Data Flashcards
Why do computers use
binary?
(Long explanation + short explanation)
We live in an analogue world since colours and sounds are all described by real numbers - there are an infinite number of them. (This is also referred to as continuous data.)
Digital signals and objects deal in the realm of the finite, meaning there is a limited set of values they can be.
Computers are made of digital switches (transistors) that can either be on or off. We use binary digits (bits) to represent their state.
Using binary values allows us to represent information on the transistors that make up a computer.
What is the relationship between
length of binary pattern and number of states that can be represented?
number of states that can be represented = 2^number of bits (in the binary pattern)
What are
decimal multiple of bytes used for?
data transmission speeds
i.e. kilobyte (kB), megabyte (MB) …
What are
binary multiples of bytes used for?
file sizes
i.e. kibibyte (KiB), mebibyte (MiB) …
What are the
multiples of bytes?
(in ascending order)
burger - byte
king - kibibyte/kilobyte
made - mebibyte/megabyte
great - gigibyte/gigabyte
toast - tebibyte/terabyte
previously - pebibyte/petabyte
(but - bit
now?) - nibble
Define
overflow error.
the error that ocurs when the number of bits reserved for the result of a calculation are not enough to store all the bits from the number
What is
two’s complement?
a method that allows for negative number representation where the most significant bit is negative
How would you
convert negative denary numbers to two’s complement?
(3 steps)
- Turn the negative denary number into a positive binary number.
- Flip the bits (0 -> 1, 1 -> 0).
- Add 1.
What are
binary shifts?
shifts that are used to move all the bits in a binary pattern left or right
What are
logical shifts
shifts that treats all the bits of a binary pattern in the same way, irrespective of what the pattern represents
Why can
loss of precision occur during a logical shift right?
because one or more of the right-most bits are discarded during the shift
What is special about an
arithmetic shift right?
and what is this good for?
the most significant bit is preserved
this is good because it gives us the ability to divide negative numbers
What are some
positives of hexadecimal?
(3)
- it takes up less space on the page to write numbers
- you make fewer mistakes when writing large numbers
- it is quicker to write down/copy/transcribe
What is
ASCII?
and what does it stand for?
a 7-bit character set
American Standard Code for Information Interchange
Define
colour depth.
the number of bits used to encode the colour of each pixel
What is
image size?
the total number of pixels along an image’s width and height
What is
resolution measured in?
pixels per inch (PPI)
aka dots per inch (DPI)
What equaiton links
physical width, image width and resolution?
image width = physical width x resolution
width can be replaced with height
What is the equation for
image size in bytes?
image size in bytes = (number of pixels x colour depth) / 8
Define
amplitude.
the extent to which air particles are displaced
in other words, the loudness of the sound
Define
bit depth.
(in relation to represnting sound)
the number of bits stored per sample
the higher the number of bits, the greater the quality of the sound, and the larger the file size
Define
sample interval.
the amount of time which passes between capturing each sample
Define
sample rate.
the number of samples stored per second
the higher the number of samples per second, the higher the quality of the sound, and the larger the file size
What is
FLAC used for?
and what type of compression does it use?
sound
lossless
What is
JPEG used for?
and what type of compression does it use?
image
lossy
What is
MP3 used for?
and what type of compression does it use?
sound
lossy
What is
WAV used for?
and what type of compression does it use?
sound
uncompressed
What is
ZIP used for?
and what type of compression does it use?
file archives
lossless
What is
PNG used for?
and what type of compression does it use?
image
lossless
What is
MP4 used for?
and what type of compression does it use?
video
lossy
What is
BMP used for?
and what type of compression does it use?
image
uncompressed
What does
lossless compression do?
reduces the size of a file while retaining the exact meaning of the original data
What does
lossy compression do?
reduces the size of a file (by up to 90%) by permanently deleting some of its data
