Data Representation Flashcards
base of denary
10
base of binary
2
base of hexadecimal
16
why do computer systems use hexadecimal
Hexadecimal is easier for humans to understand than binary, as it is a shorter representation of
the binary. It is used to represent colour and simplify binary
how to converted negative binary (two’s complement) to denary?
add all as normal and add result from -128
what happens when you shift one left
number multiplies by 2
what happens when you shift one right
number divides by 2
what does ASCII stand for
american standard code for information interchange
how many bits does ASCII have
7 - represents 128 characters
how many bits does ASCII extended have
8 - represents 256 characters
how many bits does unicode use
8 to 32 bits (larger files occupy more space)
available character sets in unicode
letters, numbers, symbols, emojis non-visual
why is a sound wave sampled
to be converted to binary
what is sampling
process performed by computer to convert analogue to digital waves
if more analogue waves are sampled…
….more data is gathered
what are analogue waves compared to digital
analogue = continuous
digital = discrete
what is sample rate
number of samples taken in a second
what is sample resolution
number of bits per sample
how does accuracy of recording and file size increase
as sample rate and resolution increase
what is an image
series of pixels that are converted to binary, which is processed by a computer
what is bit depth
how many bits are used to store the colours in each pixel of the image
what is resolution
number of pixels in image
what is colour depth
number of bits used to represent each colour
file size and quality of image increases as
the resolution and colour depth increases
measurements for data storage
- bits
- nibble (4 bits)
- bytes (8 bits)
- kibibyte (1024 bytes)
- mebibyte (1024 kibibytes)
– gibibyte (GiB)
– tebibyte (TiB)
– pebibyte (PiB)
– exbibyte (EiB)
what does compression do
reduces size of file
what is lossless compression
reduces file size without permanent loss of data
example of lossless compression
run length encoding (RLE)
what is lossy compression
reduces file size by permanently removing data
example of lossy compression
reducing resolution of colour depth
reasons for data compression to occur
- save storage capacity
- speed up file transfer
- decrease cost for hardware
How and why do computers use binary to represent all forms of data
- Any form of data needs to be converted to binary
to be processed by a computer - Data is processed using logic gates and stored in
registers
Concept of overflow and why
it occurs in binary addition
- An overflow error will occur if the value is greater
than 255 in an 8-bit register - A computer or a device has a predefined limit
that it can represent or store, for example 16-bit - An overflow error occurs when a value outside
this limit should be returned
How and why are ASCII and Unicode used
- Text is converted to binary to be processed by a
computer - Unicode allows for a greater range of characters
and symbols than ASCII, including different
languages and emojis - Unicode requires more bits per character than
ASCII
