BCA-1 [Emerging Information Technologies -Unit-1]

Introduction to Computers

The term "computer" originates from "compute," meaning to calculate.
A computer is an electronic device that performs calculations and controls operations expressed in logical or numerical terms.
Definition: A device that receives data as input, processes it, and produces information as output.

Speed: Computers process data at millions of instructions per second (measured in Megahertz).
Accuracy: High accuracy, errors due to faulty instructions can be minimized.
Reliability: Operate without human intervention, with built-in diagnostic capabilities.
Storage Capability: Can store large amounts of data on devices like CD-ROMs and hard disks (e.g., 700MB in CD-ROM vs. 80GB in hard disk).
Versatility: Perform multiple tasks simultaneously by changing the program.
Diligence: Do not suffer from tiredness; perform tasks consistently at the same accuracy.

A computer system consists of hardware, components, peripherals, and data communication equipment.
Key Components:
1. Central Processing Unit (CPU): Processes instructions and data.
  - Arithmetic Logic Unit (ALU): Performs arithmetic and logical operations.
  - Control Unit: Ensures correct operation sequence and program execution.
  - Memory Unit: Temporarily stores data and instructions.
2. Input Unit: Accepts instructions and data using devices like keyboards and mice.
3. Output Unit: Communicates results to the user through devices like monitors and printers.

Keyboard: Converts keystrokes into machine-readable output.
Mouse: Controls the cursor and interacts with the display.
- Variants: One-button, two-button, or multi-button.
Bar Code Readers: Use bar codes to input data quickly.
Optical Character Readers (OCR): Convert printed text to machine-readable text.
Magnetic Ink Character Recognition (MICR): Used in banking to read checks.

Monitors: Display information using pixels, with resolution measured in dots per inch (dpi).
Printers: Include impact (dot-matrix) and non-impact (laser, ink-jet) types.
Plotters: Create high-resolution drawings directly from vector files.
Sound and Graphics: Includes digital sound output and graphical displays.

Random Access Memory (RAM): Temporary storage for active processes, volatile.
Read Only Memory (ROM): Permanent storage for firmware, non-volatile.
- Types of RAM:
  - Static RAM (SRAM): Fast, does not need refreshing, used for cache memory.
  - Dynamic RAM (DRAM): Slower, needs refreshing.
- Types of ROM:
  - Masked ROM: Hard-wired, cannot be changed.
  - Programmable ROM (PROM): Can be programmed once.
  - Erasable Programmable ROM (EPROM): Can be erased with UV light.
  - Electrically Erasable Programmable ROM (EEPROM): Can be erased and reprogrammed electronically.

Provides backup storage; examples include hard disks, magnetic tapes, and optical disks.
Storage devices retain information even when the computer is off, providing much larger capacity than primary memory.
- Magnetic Tapes: Sequential access, divided into tracks.
- Magnetic Disks: Random access, formatted into sectors and tracks.
- Optical Disks: Used for storing data in read-only or writeable formats (CDs, DVDs).

First Generation (1940-56): Vacuum tubes, large and expensive.
Second Generation (1956-63): Transistors reduced size and costs, improved reliability.
Third Generation (1964-early 1970s): Integrated circuits made computers smaller and more efficient.
Fourth Generation (early 1970s-present): Microprocessors led to powerful, compact computers.
Fifth Generation (Present and Beyond): Aimed at Artificial Intelligence, advanced natural language processing.