Representation of data Flashcards
What is the order of unit?
bit -> nibble -> Byte -> Kilobyte -> Megabyte -> Gigabyte -> Terabyte -> Petabyte
What size stores one character for ASCII ?
A byte
What size stores most files (e.g. songs, pictures or word docs?)
Kilobytes and Megabytes
What size stores HD videos and applications?
Gigabyte
What size is secondary storage capacity?
Gigabyte and Terabyte
What is A in denary?
10
What is an overflow error?
when the number of bits is more than 8
Why is Hexadecimal used?
it is used to simplify binary and its also harder to make a mistake when writing
What is a character set?
a defined list of characters recognised by the computer hardware and software. it includes uppercase, lowercase, digits and symbols
they allow computers to convert the characters into binary code
What is ASCII?
- a commonly used character set for english speakers
- character=7-bit code
- total of 128 characters
- extra 0 to make it fit 1 byte
What is extended ASCII?
- used for european languages
- character=8-bit code
- total of 256 characters
What is Unicode?
- covers every posiible character
- 16-bit or 32-bit codes
- includes languages that use a different alphabet e.g. russia, japan and greece
What is a pixel?
a picture element is a tiny coloured square that represents one colour and is stored as a binary value
What is image resolution?
the concentration of pixels within an area measured in dots per inch
If there are 3 bits how many colours are displayed?
8 colours
How do you find out the colour depth?
xbits = 2 to the power of x colours
What is metadata?
it provides additional information for example file format, width and height. it is needed as it makes it easier to locate files and tells the device how to display the data
What are the dimensions?
the height and width of an image
What happens to the file size as you increase the resolution?
increases the number of pixels which increases the number of bits which increases the file size
What happens to the file size as you increase the colour depth?
increases the number of bits and therefore the filesize
What are the primary colours?
red, blue and green
How is each pixel represented?
as 3 denary numbers between 0 and 255.
the colour is named in Hex #RRGGBB
What is lossy compression?
- removed data to reduce filesize, the file cant be restored to its original size.
- bands of similar colours are bought together to reduce the number of colours
What is lossless compression?
- shrinks the file size but keeps the quality
- collect groups of the same colour instead of storing the individually
What is sound sampling?
the amplitude of the wave is continuosly measured and stored as a binary value
What are some audio file formats?
MP3, WAV and Ogg
How is sound quality effected?
- sample resolution (number of bits used
- sample interval (time between each sample)
- sample frequency (number of samples per second)
- bit rate (not of bits used per second)
What is an instruction?
a binary sequence which carries an action that it understands
What is assembly code?
short text commands instead of binary
How are data and instructions distinguished?
they are stored in different parts of the memory
What are some image file formats?
- BMP
- JPG
- GIF
- PNG
What is a bitmap image?
a graphic composed of a grid of pixels which are different colours.
large file size
How much storage is used to store one unicode digit?
16
Why is binary used to represent data in a computer?
Circuit only needs to check for two states/uses switches electricity flowing or not flowing/on or off/1 and 0 resulting in more reliable circuits.
What is PDF
file used to store documents
What is HTML?
used to define content/ layout of a web page
What is a ZIP file?
compressed data
Why are files compressed?
- It reduces the size of the file which needs to be
transmitted which shortens download time and also reduces Internet traffic - allows multimedia files to be streamed
When is lossy compression used?
music files(mp3), large resolution images for displaying on small screens.
When is lossless compression used?
text files
