GCSE
Computer Science
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Introduction to GCSE Computer Science -
1.1 Systems Architecture -
1.2 Memory and Storage -
1.3 Computer Networks, Connections and Protocols -
1.4 Network Security -
1.5 Systems Software -
1.6 Ethical, Legal, Cultural and Environmental Impacts of Digital Technology -
2.1 Algorithms -
2.2 Programming Fundamentals -
2.3 Producing Robust Programs -
2.4 Boolean Logic -
2.5 Programming Languages and Integrated Development Environments
1. Computer Systems
In this lesson, we will explore how computers use binary to represent characters. We will cover ASCII, Unicode, and how bit length affects character storage and processing.
Binary Codes for Character Representation
In computing, characters, such as letters, digits, punctuation marks, and special symbols, are represented using binary codes. Binary is a base-2 numbering system that uses only two digits, 0 and 1. Each binary digit is called a "bit," and a sequence of bits is used to represent different characters and instructions within a computer.
To standardise how characters are stored and transmitted, several character encoding systems were developed, the most common being ASCII (American Standard Code for Information Interchange).
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Create a free accountBinary Codes for Character Representation
- Computers use binary codes to represent characters such as letters, digits, and symbols.
- A character set is a collection of characters each mapped to a unique binary code.
- The number of bits per character determines how many characters can be represented.
- ASCII is an early character set using 7 bits (128 characters); extended ASCII uses 8 bits (256 characters).
- ASCII includes control characters, digits, punctuation, and both uppercase and lowercase letters.
Binary Representation of ASCII in 8 Bits
- In 8-bit ASCII, each character is represented using one byte.
The Relationship between Bits per Character and Number of Characters
- The number of characters in a set is calculated using: \(\text{Number of Characters} = 2^{\text{Number of Bits}}\)
- 8-bit ASCII can represent 256 characters; 16-bit Unicode can represent 65,536 characters.
The Power of Unicode
- Unicode uses 16 bits and can represent characters from nearly every language and writing system.
- It supports emojis, symbols, and scripts from across the globe.
- Unicode allows consistent character representation across different systems and devices.