Chapter 4 - Data representation

Question 1

Character set

Answer 1

The list of codes and matching characters for a computer

Question 2

Metadata

Answer 2

Data about data e.g. date made

Question 3

Pixel

Answer 3

One dot in an image

Question 4

Colour depth

Answer 4

Bits per pixel which decides how many colours each pixel could represent

Question 5

Resolution

Answer 5

Number of pixels per unit

Question 6

Sample interval

Answer 6

The time between samples taken of an audio file to convert it from analogue to digital

Question 7

Bit rate

Answer 7

The amount of space needed for each sample

Question 8

Operator (opcode)

Answer 8

Instruction part of binary code - bit pattern is unique in computer instruction set

Question 9

Operand

Answer 9

Data part of binary code

Question 10

Accumulator

Answer 10

Special register in the CPU used to store the results of any calculation

Question 11

What is the order of units for data?

Answer 11

Bits, bytes, kilobytes, megabytes, gigabytes, terabytes

Question 12

What is an overflow error?

Answer 12

When the result of an addition is too big to fit into the space given and an extra digit is needed - computers can’t handle this

Question 13

Why is hex often used? (3)

Answer 13

1) Easy to convert to/from binary
2) Easy to work with
3) Saves space - uses fewer digits

Question 14

How many colours can 8 bits per pixel represent?

Answer 14

2^8 = 256

Question 15

How many bits per pixel is high colour and true colour?

Answer 15

16bbp - high

24bbp - true

Question 16

What happens when sound is sampled at a low rate?

Answer 16

Few samples taken, poor match to original, smaller file

Question 17

What does a high bit rate mean?

Answer 17

More accurate + quality, larger file

Question 18

How does a computer tell the difference between instructions and data?

Answer 18

It doesn’t - it deals with data according to what it expects to find

Question 19

How many bits do ASCII and Unicode use?

Answer 19

ASCII - 7 or 8

Unicode - 16