Information Representation in a machine

Summary

This course introduces modern application development, focusing on markup languages and how they control the display of content on a screen, shaping the aesthetics of user interfaces. It explains key concepts like information representation, the distinction between raw data and semantics, and the difference between logical structure and presentation. The course also covers encoding standards like ASCII and Unicode, tracing the evolution from 7-bit codes to modern systems like UCS-4 that can handle millions of characters, ensuring compatibility across languages and systems.

Takeaways

• 📜 Markup is essential for controlling how content is displayed to users, contributing to a website's aesthetics and usability.
• 🖥️ Computers process and store data as binary (0s and 1s), which is robust against noise and environmental disturbances.
• 🔢 Binary encoding allows computers to represent numbers, with specific conventions like 2's complement for negative numbers.
• ✉️ Text encoding is crucial for communication between machines and between humans and machines, requiring standardization.
• 🔤 ASCII was the original 7-bit standard used to represent characters, sufficient for basic English text and numbers.
• 💻 Extended ASCII later added 8-bit encoding to support more characters, accommodating additional European symbols and accents.
• 🌍 The Unicode standard was developed to represent characters from global scripts, moving beyond ASCII's limitations.
• 🗺️ Unicode provides encoding for thousands of characters, covering various scripts, past and present, while leaving room for expansion.
• 📝 Early Unicode used 2 bytes per character (UCS-2), later expanded to 4 bytes (UCS-4) to support billions of potential characters.
• 🔧 Only around 100,000 characters are currently defined in Unicode, though the system allows for billions, ensuring flexibility.

Q & A

What is the purpose of markup in modern application development?

Markup is used to control how content is displayed on the screen, influencing the aesthetics and user interface of a website or application. It allows developers to define the presentation and style of information, making it an essential component of user interaction.

What distinction is made between raw data and semantics in the context of information representation?

Raw data refers to the basic form of information stored in bits (0s and 1s), while semantics involve the meaning or interpretation of that data. Understanding the difference helps distinguish between the structure of information and its visual or functional presentation.

How are binary digits used to represent numbers in computers?

Binary digits (bits) are used to represent numbers using a place value system based on powers of 2. For example, the binary sequence '0110' represents the number 6. The interpretation of these bits depends on their context, such as whether they are signed or unsigned numbers.

What is ASCII, and why was it developed?

ASCII stands for American Standard Code for Information Interchange. It was developed to standardize the encoding of characters (letters, numbers, and symbols) as binary sequences, enabling the consistent exchange of information between machines and between humans and computers.

Why did ASCII originally use 7 bits, and how was it extended later?

ASCII originally used 7 bits to represent characters, as this was sufficient to encode the English alphabet, digits, and common symbols, while being efficient in terms of memory usage. Later, an 8-bit extended ASCII format was introduced to accommodate additional characters needed for other languages.

What is Unicode, and how does it differ from ASCII?

Unicode is a universal character encoding standard designed to represent a wide range of characters from multiple languages and scripts beyond ASCII’s capabilities. Unlike ASCII’s 7 or 8-bit encoding, Unicode supports encoding using multiple bytes (e.g., UCS-2 with 2 bytes, UCS-4 with 4 bytes) to represent a much larger number of characters.

Why was UCS-4 encoding introduced, and how does it address character representation limitations?

UCS-4 encoding was introduced to expand the number of characters that could be represented, supporting up to 4 billion unique characters with its 4-byte format. This encoding helps accommodate the diverse character sets needed for modern and ancient scripts, ensuring ample space for future expansions.

How does context affect the interpretation of binary sequences in computing?

Context determines how binary sequences are interpreted. For example, the binary sequence '0100 0001' could represent the decimal number 65, the character 'A', or simply be a string of bits depending on its usage in a program, document, or hardware interaction.

What role did ASCII play in early computing, and how did it support information exchange?

ASCII played a crucial role in early computing by providing a standardized way to encode and exchange information between computers, printers, and other devices. It allowed consistent representation of letters, numbers, and symbols, facilitating communication and interoperability in the digital environment.

What challenges do modern character encoding systems face with globalization and diverse languages?

Modern character encoding systems must accommodate the vast variety of languages and scripts worldwide, including those with special characters, accents, and non-Latin alphabets. They also need to support historical and potentially future scripts, making it challenging to balance efficiency and capacity in encoding systems like Unicode.