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RAW CS 2.6
Data Representation KO
| Term | Definition |
|---|---|
| Binary (Base 2) | 0 and 1 Computers use binary – digits 0 and 1 – to store data |
| Denary (Base 10) | 0,1,2,3,4,5,6,7,8,9 The number system most commonly used by people |
| Bit (b) | A single binary digit The smallest unit of data in computing represented by a 1 in binary |
| Nibble | 4 bits = half a Byte |
| Byte (B) | 8 bits - A group of 8 Bits is called a Byte Equal to one character on the keyboard |
| Kilobyte (KB) | 1000 Bytes A plain text email is equal to 2KB |
| Megabyte (MB) | 1000 Kilobytes Used to measure transmission speeds on the internet and storage space on CDs Three minute MP3 audio file is 3MB |
| Gigabyte (GB) | 1000 Megabytes Used for high definition videos One hour film compressed a MPEG4 is 4GB |
| Terabyte | 1000 Gigabyte Lots of secondary storage devices use terabyte 1TB = 300 hours of video |
| Petabyte (PB) | 1000 Terabytes Holds over 2000 years of songs back to back or 315 million photos |
| ASCII | Most commonly used character set in the English speaking world. Each ASCII character is given a 7-bit binary code this means it can represent a total of 128 different characters. |
| Extended ASCII | Extended ASCII is a character set which gives each character an 8-bit binary code, allowing for 256 characters. The first 128 characters are in exactly the same order as the ASCII Characters |
| Unicode | Unicode comes in several different forms and tries to cover every possible character that might be written. In its most common forms it uses 16 bit and 32 bit binary codes. |
| Conversion | Data conversion is the conversion of computer data from one format to another |
| Transistor | a transistor is a device used to amplify its electrical input. In the digital world, a transistor is a binary switch and the fundamental building block of computer circuitry. |
| Overflow Error | An error that occurs when the computer attempts to handle a number that is too large for it |
| Character Set | A group of characters that a computer recognises from their binary representation Standard character set are ASCII, Extended ASCII and Unicode |
| Pixel | One of the individual units (often called dots) that make up an image |
| Colour Depth | The amount of bits available for colours in an image. |
| Analogue | A continuous signal which can't be processed by a computer |
| Sampling Frequency | The number of audio samples that are taken per second |
| Sample rate | number of samples of audio carried per second, measured in Hz or kHz (one kHz being 1000 Hz). For example, 44100 samples per second can be expressed as either 44100 Hz, or 44.1 kHz |
| Check Digit | A digit added to a string of digits which is used to check is all the digits have been entered and read correctly |
| Modulo 10 | The modulo operation (abbreviated “mod”, or “%” in many programming languages) is the remainder when dividing. For example, “5 mod 3 = 2” which means 2 is the remainder when you divide 5 by 3. |
| Parity Bit | A bit placed at the end of binary data to show if it has been received correctly |
| Vector Graphic | An image stored as mathematical instructions for how to draw it. This means its width and height can be increased without the loss of quality |
| Bitmap Graphic | An image made up of pixels. This type of image loses quality if its width and/or height are increased. |
| Resolution (graphics) | The density of pixels in an image, often measured in dpi |
| Metadata | Data about data, eg photo image files have data about where the photo was taken and which camera took the picture. |
| Compression | A method of reducing file sizes, particularly in digital media such as photos, audio and video. |
| Bit Rate | Bit Rate is the number of bits used per second of audio - it is calculated using... Bit Rate = Sampling Frequency x Sample Size x no. of channels Increasing the sampling frequency and sample size will increase the bit rate |
| Lossy Compression | A form of compression that reduces digital file sizes by removing data. |
| Redundancy (data) | Data redundancy is a condition created within a database or data storage technology in which the same piece of data is held in two separate places. |
| Run-length encoding | Run-length encoding (RLE) a very simple form of lossless data compression runs of data are stored as a single data value and count, rather than as the original run |
| Bit Depth | The number of bits available to store an audio sample - usually 16 bits on a CD and 24 bits on a DVD |
| GIF | Graphics interchange format - an 8-bit digital image format which uses lossless compression. Also used for short animations. |
| JPEG | oint Photographic Experts Group - a digital image format which uses lossy compression. |
| Memory | The part of a computer that stores data. |
| PNG | Portable network graphics - a digital image format that uses lossless compression. |
| Resolution | The number of pixels that make up a screen vertically and horizontally - the higher the resolution of an image, the more detail it holds. In computing terms, resolution is measured in dots per inch (dpi). |
| Sampling Intervals | Gaps between each of the points where the analogue recoding is sampled E.F the audio file might be sampled every 5 milliseconds (ms) - the sampling interval would be 5ms |
| Sampling Frequency (Sample Rate) | is how many samples you take in a second - it is usually measured in kilohertz (kHz) e.g. a common sampling frequency is 44,100 samples per second (44.1 kHz) |
| Sample size | is the number of bits available for each sample (like colour depth but for sound) - |
| Lossy | There is some loss in the quality of the image when it is compressed |
| Pixel Density | The number of pixels per square inch of display |
| Rule of Binary Addition | Work right to left and apply the rules 1) 0+0 = 0 2) 0+1 = 1 3) 1+0 = 1 4) 1+1 = 0 and carry 1 5) 1+1+1 = 1 and carry 1 |
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Jennybutton
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