Data Representation & File Concepts

Data Representation (Digital vs Analog)

Analog Data

• Nature: Continuous and infinite.
• Representation: Represented by continuous physical quantities like voltage, current, sound waves, or temperature.
• Example: A traditional clock with hands, a mercury thermometer, or a vinyl record.
• Disadvantage: Highly susceptible to noise and degradation over time or distance.

Digital Data

• Nature: Discrete and finite.
• Representation: Represented using binary digits (0s and 1s).
• Example: A digital watch, a computer file, or a CD.
• Advantage: Exact replication is possible without any loss of quality. Highly resistant to noise.

Introduction to Data Processing

The Data Processing Cycle

1. Input: Raw data is collected and entered into the system (e.g., typing via a keyboard, scanning a barcode).
2. Processing: The CPU performs operations on the data (sorting, filtering, calculating) based on predefined instructions.
3. Output: The processed data is presented as useful information (e.g., a printed report, an on-screen graph).
4. Storage: The output can be saved for future use.

Difference between Data and Information

• Data: Unorganized, raw facts (e.g., '100', 'John', '50').
• Information: Processed, organized data that has context and meaning (e.g., 'John scored 100 in Math and 50 in Science').

Concepts of Files and Types

File Attributes

• Name: Human-readable string to identify the file.
• Extension: Identifies the file type (e.g., .txt, .mp4).
• Size: How much space it occupies (in Bytes, KB, MB).
• Timestamps: Creation date, last modified date, last accessed date.
• Permissions: Who can read, write, or execute the file.

Common File Types and Extensions

1. Document Files: .txt (Text), .doc / .docx (MS Word), .pdf (Portable Document Format)
2. Spreadsheet Files: .xls / .xlsx (MS Excel), .csv (Comma Separated Values)
3. Image Files: .jpg / .jpeg (Joint Photographic Experts Group), .png (Portable Network Graphics - supports transparency), .gif (Graphics Interchange Format)
4. Audio Files: .mp3 (compressed audio), .wav (uncompressed audio)
5. Video Files: .mp4, .avi, .mkv
6. Executable/System Files: .exe (Windows Executable), .dll (Dynamic Link Library), .bat (Batch file)

File Organization Methods

• Sequential File: Data is stored in a continuous sequence. To read the 10th record, you must read the first 9. (e.g., Magnetic Tapes).
• Direct/Random Access File: Data can be accessed instantly regardless of its position, using a specific key or address. (e.g., Hard Disks, SSDs).
• Indexed Sequential File: Uses an index (like a book's index) to quickly jump to a specific block of data, combining sequential and random access benefits.