Chapter 3 · Data Representation
Hours: 10 · Difficulty: ★★★☆☆ · Foundation for: Module B (CPU), Module D (programming), Elective 2C (algorithms)
This is the largest sub-topic in Module A and the number-systems backbone of the whole subject. Master this and Paper 1's number-related questions become free marks.
Chapter contents
| # | Topic | Approx. study time |
|---|---|---|
| 3.1 | Analog vs digital data | 30 min |
| 3.2 | Number systems (binary, hex) | 90 min |
| 3.3 | Binary arithmetic & overflow | 60 min |
| 3.4 | Two's complement | 60 min |
| 3.5 | Character encoding | 60 min |
| 3.6 | Multimedia digitisation | 90 min |
| 3.7 | File formats | 60 min |
Learning outcomes
- Distinguish analog from digital data and recognise when one must be converted to the other.
- Convert integers between denary, binary and hexadecimal in both directions.
- Perform binary addition and subtraction and analyse overflow.
- Adopt two's complement for negative integers.
- Know how characters are represented using ASCII, Big-5, GB and Unicode.
- Briefly describe how images, audio and video are digitised.
- Compare common multimedia file formats (bmp, png, jpg, wav, mp3, avi, mpeg4, txt, docx, odt, pdf).
How to study this chapter
- Practice conversion every day for one week, 5 minutes a day. Speed beats theory.
- Use scrap paper. Number systems are easy if you write them out, infuriating if you try in your head.
- Cross-check with Python. Open a terminal and run
bin(213)andhex(213). Confirm by hand.
➡️ Start with: 3.1 Analog vs Digital