4. Data Representation Flashcards Preview

GCSE - Computing > 4. Data Representation > Flashcards

Flashcards in 4. Data Representation Deck (60)
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1

How does binary work?

Each digit is a 0 or 1. The system works in base 2. That means each digit from right to left represents 1, 2, 4, 8, etc.

2

What is hex short for?

Hexadecimal

3

How many digits are there in hex?

16

0 - 9 and A - F

4

How is hex linked to binary?

Each hex digit is equivalent to a binary nibble of 4 digits. For example, 1110 is E.

5

How can an 8-bit binary number be written in hex?

Each of the two nibbles is converted to hex and then these are joined together.

For example, 1101 is D and 0100 is 4.
So, 11010100 is D4 in hex.

6

How do you convert from hex to denary?

1. Convert each digit to a nibble of binary
2. Put the two nibbles together
3. Convert this to denary

7

How do you add two binary numbers?

Using column addition.
0 and a 0 make 0.
0 and 1 make 1.
1 and 1 make 0 but carry 1 to the next column.

8

What is an overflow error?

When the processor does not have enough bytes available to process an instruction.

9

What is a nibble?

4 bits

10

What is a byte?

8 bits

11

What is a kilobyte?

1024 bytes

12

What is a megabyte?

1024 kilobytes

13

What is a gigabyte?

1024 megabytes

14

What is a terrabyte?

1024 gigabytes

15

What is the order of 'bytes' in increasing size?

Nibble
Byte
Kilobyte
Megabyte
Gigabyte
Terrabyte

16

What is a bitmap image?

An image stored as a series of values per pixel. The colour of each pixel is stored in a file.

17

What is a pixel?

A picture element - the smallest part of a bitmap picture.

18

What does DPI stand for?

Dots per inch

19

What is resolution?

The amount of pixels in an image. Usually measured in DPI.

20

How is binary used in a black and white bitmap picture?

Each pixel is represented by a 0 or 1. Only two are needed because there is only black and white.

21

What is colour depth?

The amount of bits used per pixel to encode the colour information.

22

How is binary used to represent pixels in a colourful image?

Each colour is given a binary number. If there are only 4 colours then they can be represented using 00, 01, 10 and 11.

23

What is the difference between vector and bitmap images?

BITMAP
• Each pixel is mapped and given a colour
• Suitable for photographs
• Quality is lost when stretched or resized
VECTOR
• Instruction for how to draw the picture are included
• Length of line, angles, curves, thickness of lines, etc.
• Best for cartoons and clip art
• Quality not lost when resized

24

What is lossless compression?

When a file is compressed so that picture quality remains the same and it can be decompressed into its original quality.

25

What is lossy compression?

When a file is compressed so that it permanently removed data. It cannot be decompressed into a file of the same quality.

26

What does analogue mean?

A continuously varying signal - like a car speedometer

27

What does digital mean?

A discrete value (a single number)
0s and 1s in computers

28

What does ADC stand for?

Analogue to Digital Converter

29

What is the sample rate?

The number of samples taken per second.

30

What is sample resolution?

The number of bits allocated per sample.