Unit 6: The Internet and it's use (IGCSE Computer Science)

This material is designed to help students prepare for Paper 1. It includes a compilation of all the questions from Unit 1: Data Representation, presented in PowerPoint format. This format allows for easy assignment distribution and efficient grading. I have personally used these resources in class, and they have proven to be both time-saving and effective. The questions are arranged in chronological order, from the earliest to the most recent. These materials are ideal for students taking the test this year.

In this chapter you will learn about:

1. number systems

• how and why computers use binary to represent data
• the denary, binary and hexadecimal number systems
• converting numbers between denary, binary and hexadecimal
• how and why hexadecimal is used for data representation
• how to add two positive 8-bit numbers
• overflow when performing binary addition
• logical binary shifts on positive 8-bit integers
• two’s complement notation to represent positive and negative binary numbers

1. text, sound and images

• how and why a computer represents text
• the use of character sets including ASCII and Unicode
• how and why a computer represents sound
• sound sample rate and sample resolution
• how and why a computer represents an image
• the effects of the resolution and colour depth on images

1. data storage and compression

• how data storage is measured
• calculating the file size of an image and sound file
• the purpose of and need for data compression
• lossy and lossless compression.