Paper 2 Data representation

Question 1

State the number of bits there are in: 1 nibble

Answer 1

4 bits

Question 2

State the number of bits there are in: 1 byte

Answer 2

8 bits

Question 3

Work out the binary representation for 134.

Answer 3

(134)10 = (10000110)2

Question 4

Showing your working, add the binary numbers 00111111 and 01001100. Convert the final answer into denary.

Answer 4

63 + 76 = 139 in binary 10001011

Question 5

Add the numbers 249 and 11 using binary addition, storing your answer in 8 bits.

Answer 5

1 00000100

Question 6

Convert the denary number 167 into hexadecimal, showing all of your working.

Answer 6

A7

Question 7

Convert the hexadecimal number D3 into denary, showing all of your working.

Answer 7

211

Question 8

Identify the process of adding a value at the end of the sequence to ensure an input sequence by a user is correct.

Answer 8

Checksum or a parity bit is at the end of a sequence for ensuring the input sequence is correct.

Question 9

Name the character encoding standard that enables up to 128 different commonly used characters

Answer 9

ASCII

Question 10

What are the l

imitations of the ASCII character set.

Answer 10

The 128 or 256 character limits of ASCII and Extended ASCII limits the number of character sets that can be held. Representing the character sets for several different language structures is not possible in ASCII, there are just not enough available characters

Question 11

Name the term given to a single or smallest element on an image.

Answer 11

A pixel is the smallest single component of a digital image.

Question 12

Name the number system often used to represent red, green and blue values in a picture.

Answer 12

Hex can be used to represent colours on web pages and image-editing programs using the format #RRGGBB (RR = reds, GG = greens, BB = blues). The # symbol indicates that the number has been written in hex format.

Question 13

What do we mean by the term ‘Sample Rate’?

Answer 13

The sample rate is how many samples, or measurements, of the sound are taken each second. The more samples that are taken, the more detail about where the waves rise and fall is recorded and the higher the quality of the audio. Also, the shape of the sound wave is captured more accurately.

Question 14

Give reasons for using compression on a computer.

Answer 14

File compression reduces the amount of space needed to store data. Using compressed files can free up valuable space on a hard drive, or a web server.

Question 15

Why is lossy compression is preferable to lossless compression when compressing an image file?

Answer 15

The advantage of lossy methods over lossless methods is that in some cases a lossy method can produce a much smaller compressed file than any lossless method, while still meeting the requirements of the application. Lossy methods are most often used for compressing sound, images, or videos.