Coding Text in Binary

Introduction

• Discuss the systems for coding character data: ASCII and Unicode.
• Explanation of why Unicode was introduced.

ASCII Coding System

• Bits are grouped into 8-bit bytes in most computers.
• A byte can represent 256 different combinations of zeros and ones.
• One byte is used to code one unique character.
• ASCII uses only 7 bits for each character, leaving the 8th bit for error checking.
• Provides 128 unique codes for:
  • Lowercase and uppercase English alphabet
  • Digits 0 to 9
  • Punctuation and special characters
  • Non-display signals (e.g., null, escape key)
• Limitation: Different computers might use different sets of codes.
• ASCII is widely used in personal computers as the American Standard Code for Information Interchange.

Limitations of ASCII

• ASCII's 128 character limit is restrictive for:
  • Special characters in European languages.
  • Diagrammatic fonts in languages like Chinese and Korean.
• ASCII cannot represent all these characters due to limited unique values.

Unicode Coding System

• Designed to overcome ASCII limitations by providing a larger character set.
• Unicode versions are at least 16 bits long.
• Offers a vast number of combinations:
  • Covers over 120,000 characters.
  • Includes 129 modern and historic scripts, as well as symbol sets.
• "Unicode" signifies its universal capability to encode almost all modern and ancient languages.

Downsides of Unicode

• Requires twice as much space to represent each character compared to ASCII.

Conclusion

• Unicode addresses the limitations of ASCII by offering more comprehensive language and character support, albeit with increased space requirements.