1. data representation Flashcards
how and why 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
difference between denary, binary and
hexadecimal number systems
Denary is a base 10 system
Binary is a base 2 system
Hexadecimal is a base 16 system
positive denary -> positive binary
and vice versa
practice
positive denary -> positive hexadecimal
and vice versa
practice
positive hexadecimal -> positive binary
and vice versa
practice
what is hexadecimal? what is its function
base 16 system used to represent binary numbers in a more human-friendly form,A simpler way to remember binary-equivalent values, more possible values with a smaller/ shorter representation, and finally its used normally for colours and error messages
adding binary
practice
subtracting binary
practice
what is an overflow and why does it happen in binary addition
Overflow errors occur when a computer system attempts to occupy its registers with value that is one bit larger than its capacity
perform left and right logical shifts
practice
what happens to the denary value of a binary number when performing a left logical shift
multiplies depending on the amount of shift 1= x2
what happens to the denary value of a binary number when performing a right logical shift
divides depending on the amount of shifts eg 1= /2
Use two’s complement to represent positive and negative 8-bit binary integers
practice
Convert a positive binary or denary integer to a two’s complement 8-bit integer and vice versa
practice
Convert a negative binary or denary integer to a two’s complement 8-bit integer and vice versa
practice
how does a computer know that a two’s complement number is negative
1 in leftmost value/ digit
how do computers represent texts
using binary digit, unique to each character so that it can be processed by a computer
what is ascii
standard code for info interchange, used worldwide to represent characters in a computer system.
uses 7 bits to encode characters, can represent 128 characters
what is unicode
uses 16 bits, developed after ascii because some languages use their unique characters, and didnt fit the character set provided by ascii
what are digital sounds used by computers made up of?
digital waves, a sequence of ‘discrete’ signal meaning a complex series of ‘on’ and ‘off’ instructions.
whats the difference between analogue and digital waves
analogue are what humans use as sound and digital is what computers use
analogue waves are smooth and digital waves arent
what is sampling
the process in which a computer converts analogue waves into digital waves, to do this it takes measurments of; sample resolution and sample rate
what is sample resolution
The number of bits used per sample.
what is sample rate
The number of samples of an analogue audio signal taken in a second
what happens to file size when we increase resolution
increases
what happens when we increase the frequency/ sample rate of a sample, in regards to the file
file increases
how are images stored in a computer
using binary digits, and pixels
pixels are the smallest identifiable measurements in an image, each pixel is given a binary number that relates to a specific colour
what is image resolution
the number of pixels within an image, and this is normally described using the width and height of the image
what happens when you increase the number of pixels in an image
the higher the resolution/ clearer better image, and the larger the file size
give the units for storing data and what “they are made of”eg how many bits in a byte
bit- binary digit 1 or 0 (b)
nibble- 4 bits
byte- 8bits (B)
kibibyte- 1024 bytes (KiB)
mebibyte- 1024 kibibytes (MiB)
gibibyte- 1024 mebibytes (GiB)
tebibyte- 1024 gibibyte’s (TiB)
pebibyte- 1024 tebibyte’s (PiB)
exibibyte- 1024 pebibyte’s (EiB)
what is the formula for image file size
(image width × image height) × bit depth
what is the formula for sound file size
= sample rate × sample resolution × length of track
what is 1KHz
1000 samples per second
what is compression
The act of reducing the logical size of a file to something much smaller than the original size, to save storage space and improve processing time. by applying an algorithm
benefits of compressing a file
-less bandwidth required (less time loading it)
– less storage space required
– shorter transmission time (sending it to someone)
what is lossy compression
permanently removes some data from the original source file, meaning lower quality files
uses an algorithm that looks to remove detail that is barely noticeable
usedin files such as mp3, jpgs
not used for text documents
what is lossless compression
does not lose any data from original file, produces larger files that lossy but better quality,does not remove quality
uses an algorithm that looks for repeat data, this can be groups and categorised and a token be given for where each group will be used in the reconstruction
often used in file texts and images eg. docx gifs pngs
