Basic Computer Organisation for Class 11: CBSE Easy Notes
Introduction to Computer System
Hey Class 11 CBSE students! A computer system is a smart machine that processes data using hardware and software. It takes input, processes it via the CPU, and gives output—your personal assistant! This is key for CBSE Computer Science.
Why Learn? Vital for programming and practical exams.
Keywords: Computer system Class 11, Basic computer organisation, CBSE Computer Science.
What is Hardware?
Hardware is the physical parts you can touch—like the monitor, keyboard, and CPU. It’s the body of the computer.
Examples: Motherboard, hard disk, mouse.
Tip: Hardware needs software to work!
Example: Hardware: Monitor, CPU, Printer
What is Software?
Software is the set of instructions for hardware. It’s intangible—like apps or operating systems.
Types:
System Software: Manages computer (e.g., Windows).
Application Software: Helps users (e.g., MS Word).
Example:
Software: Linux, Google Chrome
Input Devices in Computer System
Input devices send data to the computer—your way to interact!
Examples:
– Keyboard: Type text.
– Mouse: Click and navigate.
– Scanner: Digitize documents.
Output Devices in Computer System
Output devices show or print results—the final step!
Examples:
– Monitor: Displays data.
– Printer: Prints documents.
– Speakers: Plays sound.
What is CPU (Central Processing Unit)?
The CPU is the computer’s brain. It processes instructions and performs tasks using two main parts: ALU and CU.
Parts:
Arithmetic Logic Unit (ALU): Does math (addition, subtraction) and logic (AND, OR) operations.
Control Unit (CU): Manages and coordinates all CPU activities.
Importance:
ALU: Ensures accurate calculations, crucial for programs like games or spreadsheets.
CU: Keeps everything in sync, making the computer efficient.
Working:
ALU: Takes data, performs operations (e.g., 2 + 3 = 5), and sends results to memory.
CU: Fetches instructions from memory, decodes them, and directs ALU and other units.
Example:
CPU: ALU adds 2 + 3, CU manages the process
Tip: A powerful CPU with good ALU and CU boosts speed!
Memory in Computer Organisation
Memory stores data and instructions with three types:
- Primary Memory:
– Temporary (RAM, ROM).
– Fast but loses data when power off.
– Example: 8GB RAM.
- Cache Memory:
– Ultra-fast, inside CPU.
– Stores frequently used data.
– Example: 256KB Cache.
- Secondary Memory:
– Permanent (HDD, SSD).
– Slower but retains data.
– Example: 1TB Hard Disk.
Units of Memory
Memory is measured in units:
Bit: Smallest unit (0 or 1).
Byte: 8 bits (1 character).
KB (Kilobyte): 1024 bytes.
MB (Megabyte): 1024 KB.
GB (Gigabyte): 1024 MB.
TB (Terabyte): 1024 GB.
PB (Petabyte): 1024 TB.