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1. Class 9 Computer Science
Chapter 1: Basics of Computer
Devices

2. What is a Computer?
• • A computer is an electronic device that
processes data.
• • It works on the Input-Process-Output (IPO)
cycle.
• • It performs tasks based on a set of
instructions (programs).

3. IPO Cycle
• 1. Input – Data is entered using input devices.
• 2. Process – Data is processed by the CPU.
• 3. Output – Result is displayed via output
devices.
• 4. Storage – Data can be stored for later use.

4. Input Devices
• • Devices that enter data into the computer:
• - Keyboard
• - Mouse
• - Scanner
• - Microphone
• - Webcam
• - Touchscreen

5. Output Devices
• • Devices that display or present processed
data:
• - Monitor
• - Printer
• - Speakers
• - Headphones
• - Projector

6. Storage Devices
• • Devices used to store data:
• - RAM, ROM (Primary)
• - HDD, SSD, USB, CD/DVD (Secondary)

7. CPU and Its Units
• • CPU: Central Processing Unit - brain of the
computer.
• • ALU – Performs calculations.
• • CU – Controls operations.
• • Registers – Temporary memory inside CPU.

8. Hardware vs Software
• • Hardware: Physical parts (e.g., monitor,
keyboard).
• • Software: Programs/instructions (e.g., MS
Word, Windows).
• • Types of Software: System and Application
software.

9. Characteristics of Computer
• • Speed
• • Accuracy
• • Automation
• • Diligence
• • Versatility
• • Storage

10. Summary
• • Computer = Input + Process + Output +
Storage
• • Components = Input, Output, Processing,
Storage
• • Hardware vs Software
• • CPU = ALU + CU + Registers