Encoding Schemes Class 11 CBSE Computer Science: ASCII, ISCII and Unicode (UTF-8 & UTF-32)
Class 11 · Computer Science
Encoding Schemes (CBSE Class 11 Computer Science)
Computers can understand only binary digits (0 and 1). However, users communicate using letters, numbers, symbols, and characters from different languages. An Encoding Scheme is used to represent these characters in binary form so that computers can store, process, and exchange information correctly.
Learning Objectives
- Understand character encoding.
- Learn the need for encoding schemes.
- Study ASCII.
- Study ISCII.
- Study Unicode.
- Understand UTF-8 and UTF-32.
What is an Encoding Scheme?
An Encoding Scheme is a standard method used to assign a unique binary code to every character, number, symbol, or special character.
Why Do We Need Encoding Schemes?
Computers understand only binary (0 and 1). When we type a character such as A or ₹, it must be converted into binary before the computer can process it.
Benefits
- Stores text in digital form.
- Enables communication between different computer systems.
- Supports multiple languages.
- Ensures consistent representation of characters.
- Facilitates data sharing across platforms.
Working of Character Encoding
Character Typed
│
▼
Encoding Scheme
│
▼
Binary Code
│
▼
Stored in Computer Memory
Types of Encoding Schemes
- ASCII
- ISCII
- Unicode
ASCII (American Standard Code for Information Interchange)
ASCII is one of the earliest and most widely used character encoding standards. It was developed to represent English letters, numbers, punctuation marks, and control characters.
Features
- Uses 7 bits.
- Represents 128 characters (0–127).
- Supports English language only.
- Includes alphabets, digits, symbols, and control characters.
Examples of ASCII Codes
| Character | ASCII Value |
|---|---|
| A | 65 |
| B | 66 |
| a | 97 |
| 0 | 48 |
| Space | 32 |
Limitations of ASCII
- Supports only English characters.
- Cannot represent Indian languages.
- Cannot represent many international symbols.
- Limited to 128 characters.
ISCII (Indian Script Code for Information Interchange)
ISCII was developed in India to support Indian languages that could not be represented using ASCII.
Features
- Uses 8-bit encoding.
- Supports many Indian scripts.
- Can represent languages such as Hindi, Sanskrit, Bengali, Tamil, Telugu, Gujarati, Punjabi, Kannada, Malayalam, Marathi, and Odia.
- Based on the Indian Standard IS 13194.
Need for ISCII
ASCII was designed mainly for English. India has many official languages with different scripts. ISCII was developed to encode these scripts efficiently.
Unicode
Unicode is an international character encoding standard that assigns a unique code to every character from almost every language and writing system in the world.
Features of Unicode
- Universal character encoding standard.
- Supports almost all world languages.
- Provides a unique code point for each character.
- Supports mathematical symbols, currency symbols, and emojis.
- Ensures compatibility across different platforms.
Examples of Unicode Characters
| Character | Unicode |
|---|---|
| A | U+0041 |
| ₹ | U+20B9 |
| अ | U+0905 |
| ? | U+1F60A |
Unicode Transformation Formats (UTF)
Unicode characters are stored using different encoding formats called Unicode Transformation Formats (UTF).
The CBSE syllabus includes:
- UTF-8
- UTF-32
UTF-8
UTF-8 is the most widely used Unicode encoding format on the Internet.
Features
- Uses 1 to 4 bytes per character.
- Compatible with ASCII.
- Saves storage space for English text.
- Supports all Unicode characters.
- Widely used in websites and web applications.
UTF-32
UTF-32 uses a fixed length of 4 bytes (32 bits) for every character.
Features
- Every character occupies exactly 4 bytes.
- Easy to process because all characters have equal length.
- Consumes more memory than UTF-8.
- Used where fixed-width encoding is preferred.
Comparison of ASCII, ISCII and Unicode
| Feature | ASCII | ISCII | Unicode |
|---|---|---|---|
| Bits Used | 7 | 8 | Variable (UTF-8) / 32 bits (UTF-32) |
| Characters Supported | 128 | Indian Scripts | Almost All Languages |
| Supports English | Yes | Yes | Yes |
| Supports Indian Languages | No | Yes | Yes |
| Supports Emojis | No | No | Yes |
UTF-8 vs UTF-32
| UTF-8 | UTF-32 |
|---|---|
| 1–4 bytes per character. | Always 4 bytes per character. |
| Memory efficient. | Consumes more memory. |
| Most commonly used on the Internet. | Less commonly used. |
| Compatible with ASCII. | Not ASCII-compatible in storage format. |
Real-Life Example
Imagine every student in a school is assigned a unique roll number.
- ASCII is like assigning roll numbers only to one class.
- ISCII is like assigning roll numbers to all classes in one school (Indian languages).
- Unicode is like assigning unique roll numbers to students in schools all over the world, ensuring no two students have the same number.
Common Errors
- Confusing ASCII with Unicode.
- Assuming ASCII supports all languages.
- Thinking UTF-8 and Unicode are different standards.
- Believing UTF-32 is more popular than UTF-8.
- Confusing ISCII with ASCII.
Exam Tips
- Remember that ASCII uses 7 bits and supports 128 characters.
- ISCII was developed to support Indian languages.
- Unicode is the universal character encoding standard.
- UTF-8 is the most widely used Unicode encoding format.
- UTF-32 uses a fixed length of 4 bytes for each character.
- Practice comparison tables between ASCII, ISCII and Unicode.
Frequently Asked Questions (FAQs)
1. Why is an encoding scheme required?
An encoding scheme converts characters into binary so that computers can store, process, and exchange data.
2. What is the limitation of ASCII?
ASCII supports only English characters and has a limited character set of 128 characters.
3. Why was ISCII developed?
ISCII was developed to support Indian languages and scripts.
4. What is Unicode?
Unicode is an international standard that assigns a unique code to characters from almost all languages and symbols.
5. Which Unicode format is most commonly used on the Internet?
UTF-8 is the most widely used Unicode encoding format.
Summary
- Encoding schemes represent characters using binary codes.
- ASCII is a 7-bit encoding standard that supports English characters.
- ISCII is an 8-bit encoding scheme designed for Indian languages.
- Unicode is a universal character encoding standard supporting almost all languages.
- UTF-8 is memory efficient and widely used on the Internet.
- UTF-32 uses a fixed 4-byte representation for every character.
- Character encoding enables computers to process and exchange text accurately across different platforms.