Coding Systems 1 - AQA A Level Computer Science

How many different combinations of bit patterns can be represented using ASCII?

• 127

• 128

• 255

• 256

The ASCII value for the letter 'a' in binary is 110 0001. What is the binary ASCII value for the letter 'e'?

• 110 0010

• 110 0100

• 110 0101

• 110 0110

The bit pattern 0110001 is sent with an even parity bit in the MSB position.

Which of these is the bit pattern receivedt?

• 00110001

• 10110001

• 01100011

• 01100010

Data is received that had been sent using majority voting. The received bit pattern is 100 000 011 111.

What bit pattern does the receiving device interpret this as?

• 0011

• 1010

• 0001

• 1001

The image shows how a modulo 11 check digit can be calculated.

Find the check digit for the string of digits 1 2 3 4 using modulo 11.

• 1

• 2

• 3

• 4

• 5

The bitmap image of the lemming is 6 pixels by 10 pixels. There are 16 available colours for each pixel. Calculate the file size of the image (not including any metadata) in bytes.

• 30

• 120

• 22.5

• 60

Which of these are advantages of vector graphics over bitmap graphics?

• Can be rescaled without distortion

• (Usually) a smaller file size

• Ideal for photographic images

• Each pixel can be modified individually

An image of a circle is to be stored as a vector graphic.

Which of these properties must be stored?

• Location of the circle (e.g. its centre)

• Radius or diameter of the circle

• The fill colour

• The colour and thickness off its outline

• The numbers of bits used to represent its colour

Bitmap files have larger file sizes than that calculated by resolution and colour depth. What is the reason for this?

• Extra bits per pixel are stored in case more colours are required

• To allow accurate rescaling of the image

• Lossless compression

• Metadata

Why was Unicode introduced to represent characters in binary?

• ASCII doesn't allow enough combinations to represent characters from other languages

• Universal international coding system required due to world wide use of digital communication

• To decrease the storage requirements of text files

• Resolve confusion between upper and lower case characters