Information Layer
A1.2 - Data representation and computer logic
Overview
The Information Layer covers how computers represent data. At the hardware level, every kind of information, including numbers, text, images, sound and video, has to be encoded as patterns of binary digits (bits). These pages explain those encodings, how they let computers store, process and transmit information, and how to calculate storage requirements.
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 |
Suggested learning order
Start with number systems, then explore how computers encode text, images, audio and video:
- Number Systems - Binary, hexadecimal, decimal conversions
- Characters & Integers - Two’s complement, ASCII, Unicode
- Images, Audio & Video - 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