# Data Representation

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- Created by: 12johnsonamie
- Created on: 10-10-16 09:24

What is meant by a binary digit?

Either of the digits 0 or 1 used in the binary number system. It is shortened to the term ‘bit’.

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What is meant by the term byte?

A unit that usually consist of 8 bits. A byte is the number of bits needed to encode a single character of text and is the smallest addressable unit of memory.

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Explain what is meant by a ‘nibble’ and why it is used in computing.

A nibble consists of 4 bits or half a byte. As there are possible values, so a nibble corresponds to a single hexadecimal digit. Therefore an eight digit byte can be represented by two digits of hexadecimal.

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How do you change binary into hexadecimal?

First of all you change the binary into nibbles (4 digit binary) and translate each 4 digit part into one letter or number. (E.G. 1010 = A as A is equal to 10).

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How many hexadecimal numbers/letters are there?

15, all numbers above 9 are letters starting with A.

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State all data sizes in order from smallest to largest.

Bit, Nibble, Byte, Kilobyte, Megabyte, Gigabyte, Terabyte.

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A computer contains data and instructions in binary. Explain why computers use binary.

So that computers can be based on logic circuits. … ( each part of the circuit) can be in one of two states … 0 and 1/true or false

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How much is 2 Terabytes in Gigabytes?

1024 x 2 = 2048

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How many Kilobytes are in a Megabyte?

1024

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What is an analogue device?

Analog device is usually a combination of both analog machine and analog media that can together measure, record, reproduce, or broadcast continuous information e.g. a clock.

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What is a digital device?

A digital device is an electronic device which uses discrete, numerable data and processes for all its operations.

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Explain why data needs to be converted into a binary format in order to be processed by computers.

Computers are digital and do not measure the size of the voltage – only IF there is or isn’t a voltage value. Therefore there are only two states – on and off or true and false.

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How much does binary go up per digit?

x2, the digit before is multiplied by 2.

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What are the rules for adding binary?

0+0=0 1+0=1 1+1=10 1+1+1=11

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Explain what is meant by an overflow error or overflow condition.

Every computer has a well-defined range of values that it can represent. If during execution of a program it arrives at a number outside this range, it will experience an overflow error.

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Why is hexadecimal used in computing?

The main reason that hexadecimal numbers are used is because it is much easier to express binary number representations in hex than it is in any other base number system.

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Explain why hexadecimal numbers are often used to represent binary numbers.

Hex numbers are shorter/more memorable than equivalent binary numbers.

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Explain what is meant by a ‘character set’.

A defined list of characters recognised by the computer hardware and software. Each character is represented by a number.

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ASCII is an acronym. In the space below state what words the initial letters represent.

American Standard Code Information Interchange

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The first edition of the ASCII code was published in 1963 and it was based on an earlier code. What was this earlier code used for?

Teletype and teleprinter machines.

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How many bits are used for this code?

7 bits

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How many characters can be represented using 8 bits?

256

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Why was the UNICODE character set developed?

A universal standard character set that covers all writing systems. There needed to be more characters to cover all the languages on earth.

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Pixels are the smallest individual element in an image. Pixel is a combination of which two words?

Picture and element.

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Pixels hold information on the levels of which three colours?

Red, green and blue.

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What is the difference between the terms ‘dimensions’ and ‘resolution’ when applied to digital images?

‘Dimensions’ refers to the total number of pixels along an image’s width and height e.g.640 x 480. ‘Resolution’ refers to the density of pixels in an image – the greater the density, the greater the image sharpness and clarity.

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What does lossless mean?

(of data compression) without loss of information. E.g. RAW

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What does lossy mean ?

(of data compression) in which unnecessary information is discarded. E.g. JPEG

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What is data compression?

In signal processing, data compression, source coding, or bit-rate reduction involves encoding information using fewer bits than the original representation.

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What is metadata?

a set of data that describes and gives information about other data.

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## Other cards in this set

### Card 2

#### Front

What is meant by the term byte?

#### Back

A unit that usually consist of 8 bits. A byte is the number of bits needed to encode a single character of text and is the smallest addressable unit of memory.

### Card 3

#### Front

Explain what is meant by a ‘nibble’ and why it is used in computing.

#### Back

### Card 4

#### Front

How do you change binary into hexadecimal?

#### Back

### Card 5

#### Front

How many hexadecimal numbers/letters are there?

#### Back

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