Data Representation - Characters (ASCII and Unicode) Flashcards
What are character sets?
Collections of characters that a computer recognises from their binary representation
How are alphanumeric characters used?
To make words and strings
What happens when you press a button on the keyboard?
It sends a binary signal to the computer telling it which key you pressed
How many bits are in ASCII?
7-bit which means 128 different characters
What characters does ASCII include?
All letters in the English alphabet, numbers, symbols and commands
Why is an extra bit (usually 0) sometimes added to the start of binary code for each ASCII character?
So that it fits nicely into 1 byte
What does ASCII stand for?
American Standard Code for Information Interchange
How are characters ordered in ASCII?
They are in order - A comes before B which comes before C
Symbols and commands are scattered around
What is extended ASCII?
8-bit binary code used to represent 256 characters - first 128 are the same as 7-bit ASCII but with a 0 in front
Why is extended ASCII used?
To represent other things like math symbols and characters from other languages (German or French)
What is the major advantage of using Unicode?
It covers all major language - Greek, Russia, Chinese…
What are the first 128 codes in Unicode?
The same as ASCII
What is Unicode?
Comes in different forms and tries to cover every possible letter or symbol that might be written
What are the two common character sets?
ASCII
Unicode
How is Unicode different to ASCII.
Unicode uses multiple bytes for each character where ASCII uses 1 byte per character
