Information Layer
IB Syllabus: A1.2 — Data representation and computer logic
Table of Contents
Overview
The Information Layer deals with how data is represented inside a computer. At the hardware level, every piece of information — numbers, text, images, sound, and video — must be encoded as patterns of binary digits (bits). Understanding these encoding methods is essential for appreciating how computers store, process, and transmit information.
This layer covers A1.2.1 (number systems and conversions) and A1.2.2 (binary representation of data types). The remaining A1.2 outcomes — A1.2.3–A1.2.5 (logic gates and Boolean algebra) — are covered in the Hardware Layer since they relate directly to how CPUs process binary signals.
Sub-pages
| # | Topic | Syllabus | Key Concepts | Level |
|---|---|---|---|---|
| 1 | Number Systems | A1.2.1 | Binary, hexadecimal, decimal; conversions between all three; two’s complement | SL + HL |
| 2 | Representing Data | A1.2.2 | Characters (ASCII/Unicode), images (bitmap/RGB), audio (PCM/sampling), video (frames/compression) | SL + HL |
Teaching Sequence
These topics follow the classroom teaching order (W4–W7), starting with number systems as the foundation for understanding how all data is encoded:
- Number Systems (W4) — Binary, hexadecimal, decimal conversions
- Characters & Integers (W6) — Two’s complement, ASCII, Unicode
- Images, Audio & Video (W7) — RGB, bitmap, sampling, PCM, frame rates
Learning Objectives
By the end of this topic, you should be able to:
- Describe binary, hexadecimal, and decimal number systems and convert between them (A1.2.1)
- Explain how integers are represented in binary, including two’s complement for negative numbers (A1.2.1)
- Explain how characters are encoded using ASCII and Unicode (A1.2.2)
- Explain how images are stored using pixels, resolution, and colour depth (A1.2.2)
- Explain how audio is digitised using sampling rate, bit depth, and PCM (A1.2.2)
- Explain how video combines image frames with audio, and why compression is essential (A1.2.2)
- Calculate file sizes for images, audio, and video given their parameters (A1.2.2)
Connections
- Hardware Layer — Logic Gates (A1.2.3–A1.2.5) process the binary signals described here; Primary Memory stores binary data; Compression reduces the file sizes calculated in data representation
- Programming Layer — Variables & Data Types uses binary storage at the language level; File Processing reads and writes encoded data
- Communication Layer — Data representation underpins how information is transmitted across networks