This key facts covers ASCII: The Foundation (1963) within Character Sets for GCSE Computer Science. Revise Character Sets in Memory & Storage for GCSE Computer Science with 15 exam-style questions and 18 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 3 of 10 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 3 of 10
Practice
15 questions
Recall
18 flashcards
ASCII: The Foundation (1963)
ASCII = American Standard Code for Information Interchange
Key Facts:
- 7 bits: 2⁷ = 128 possible characters (0-127)
- Coverage: English alphabet, numbers, punctuation, control codes
- Designed for: English language, teletype machines, early computers
- File size: 1 byte per character (8 bits, with 1 bit spare)
ASCII Character Ranges:
0-31: Control characters (e.g., newline, tab, delete)
32: Space
33-47: Punctuation (! " # $ % & ' ( ) * + , - . /)
48-57: Digits (0-9)
58-64: More punctuation (: ; < = > ? @)
65-90: Uppercase letters (A-Z)
91-96: Brackets and symbols ([ \ ] ^ _ `)
97-122: Lowercase letters (a-z)
123-127: More symbols ({ | } ~ DEL)
Common ASCII Codes (Memorize These!):
| Character | ASCII Code | Binary | Hex |
|---|---|---|---|
| 0 (digit) | 48 | 00110000 | 30 |
| 9 (digit) | 57 | 00111001 | 39 |
| A (uppercase) | 65 | 01000001 | 41 |
| Z (uppercase) | 90 | 01011010 | 5A |
| a (lowercase) | 97 | 01100001 | 61 |
| z (lowercase) | 122 | 01111010 | 7A |
| Space | 32 | 00100000 | 20 |
Clever ASCII Patterns:
- 'A' = 65, 'B' = 66, 'C' = 67... Sequential codes make alphabetical sorting easy
- Uppercase → Lowercase: Add 32 ('A' (65) + 32 = 'a' (97))
- Digit characters: '0'=48, '1'=49... To get numeric value, subtract 48