Key Terms

Mind Map by jramsden09, updated more than 1 year ago
Created by jramsden09 about 7 years ago


Data Representation Mind Map on Key Terms, created by jramsden09 on 06/07/2013.

Resource summary

Key Terms
1 Units
1.1 Bit - A single binary digit: 1 or 0
1.2 Byte - 8 Bits
1.3 Nibble - 4 Bits
1.4 Kilobyte - 1024 bytes
1.5 Megabyte - 1024 Kilobytes
1.6 Gigabyte - 1024 Megabytes
1.7 Terabyte - 1024 Gigabytes
2 Numbers
2.1 Binary - Base 2 number system, used by computers, uses the digits 1 & 0 only.
2.2 Denary - Base 10 number system, how we normally count, uses digits 0 to 9.
2.3 Hexadecimal (Hex) - Base 16 number system used by humans to represent groups of four bits at a time. Uses digits 0 to F.
2.4 Overflow - When the result of a numeric calculation is too large to be stored in the space reserved for that type of data.
3 Characters
3.1 Character set - The set of symbols that can be represented by a computer. The symbols are called characters and can be letters, digits, space, punctuation marks and some control characters such as “escape”. Each character is represented by a numerical code that is stored as a binary integer.
3.2 ASCII - American Standard Code for Information Interchange: a 7-bit character set used by PCs. (There is also an extended ASCII character set that uses 8 bits.)
3.3 EBCDIC - Extended Binary Coded Decimal Interchange Code: an 8-bit character set used by older mainframes.
3.4 Unicode - A 16-bit character set that allows many more characters to be coded.
4 Images
4.1 Bitmap image - An image that has been stored as a series of values per pixel. The colour of each individual pixel is stored in a file.
4.2 Vector Graphic - An image file that is made up of lines and shapes that have certain properties, for example, a line may have the following properties: start- point, end-point, line colour, line thickness, line style. The properties of each shape are stored in a file to make up the image.
4.3 Pixel - Short for picture element. It is the smallest component of a bit-mapped image.
4.4 Colour depth - The number of bits used to represent the colour of a single pixel in a bitmapped image. Higher colour depth gives a broader range of distinct colours. For example, an image stored as a .gif file uses 8 bits per pixel so the image could use 256 different colours.
4.5 Resolution - The number of pixels in an image expressed as: the-number-of-pixels-across x the-number-of-pixels-down eg: 400 x 600.
4.6 Metadeta - Data about data. In the case of image files metadata is the data the computer needs to interpret the image data in the file, for example: resolution, colour depth and image dimensions.
5 Sound
5.1 Analogue - A continuously changing wave such as natural sound.
5.2 Digital - Data that is made up of separate values. How data is stored on a computer.
5.3 Sample rate - The number of times per second that the sound wave is measured. The higher the rate the more accurately the sound wave is represented.
5.4 Sample interval - The time gap between measurements of the sound wave being taken. Another way of expressing the sampling rate.
5.5 Sample resolution - The number of bits used to store the value of each sample. The higher the number of bits the more accurately the value is stored.
5.6 ADC - Analogue to Digital converter: takes real-world analogue data and converts it to a binary representation that can be stored on a computer.
6 Data and information
6.1 Data - Facts and figures with no context or format to give them meaning.
6.2 Information - Processed data that has context and format so that it conveys meaning.
7 Instructions
7.1 Instruction set - The group of instructions available for that specific processor to use. The number of instructions available will depend on the number of bits used. For example, with 4 bits there could potentially be 15 different instructions.
7.2 OP Code - The group of bits in an instruction that represents the operation such as EAT, MOVE or TURN
7.3 Compiler - A piece of systems software that converts a program written in a high level programming language into machine code (binary).
7.4 Machine code - A binary representation of a program.
7.5 High Level Programming Language - A programming language written in constructs using language we can understand. Languages include Delphi, Visual Basic, Java and C++.
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