Unit 1 Data Representation

Computer uses binary. Has transistors which have 1s and 0s which are located in the integrated circuits.

• Memory dumps • Represent colour in HTML • MAC Addresses • URL • Assembly language • IPv6 Addresses • Locations in memory

NN-NN-NN-DD-DD-DD First part is the organisationally unique identifier (OUI) or the manufacturer ID Next is universally administered address (UAA) serial number

• Musical Instrument Digital Interface • Stores a set of notes • Does not store actual sounds • Data in file recorded using digital instruments • Sends file to audio synthesiser to play note • Specifies when each note plays and stops, duration, tempo, instrument type • Individual notes can be edited

• Joint photographic experts group • Standard format for storing lossy compression image • Maintain decent img quality • File size = pixels * primary Color’s

• Format for digital audio • Actual recording of the sound • Is a lossy compression format • Recorded using microphone

• It can store multimedia • Music, videos, text, photos • Format of lossy compression

• Method of data transmission • System could use odd or even parity • Odd/Even parity is decided and parity bit is added at the end • When receiver gets data a check is performed • Bits are counted • If incorrect data sent repeatedly till server times out Limitations: • Transposition error • When bits still add up to odd/even number • Even number of incorrect bits

• Transmitter sends data in packets • When received it is checked for errors • If no errors, sends an acknowledgment • If no acknowledgment received, it sends it repeatedly • Till server times out

• Data is input with check digit • Calculation performed on inputted data • Calculated digit is then compared to a stores value • If it matches, data entered is correct • If no match, data entered is incorrect

• Transmitter sums up total group of data before transmission • Data is sent along with the sum • Receiver works out sum and compares to stored value from transmitter • Data should match meaning it’s correct • If no match data entered is incorrect

Small - Large Bit Nibble = 4 bits Byte = 8 bits Kilobyte = 1000 bytes Megabyte = 1000 kilobytes Gigabyte = 1000 megabytes Terabyte - 1000 gigabytes

• A compression algorithm used • Data will be lost permanently • Reduce colour depth • Reduce number of pixels • Reduce sample rate • Use perceptual music shaping (removes inaudible sounds)

• Compression algorithm • No data will be removed permanently • For example an RLE algorithm may be used • Repeated patterns are identified and indexed • Sometimes replaced

• Stores position and colour of every pixel • Very detailed images used for photos • Makes them large files • If compression resolution decreased • Uses .bmp file

• Mathematically constructed image • Uses math formulas to draw shapes and lines • Results in small file size • Uses .svg file • Good for cartoons unaffected by pixelation

− Lossy decreases the file size more − Take up less storage space on webserver/users' computer − Quicker to upload/download − May not need to be high quality − Website will load faster for users − Less lag/buffering when watching − Takes up less bandwidth to download/upload − Uses less data allowance

− Image if compressed does not become pixelated − User has the option retain all original data − Can restore the compressed image into original − Also reduces file size to an extent