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27 Cards in this Set
- Front
- Back
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Binary number system |
base 2 numbers, only consists of 2 numbers (0,1) |
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digital signal |
an electrical signal that is converted into a pattern of bits, it has a descrete value at each sampling point |
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bit |
a binary digit either a 0/1 |
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byte |
8 bits |
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binary to hex |
eg. 01011010 - sperate into two 0101/1010 - work out hex 0101=5 1010=10/A hex = 5A |
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hex to denary |
- split into two B/6 - left side *16 - right side *1 B=11 11*16=176 176 + 6 = 182 |
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overflow error |
an overflow error occurs when the answer of a binary sum is greater than the number of bits in the answer eg. >8 bits |
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binary shift |
- left shift *2 - right shift ÷2 |
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check digit |
a digit added to a string of numbers for error detection purposes |
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parity bit |
a bit added to binary numbers to detect an error when data is transmitted |
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character |
A character is a single letter/number/symbol used for making strings |
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character set |
collections of characters that a computer recognises from their binary representation |
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character set examples |
ASCII (7bit/128char) EXTENDED_ASCII(8bit256char) Unicode (16/32bit>1000char) |
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pixel |
a picture element, the smallest part of a computer image |
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bitmap |
the most common type of image, the colour of each pixel is represented by a binary code |
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colour depth |
the number of bits used for each pixel total colours= 2ⁿ n=bits per pixel |
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resolution |
the density of pixels in that image, measured in dpi/dots per inch, the greater the resolution the better the quality but the bigger the file |
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metadata |
extra information stored in an image file, includes; files format/height/width/colour depth/resolution without it the computer wouldn't be able to make sense of the data |
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Sound |
sound is recorded by a microphone as an analogue signal which are pieces of continually changing data |
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analogue signals |
they need to be converted into digital data so that computers can read and store it. this is fone by an ADC (analogue to digital converter) |
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sampling |
converting analogue to digital signals it is done by sampling the amplitude of the wave at regular intervals, amplitude varies depending on bit depth |
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sampling terms |
sampling intervals: gaps between each sampling point sampling frequency: how many samples taken per second (Hz/KHz) sample size: the number of bits available for each sample |
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Bit rate |
The number of bits used per second of audio bit rate = sampling frequency * sample size |
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Lossy compression |
compresses data by permanently removing data from the file used for music/photos/video/medical images/scanned documents |
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lossless compression |
makes the file smaller by temporarily removing data to store it and restoring it to its original state when opened used for databases/emails/spreadsheets/office docs |
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uses of compression |
- smaller files take up less storage space - streaming and downloading files is quicker and takes less bandwidth - allows web pages to load quicker - email often puts restrictions on file sizes |
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compression file types |
- JPG - PNG - BMP - GIF |
