question 3

How to store decimal numbers

Answer 3

Using floating point with the mantisa and exponent

Question 4

In floating point notation what determine the accuracy of the number

Answer 4

Number of bits allocated to the mantissa

Question 5

Describe how BMS images are stored

Answer 5

• As a grid of pixels each pixel has a binary representation in memory
• Whole screen stored
• number of bits for each pixel determines the range of colours available

Question 6

Describe how vector images are stored

Answer 6

As objects and their attributes

E.g rectangle (start X,Y, length,breadth, line, fill)

Question 7

The advantages of Vector over BM graphics

Answer 7

• Can layer objects
• Can scale up without loss of resolution
• Can edit individual attributes is easily

Question 8

The advantages of BM over vector graphics

Answer 8

• Can edit at pixel level

- More realistic, for photographs

Question 9

Add a circle to an image describe effect on file size of both BM and vector images

Answer 9

• Vector file size will increase as additional object stored

- BM no change to file size as stores whole screen with no layering

Question 10

Give advantages and disadvantages of floating point notation

Answer 10

Advantage: can Store very large and very small numbers
Disadvantage: Accuracy may be reduced depending on the number of bits available

Question 11

What determines the range of real numbers

Answer 11

Number of bits allocated to exponent

Question 12

Explain bit depth

Answer 12

• Number of bits used to store each pixel

- determines the range of colours

Question 13

If you increase the bit depth of a photo after it was taken, why is there no improvement

Answer 13

Picture will only have colours that were available need to do it before taking photo

Question 14

Describe two effects of reducing the bit depth of an image

Answer 14

Reduces file size

reduces range of colours available

Question 15

Explain resolution

Answer 15

Number of pixels making up an image measured in DPI

Question 16

What do the first 32 to ASCII codes represent

Answer 16

Control characters ( non-printable) E.g escape

Question 17

Why do computers use binary

Answer 17

• Only 4 arithmetic rules so Simple calculations

- Only two values so robust

Question 18

What is a parity bit

Answer 18

• A parity bit or check bit is the simplest form of error detection
• A bit added to the end of binary code that indicates whether the number of 1s in the binary number is even or odd

Question 19

Name five types of computers

Answer 19

Laptop tablet smartphone desktop mainframe

Question 20

State three criteria to consider when buying a laptop

Answer 20

• RAM capacity ( 3 GB or more) -Processor speed ( 3 GHz or faster)
• Hard disc capacity ( 300 GB or more)

Question 21

Give advantages of a touch screen as an input device

Answer 21

• Don’t need any extra hardware such as keyboard
• Touch screens work well with icon driven systems
• Little data to enter so easily and less chance of error

Question 22

Give disadvantages of a touch screen as an input device

Answer 22

• Users must be able to accurately select targets on touchscreens, and avoid accidental selection of adjacent targets
• Not suitable for entering large amounts of data
• Not robust: can break easily if dropped
• More expensive than alternatives such as mouse or keyboard

Question 23

Why is it important that hardware is scalable

Answer 23

If a company expands then they need to be able to cope with sudden increase in number of users

Question 24

Name three software consideration

Answer 24

1. Open source vs proprietary source
2. licensing
3. portability

Question 25

What is proprietary software

Answer 25

• Proprietary source code is usually a secret and not available to users
• Proprietary software requires the user to pay for a licence fee