3.3 Fundamentals Of Data Representation Flashcards
How is binary used by computers ?
- binary is used by computer to represent all data and instructions, as 0’s and 1’s
What are the different magnitude of bits ?
Bit - 0 or 1
byte - 8 bits
kilobyte - 1000 bytes - kB
megabyte - 1000 kilobytes - MB
gigabyte - 1000 megabytes - GB
terabyte - 1000 gigabytes - TB
What are the uses of hexadecimal ?
Hexadecimal numbers are shorter and easier to read and remember, and quicker to type:
- MAC addresses
- memory addresses locations in assembly language
- colour values in HTML
What is the effect of a binary shift ?
- shift to the left multiplies the number by 2
- shift to the right divides the number by 2
- problems can occur when an odd number is divided, a standard byte cannot represent fractional number, this can cause one or more 1’s being lost at the right side, causing a loss of accuracy called an underflow error
What is a character set ?
A character set consists of all the letters, numbers and special characters that can be recognised by a computer system
What is ASCII and Unicode ?
ASCII - uses 7 Bits per character meaning there can be a total of 128 characters, all of which is taken up by the English language
Unicode - uses 16 bits per character meaning it can represent over 65,000 characters, which can represent characters of all international languages and emojis
What is a pixel?
A pixel is the smallest identifiable and addressable part of an image, each one representing a single colour
What is the colour depth of an image ?
- number of bits used to represent each pixel
- 2 to the power of colour depth can tell you how many colours can be represented
What is the effect of colour depth on the file size
- the greater the colour depth, the greater the quality of the image as more colours can be represented
- the greater the colour depth, the more bits needed to be stored to represent each pixel, increasing the file size
- file size = width x height x colour depth
How is sound stored on a computer ?
sound is analogue - its sound waves are continuously changing, however anything stored on a computer must be stored digitally as a series of binary numbers, therefore sound needs to be converted into digital form before it can be stored, this is done by sampling the amplitude of the sound wave and storing these samples as binary values
What is the sampling rate ?
- the frequency at which you record the amplitude of the sound ie the number of samples per second
- measured in hz
- the higher the sample rate, the better quality the playback sound will be
What is the sample resolution ?
- the number of bits used to store a sample
- the greater the sample resolution, the amplitudes of the sound are more accurately represented
How to calculate the size of an audio file ?
File size = sample rate x sample resolution x duration (s)
What is data compression ?
Compression software uses algorithms to remove repeated or unnecessary data, to reduce the amount of bits/bytes needed to store the file
Why is data compressed ?
- reduce the amount of storage needed to save files
- allows large files to be transmitted easier as email attachments to meet attachment limits
- files can be transmitted quicker, streamed video content can be downloaded and uploaded faster
