Character Sets + ASCII + Unicode | 2.4 | OCR GCSE Computer Science | J27

17 flashcards

Character set: A collection of all characters that a computer can represent.
What are character sets essential for?: Exchanging data and inputting text.
What do characters mapped by a character set include?: - letters - numbers - symbols - emojis - control characters (in some character sets)
American Standard Code for Information Interchange (ASCII): A character set that is used to map characters to unique binary values.
How many bits does ASCII use to represent each character?: 8 bits (1 byte)
How many characters does ASCII allow?: 256 characters (2⁸)
What is an advantage of ASCII?: It uses only 1 byte per character, so it takes up less memory space than other character sets (e.g. Unicode, which uses 2 bytes per character)
ASCII vs Unicode: How many bytes would the word 'apple' be?: ASCII: 5 bytes Unicode: 10 bytes
What is a disadvantage of ASCII?: It only uses 1 byte, which allows for 256 characters This means that other languages (e.g. Arabic/Chinese) or other symbols (e.g. emojis) cannot be represented.
Unicode: A character set that is used to map characters to unique binary values.
Why is Unicode the most popular character set?: Because it can represent thousands of characters.
How many bits does Unicode use to represent each character?: 16 bits (2 bytes)
How many characters does Unicode allow for?: 65,536 characters (2¹⁶).
What is an advantage of Unicode?: Having an extra byte over ASCII allows many more characters to be represented - this includes all languages and thousands of symbols and emojis.
What is a disadvantage of Unicode?: It takes up more memory to store each character as it uses 2 bytes rather than ASCII's 1 byte.
ASCII vs Unicode: How many bytes would the phrase 'oak tree' be?: ASCII: 8 bytes Unicode: 16 bytes
Why is Unicode backwards-compatible with ASCII?: The first 128 values of Unicode are the exact same as in ASCII.