Unicode vs ASCII
What are Unicode and ASCII?
- Unicode and ASCII are both character encoding systems
- They allow computers to store and represent text using binary (0s and 1s)
- Each character (e.g. A, b, 7, £) is given a numeric value
| Extended ASCII | Unicode | |
|
Description |
A basic, fixed system for Western text |
A universal system for every language and symbol |
| Bits Used | 8 bits |
Variable (8, 16, 24, or 32 bits) |
| Number of Characters | 256 available characters |
Over 1 million available characters |
Unicode is highly flexible. While it stays at 8 bits for simple text to save space, it has the ability to expand its bit-count in 8-bit increments. By reaching a maximum of 32 bits, it provides enough space for over a million unique characters. This ensures it only ‘pays’ the higher bit cost when a character actually needs the extra room to reach its higher ‘assigned number’.
Example exam question
Question:
A developer is choosing between Extended ASCII and Unicode for a new global messaging app. Describe one advantage of using Unicode over Extended ASCII. You must make reference to the number of bits used to represent a character in each format. (2 marks)
Answer:
– Unicode represents over 1 million characters, which is far more than the 256 characters in Extended ASCII. (1 mark)
– This is because Unicode uses a variable number of bits (up to 32), while Extended ASCII is limited to a fixed 8 bits. (1 mark)