Studied by 2 people
What is binary?
a base 2 number system
only two possible values - 0 and 1
What is hexadecimal?
a base 16 number system
16 possible values - 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F
used as short hand to binary because it uses fewer characters to write the same values, making it less prone to errors when reading or writing it - easier to understand
used in MAC addresses and for representing colour values
What are overflow errors?
occurs when a binary value is too large to be stored in the bits available.
What are binary shifts?
used to multiply or divide a binary number
left shift ultiplies
right shift divides
the effect is doubled by each place that is shifted
What is a character set and why are they needed?
a defined list of characters recognised by the computer
each character in a set has a unique binary number matched with it
logically ordered
necessary as they allow computers to exchange data and humans to input characters
What are the similarities and differences between ASCII and unicode?
the number of characters stored is limited by the bits available
ASCII - 8 bits 256 possible characters - enough for only english language - takes less memory space
unicode - 16 bits 65,536 characters - allows many different languages, text symbols and eojis to be represented - takes more meory to store each character
file size of text file
bits per character x number of characters
How is an image is represented
as a series of pixels represented in binary
each pixel is assigned a binary value for the colour
What is the effect of colour depth and resolution?
the total number of pixels - image resolution
colour depth - number of bits used to represent each pixel’s colour
increasing these increases quality but also file size
What is metadata
stores additional image information
How can sound can be sampled and stored in digital form?
amplitude of analogue wave is measured and recorded at fixed intervals and converted to pinary
it is discrete
What is the effect of sample rate, duration and bit depth?
Duration – how many seconds of audio the sound file contains
Bit depth – number of bits available to store each sample
to get the highest quality sound, many samples are taken to recreate the analogue wave as closely as possible
sample rate - number of times per second the amplitude of the wave is measured
the higher the saple rate, the better the quality - higher file size because more data is stored for each individual sample
higher bit depth - better quality but greater file size
sound file size
bit depth x sample rate x duration
