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
