Character Encoding
Overview
Memory holds numbers. Text is not numbers. Somewhere between the key you press and the letter that appears there has to be an agreement, written down and obeyed by every piece of hardware and software in the chain, that this particular pattern of bits means the letter H. That agreement is a character set, and the whole reason you can send a message from a phone in one country to a laptop in another and have it arrive readable is that both ends are using the same one.
This lesson covers the two encoding methods the specification names, 7-bit ASCII and Unicode. You will learn what a character set actually is, why the codes inside one are arranged in runs rather than scattered, how to use a given table to go from characters to codes and back, and why a scheme with only 128 codes could not serve a world that writes in hundreds of scripts. You will also meet the single most useful consequence of the sequential arrangement: once you know one code in a group, you can work out the rest by counting.
Objectives
- Understand what a character set is and be able to describe the following character encoding methods:
- 7-bit ASCII
- Unicode. Understand that character codes are commonly grouped and run in sequence within encoding tables.
- Describe the purpose of Unicode and the advantages of Unicode over ASCII.
- Know that Unicode uses the same codes as ASCII up to 127.
Mind map
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Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Character Encoding. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- How many different characters can be represented using 7-bit ASCII? A. 7 B. 64 C. 128 D. 256 Answer: C
- In ASCII the character A has the code 65. What is the character code for D? A. 66 B. 67 C. 68 D. 69 Answer: C
- Which statement about Unicode is correct? A. Unicode can represent fewer characters than ASCII B. Unicode uses the same codes as ASCII up to 127 C. Unicode uses exactly 7 bits for every character D. Unicode cannot represent the English alphabet Answer: B
- The character codes for the lower case letters begin with a at 97. What is the code for the letter d? A. 99 B. 100 C. 101 D. 104 Answer: B
- Why are the character codes for the capital letters stored in sequence? A. So that the codes for the rest can be worked out once one is known B. So that capital letters take up less memory than lower case letters C. So that the codes can be stored without using any bits D. So that the same code can mean two different characters Answer: A
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