Data Representation: Text, Sound And Images: Understand How And Why A Computer Represents Text And The Use Of Character Sets, Including American Standard Code For Information Interchange (Ascii) And Unicode (Copy)
| Concept | Computer Representation Of Text |
|---|---|
| Why Text Is Encoded | Computers only understand binary (0s and 1s) |
| Method | Each character is assigned a unique binary code |
| Result | Text becomes machine-readable and storable |
| Unit | Characters stored as bytes or multiple bytes |
| Character Set | Meaning |
|---|---|
| Definition | A mapping between characters and binary numbers |
| Purpose | Ensures consistent text interpretation |
| Examples | ASCII, Unicode |
| ASCII | Key Facts |
|---|---|
| Full Name | American Standard Code For Information Interchange |
| Bits Used | 7-bit (original), 8-bit (extended) |
| Characters | 128 (standard), 256 (extended) |
| Coverage | English letters, digits, symbols, control characters |
| ASCII Examples | Decimal | Binary |
|---|---|---|
| A | 65 | 01000001 |
| a | 97 | 01100001 |
| 0 | 48 | 00110000 |
| Space | 32 | 00100000 |
Written and Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total A Grades, 7 Distinctions and 11 World Records For Educate A Change O Level And IGCSE Computer Science Full Scale Course
| Limitations Of ASCII | Explanation |
|---|---|
| Language Support | Cannot represent most world languages |
| Character Count | Too limited for modern computing |
| Symbols | Insufficient for emojis and scripts |
| Unicode | Key Facts |
|---|---|
| Purpose | Universal character representation |
| Coverage | All major languages and symbols |
| Characters | Over 1 million possible codes |
| Compatibility | Includes ASCII values |
| Unicode Encoding Forms | Bits Used |
|---|---|
| UTF-8 | 8 to 32 bits (most common) |
| UTF-16 | 16 or 32 bits |
| UTF-32 | 32 bits |
Written and Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total A Grades, 7 Distinctions and 11 World Records For Educate A Change O Level And IGCSE Computer Science Full Scale Course
| ASCII vs Unicode | ASCII | Unicode |
|---|---|---|
| Languages | English only | All languages |
| Size | Small | Variable |
| Modern Use | Limited | Global standard |
| Emoji Support | No | Yes |
| Why Unicode Is Needed | Reason |
|---|---|
| Global Computing | Supports multilingual systems |
| Internet Use | Enables worldwide text sharing |
| Modern Software | Required for internationalisation |
Written and Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total A Grades, 7 Distinctions and 11 World Records For Educate A Change O Level And IGCSE Computer Science Full Scale Course
| Common Examiner Traps | How To Avoid |
|---|---|
| Saying ASCII supports all languages | State its limitations |
| Mixing encoding and character set | Character set ≠encoding |
| Forgetting ASCII inside Unicode | Mention compatibility |
| Not giving examples | Quote ASCII values |
| One-Line Summary | Exam-Perfect Statement |
|---|---|
| Text Representation | Characters mapped to binary codes |
| ASCII | Early, limited character set |
| Unicode | Universal standard for text |
Written and Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total A Grades, 7 Distinctions and 11 World Records For Educate A Change O Level And IGCSE Computer Science Full Scale Course