0984
Text, Sound and Images
Data Representation · 3 question types
Exam Frequency Analysis
Past paper frequency (2018 to 2024)
This topic accounts for approximately 5% of your exam marks.
stable
Rare
Stable5%
ASCII/Unicode, sound sampling and pixel/colour depth appear regularly as 2 to 4 mark questions.
This comparison comes up almost every year. The mark scheme wants precise statements.
| Feature | ASCII | Unicode |
|---|---|---|
| Bits per character | 7 (or 8 for extended) | 16+ |
| Number of characters | 128 (or 256) | 65 536+ |
| Storage space per character | Small | Large |
| Languages covered | English only | All major world languages |
| Emoji and modern symbols | No | Yes |
| Best use | English text on systems with limited memory | International text, web pages, modern software |
Trade-offs in a single sentence
- stores more characters but uses more memory per character.
- uses less memory but cannot represent international text or emoji.
Mark-scheme language: when comparing, mention the number of bits, the number of characters, and what each can represent. Vague answers like "Unicode is bigger" or "Unicode is better" do not score.