Introduction to Computers – Notes Class 11 IP

• Definition: A computer is an advanced electronic device that processes raw data into useful information using a set of instructions called a program.
• Components:
  • Hardware: Physical parts like processor, memory, monitor, keyboard.
  • Software: Programs or instructions that operate the hardware.

Evolution of Computing Devices

1. First Generation (1940-56)
   • Technology: Vacuum tubes
   • Programming: Machine language
   • Examples: ENIAC, EDVAC, EDSAC, UNIVAC-1
2. Second Generation (1956-63)
   • Technology: Transistors replaced vacuum tubes
   • Programming: Assembly and high-level languages (FORTRAN, COBOL)
   • Examples: IBM 1620, IBM 7094, CDC 1604
3. Third Generation (1964-71)
   • Technology: Integrated circuits (ICs)
   • Programming: High-level languages (FORTRAN, COBOL, BASIC)
   • Examples: IBM-360 series, Honeywell-6000
4. Fourth Generation (1972-80)
   • Technology: Microprocessors, LSI & VLSI
   • Programming: High-level languages (C, C++, DBASE)
   • Features: Personal Computers (PCs)
5. Fifth Generation (1980-Present)
   • Technology: Artificial intelligence, parallel processing
   • Examples: Desktop, Laptop, Ultra Book

Components of a Computer System

1. CPU (Central Processing Unit)
   • Parts: Arithmetic Logic Unit (ALU) and Control Unit (CU)
   • Function: Performs calculations, controls operations
2. Memory Unit
   • Primary Memory: Directly accessible (e.g., RAM)
   • Secondary Memory: Long-term storage (e.g., hard drives, USB drives)
3. Input/Output Units
   • Input Devices: Keyboard, mouse, scanner, etc.
   • Output Devices: Monitor, printer, speakers, etc.

Types of Memory

• Bit: Smallest unit, 0 or 1.
• Byte: 8 bits.
• Kilobyte (KB): 1024 bytes.
• Megabyte (MB): 1024 KB.
• Gigabyte (GB): 1024 MB.
• Terabyte (TB): 1024 GB.

Software Types

1. System Software
   • Function: Operates and controls hardware.
   • Examples: Operating systems, compilers, interpreters.
2. Application Software
   • Function: Performs specific tasks.
   • Examples: Microsoft Office, Inventory Management Software.
3. Utility Software
   • Function: Maintains and optimizes computer systems.
   • Examples: Antivirus programs, disk cleanup tools.

Computer Security

• Goals:
  • Confidentiality: Only authorized access.
  • Integrity: Only authorized modifications.
  • Availability: Data accessible when needed.
  • Authentication: Verify identity of users and devices.