CIE Computer Science IGCSE - Unit 1. Data Representation

This first unit of the course contains the explanations about how integer numbers, text, sound and images are stored in a computer system. Also, an introduction to compression is explained including the types of compression, the most used formats and the explanation of why compression is needed in Computer Science.

The unit contains 72 pages divided into three sections:

• 1. Number systems
• 2. Text, sound and images and
• 3. Data Storage and Compression.

This unit contains the following contents:

• a revision of how numbers are represented using symbols
• a revision of how decimal system works
• explanation of binary and hexadecimal number systems and the symbols used
• examples of conversions of numbers between number systems
• explanation of the binary addition
• understanding of what is an overflow and in which cases it may occur
• explanations of logical right and left shifts with examples
• representations of positive and negative integers using two’s complement
• a wide explanation of what is a character set incluing ASCII and Unicode
• definitions and an explanation of the process of converting analogue sound into digital
• definitions about images and explanations of how bitmap images are stored on a computer system
• an introduction of the storage measurement units such as the multiples of the bit and byte and how to convert between them
• explanation and examples of why is compresion needed
• explanation of the two types of compression, including lossless and lossy, their advantages/disadvantages and their current use in Computer Science

Syllabus objectives, schemes and graphics are provided for better understanding.