Unit 1 Data Representation Flashcards
Binary systems
Computer uses binary. Has transistors which have 1s and 0s which are located in the integrated circuits.
Hexadecimal uses
- Memory dumps
- Represent colour in HTML
- MAC Addresses
- URL
- Assembly language
- IPv6 Addresses
- Locations in memory
MAC Address structure composed of
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
Describe MIDI File
- 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
Describe JPEG
- Joint photographic experts group
- Standard format for storing lossy compression image
- Maintain decent img quality
- File size = pixels * primary Color’s
Describe MP3
- Format for digital audio
- Actual recording of the sound
- Is a lossy compression format
- Recorded using microphone
Describe MP4
- It can store multimedia
- Music, videos, text, photos
- Format of lossy compression
Describe Parity Check and its limitations
- 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
Describe ARQ
- 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
Describe check digit
- 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
Describe check sum
- 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
Memory ascending order
Small - Large
Bit Nibble = 4 bits Byte = 8 bits Kilobyte = 1000 bytes Megabyte = 1000 kilobytes Gigabyte = 1000 megabytes Terabyte - 1000 gigabytes
Describe Lossy compression
- 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)
Describe Lossless compression
- Compression algorithm
- No data will be removed permanently
- For example an RLE algorithm may be used
- Repeated patterns are identified and indexed
- Sometimes replaced
Describe Bitmap img
- Stores position and colour of every pixel
- Very detailed images used for photos
- Makes them large files
- If compression resolution decreased
- Uses .bmp file
Describe Vector img
- 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
Why is Lossy better than Lossless
− 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
Why is Lossless better than Lossy
− 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
