section 7 data representation Flashcards
what are logic gates
are special circuits built into computer chips
they receive binary data, apply a Boolean operation, then output a binary result
What does a Not gate do
takes a single input and gives a single output
the output is always the opposite
what does a And gate do
takes two inputs and gives one output
if both inputs are 1 the output is 1 otherwise the output is 0
what does a OR gate do
takes two inputs and gives one output
if one or more inputs are 1 then the output is 1 otherwise the output is 0
units in size order
bit (1 or 0) nibble(4 bits) byte (8 bits) kilobyte (1000 bytes) megabyte (1000 kilobytes) gigabyte (1000 megabytes) terabyte (1000 gigabytes) petabyte (1000 terabytes)
what are check digits/parity bits
are a way of checking that data has been entered and read correctly
they are digits added to the end of numbers and are calculated using the other digits in the number.
what happens if one bit of the binary string is read incorrectly
it will be fixed with either a even parity check or odd parity check
what is a binary shift
moves every bit in a binary number left or right a certain number of places
Gaps at the beginning or end of the number are filled in with 0
what does left shift do
multiply a binary number
for every place shifted the number is doubled
what does right shift do
divide a binary number
for every place shifted the number is halved
what is a hexadecimal number
base 16
advantages of using hex rather than binary
simpler to remember
shorter so less chance of error
easier to convert between hex and binary
list the hex numbers up to 15 in denary
0 1 2 3 4 5 6 7 8 9 A B C D E F
what are character sets
are collections of characters that a computer recognizes from their binary representation
how does the character set translate the binary code to the computer
when you press a button on the key board it sends a binary signal to the computer telling it which button you pressed.
It then uses the character set to translate the binary code into a character
what is ASCII and how many characters does it contain
most commonly used character set
its given a 7-bit binary code so can represent 128 characters
whats nice about ASCII
an extra bit is added so that it fits nicely into 1 byte
whats the difference between Extended ASCII and ASCII
Extended has a 8-bit binary code so 256 characters are represented
what is Unicode and why is it the best
covers every single possible character
uses 16-bit and 32-bit binary code
covers all major languages
what are bitmap images made of
pixles
how can you get a greater range of shades
increasing the number of bits for each pixle
total number of colours =
2 to the power of n (n = number of bits)
what is the colour depth
the number of bits used for each pixel
what is resolution
the density of pixels per image
measured in dots per inch
