Class 11 Computer Science - Computer Overview

What is Computer?

• Computer is an electronic device.
• which manipulates data as per the instruction / commands.
• it is a machine which makes our work easier.
• we can also say it is a high speed calculator.
• It is a data processor which results into an information (Processed data)

Example:

    4 + 2 = 6

    Here 4 and 2 are data and 6 is the information.

Basic Computer Operations:-

A computer works under an IPO cycle.

• Input - data
• Process - Calculation
• Output - Information

Command / Instructions are given to computer as programs, which are the instructions converted into Computer understandable language (Machine Language).

Characteristics of a Computer:-

• Speed
• Accuracy
• Storage Capacity
• Reliability
• Flexibility

Limitations of a Computer:-

• Reliability of programs - If programs are wrong then output will also be wrong.
• No thinking power
• Computers are Emotionless.

Functional Unit of Computer:-

Functional Unit of Computer

Block Diagram of Computer:-

Block Diagram of Computer

Input Devices:-

• Keyboard
• Mouse - Wireless mouse, mechanical mouse, Optical mouse
• Trackball
• Joystick
• Light pen
• Touch screen
• Barcode Reader
• Optical mark reader (OMR)
• Optical character Recognition (OCR)
• Magnetic ink character recognition (MICR)
• Smart card reader
• Biometric Sensor
• Scanner
• Microphone
• Web camera

Output Devices:-

• Monitor
• Printer
• Plotter
• Speaker
• Headphone
• Projector

CPU:-

Arithmetic Logic Unit (ALU):-

• This ALU does the calculation on the computer.
• Calculations are of two types:-
  • Arithmetic (+ - * / %)
  • Logical

Control Unit:-

• It helps in Controlling Devices.

Memory Unit:-

• It is used as the storage.

Memory Hierarchy:-

Memory Hierarchy

Classification of Memory:-

Classification of Memory

Primary Memory:-

• Used for processing
• This memory unit directly communicates with CPU
• Fast but low storage
• Have two types:-
  • RAM
  • ROM

Secondary Memory:-

• Used for storing data for long period of time.
• Compared to Primary memory, secondary memory costs less.
• Using secondary we can transfer data from one device to another device easily.

Eg:

    USB, SDD, HDD, CD Disk, etc.