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Year 10 - Computing

Representing text using ASCII and Unicode

Representation of text, images and sound

Unit Summary

In this unit, pupils will discover how letters, images and sounds are represented with binary digits. They will also explore the factors that impact the quality of those representations and investigate the effects these quality choices have on file size.

Lesson Summary

You will learn to explain how computers represent text.

Key Notes

  • The number of possible states of a sequence of n bits is 2 raised to the power of n.
  • A character set is a record of characters, each matched to a unique binary sequence.
  • ASCII character representation uses an 8-bit binary sequence to represent each character.
  • Unicode character representation uses up to 32 bits to represent each character.
  • The first 256 characters of Unicode are the same as in ASCII.

Vocabulary To Learn

  • state: value of data at a specific point in time
  • character set: a record of characters matched to a unique binary sequence
  • ASCII: a character set that represents each character with a unique numerical value
  • Unicode: a method of character representation that uses up to 32 bits per character

Common Mistakes To Avoid

  • ASCII and Unicode are only used to represent the characters and symbols found in written communication across all languages in the world.

3 Quick Questions (With Answers)

1. Describe the system or process from this lesson in clear steps.

The number of possible states of a sequence of n bits is 2 raised to the power of n. A character set is a record of characters, each matched to a unique binary sequence.

2. Define this computing term and give one practical example. 'state'

value of data at a specific point in time. Add one real device or system example to prove understanding.

3. Correct this common computing misconception.

Mistake: ASCII and Unicode are only used to represent the characters and symbols found in written communication across all languages in the world. Correction: ASCII and Unicode include more than just characters from written languages. ASCII represents English letters, numbers and symbols. Unicode supports other symbols beyond written text, including mathematical symbols, emojis and non-text elements.

More Lessons In This Unit

Browse all guides in the Year 10 Computing guide library.