Lecture Notes: Real-Time Data Storage in Computers

Introduction

• Focus: Understanding how real-time data is stored in computers.
• Background: Previous discussions on main memory and mass storages.
• Objective: Learn the internal storage of textual data in binary form.

Binary Language

• Computers understand only binary (0s and 1s).
• Real-world data like text is converted to binary for storage.

Representing Text in Binary

• Concept: Each textual symbol is represented by a unique bit pattern.
• Example: A pattern like 0110001 for a symbol.
• 8-bit Pattern: Standard pattern length for each textual symbol.

ASCII (American Standard Code for Information Interchange)

• Development: Codes developed in the 1940s and 1950s.
• Authority: American National Standards Institute (ANSI).
• Structure: ASCII uses 7 bits for representation, allowing 128 combinations.
• Symbols: Includes uppercase, lowercase, punctuation, digits (0-9), line feed, carriage return, and tabs.
• Page Reference: ASCII codes can be found in Appendix A, page 577.

Limitations of ASCII

• ASCII supports 128 symbols, which is insufficient for global character representation.

Extensions and Solutions

ISO (International Organization for Standardization)

• Developed extensions for different languages but faced issues with multi-language documents.

Unicode

• Purpose: To internationalize character representation with unique 21-bit patterns.
• Compatibility: Unicode is ASCII-compliant.
• Capacity: Represents over 2 million symbols, covering Chinese, Japanese, etc.
• UTF-8: Uses 24 or 32 bits, representing 16 million unique symbols.

Text Files

• Files encoded with ASCII or Unicode are typically referred to as text files.

Summary

• Key Learnings: Text representation in computers using binary, ASCII, and Unicode.
• Impact: Easier data storage and representation across different languages and symbols.