Understand what a computer is, how it evolved through generations, its types, components, and how data moves from input to output.
Definition: A computer is an electronic device that accepts data as input, processes it according to a set of instructions (program), stores the results, and produces output in a meaningful form.
The word "Computer" comes from the Latin word "computare", meaning "to calculate." Early computers were mechanical calculating devices. Today, computers are powerful digital machines that handle a wide variety of tasks — from browsing the internet to controlling satellites.
Raw data fed into the computer through devices like keyboard, mouse, scanner.
The CPU performs arithmetic and logical operations on the input data.
Processed and raw data is stored in primary or secondary memory for later use.
Results displayed or printed through devices like monitor, printer, or speakers.
Fig 1.1 — Basic Block Diagram of a Computer System
The ALU (Arithmetic Logic Unit) performs calculations and comparisons. The CU (Control Unit) directs the operations of the processor. Registers are tiny, super-fast storage locations inside the CPU used during processing.
Computers perform millions of instructions per second (MIPS). They work far faster than any human being.
Computers produce highly accurate results. Errors occur only due to incorrect data or faulty programs.
Computers can store vast amounts of data in a small physical space and retrieve it instantly.
The same computer can be used for typing, calculations, graphics, video, and thousands of other tasks.
A computer never gets tired or loses concentration. It can perform the same task repeatedly without error.
Once a program is loaded, a computer executes instructions automatically without continuous human intervention.
Computers have evolved through five generations, each marked by significant changes in technology, speed, size, and cost.
Used vacuum tubes for circuitry and magnetic drums for memory. Very large, expensive, and generated enormous heat. Used machine language only. Example: ENIAC, UNIVAC.
Replaced vacuum tubes with transistors — smaller, faster, cheaper, and more reliable. Assembly language introduced. Example: IBM 1401, Honeywell 400.
ICs replaced transistors, placing multiple transistors on a single chip. Keyboards and monitors introduced. High-level languages used. Example: IBM 360, PDP-8.
Entire CPU placed on a single chip (microprocessor). Personal computers (PCs) became common. GUI, mouse, and networks emerged. Example: Intel 4004, Apple Macintosh, IBM PC.
Based on Artificial Intelligence (AI). Computers that can learn, reason, and respond to natural language. Voice recognition, robotics, and parallel processing. Example: IBM Watson, modern AI systems.
A. Based on Working Principle
| Type | Description | Example |
|---|---|---|
| Analog | Works with continuous data (voltage, temperature). Gives approximate results. | Speedometer, thermometer |
| Digital | Works with discrete data (0 and 1). Gives precise results. | Desktop PC, Laptop |
| Hybrid | Combines features of both analog and digital computers. | Hospital ICU monitors |
B. Based on Size
| Type | Size / Speed | Usage |
|---|---|---|
| Supercomputer | Largest, fastest | Weather forecasting, nuclear research, space exploration |
| Mainframe | Very large, very fast | Banks, insurance companies, large organizations |
| Mini Computer | Medium size | Universities, hospitals, mid-size businesses |
| Workstation | High-performance desktop | Engineering design (CAD/CAM), scientific research |
| Micro (PC) | Small, affordable | Home, office, education |
| Desktop | Fixed, non-portable | Office work, gaming |
| Laptop | Portable, battery-powered | Mobile professionals, students |
| Palmtop | Pocket-sized | Personal organizers, early PDAs |
C. Based on Processor Type
8-bit/16-bit processor. Early IBM PCs. Intel 8086/8088.
32-bit processor. IBM AT. Intel 80286, 80386, 80486.
64-bit processors. Intel Core i3, i5, i7. Modern systems.
Physical, tangible parts of a computer you can touch — monitor, keyboard, mouse, CPU, RAM, HDD, printer. Hardware is useless without software.
Set of instructions (programs) that tell the hardware what to do. Examples: Windows OS, MS Word, Google Chrome. Software is divided into System Software and Application Software.
Memory Units: Bit → Nibble (4 bits) → Byte (8 bits) → KB (1024 B) → MB (1024 KB) → GB (1024 MB) → TB (1024 GB) → PB (1024 TB)
The Central Processing Unit (CPU) is the brain of the computer. It is housed on the motherboard and contains the processor chip. The CPU reads instructions from memory and executes them.
| Component | Description |
|---|---|
| Motherboard | Main circuit board that connects all components — CPU, RAM, storage, ports. |
| Processor | The chip that executes instructions. Speed measured in GHz. E.g., Intel Core i7 @ 3.6 GHz. |
| Hard Disk (HDD/SSD) | Stores the operating system, software, and user data permanently. |
| RAM | Temporary working memory used while running programs. |
| ROM | Contains BIOS — firmware that starts the system during booting. |
| SMPS | Switched Mode Power Supply. Converts AC mains power to DC voltages needed by components. |
| Graphics Card | Renders images, video, and animations for the monitor. Has its own GPU and VRAM. |
| Sound Card | Processes audio input/output. Enables speakers and microphone. |
| Network Card (NIC) | Enables network/internet connectivity. Can be wired (Ethernet) or wireless (Wi-Fi). |
| Modem | Modulates/demodulates signals to connect to the internet via telephone or cable lines. |
Primary input device. QWERTY layout for English. Tamil99 layout for Tamil.
Pointing device for GUI interaction. Left click, right click, scroll wheel.
Converts physical documents and images into digital format. Flatbed is most common.
Captures still images and videos digitally. Can transfer files via USB or Wi-Fi.
Input device for games and simulations. Controls movement in multiple directions.
Drawing surface with a stylus pen. Used by designers and artists.
Primary output device. LCD, LED, and OLED types. Resolution measured in pixels (e.g., 1920×1080 Full HD).
Produces hard copies on paper. Types: Inkjet, Laser, Dot Matrix, Thermal.
Produces large-format drawings (engineering diagrams, maps). Uses pens or inkjet heads.
| Port | Speed / Type | Used For |
|---|---|---|
| Serial Port (COM) | Slow, one bit at a time | Old mice, modems, early devices |
| Parallel Port (LPT) | Multiple bits simultaneously | Old printers and scanners |
| USB (Universal Serial Bus) | USB 2.0 (480 Mbps), USB 3.0 (5 Gbps) | Pen drives, keyboard, mouse, phone charging, printers |
| HDMI / VGA | Video signal | Connecting monitor, projector, TV |
| Ethernet (RJ-45) | 10/100/1000 Mbps | Wired internet connection |
| Audio Jack (3.5mm) | Analog audio | Headphones, speakers, microphone |
Installing Peripherals: When connecting a scanner or printer, insert the device's driver CD or use Windows plug-and-play. For a monitor, connect the VGA/HDMI cable to the graphics card port. Keyboard and mouse connect via USB or PS/2 ports at the rear of the system unit.
Patient records, diagnostic imaging, robotic surgery, hospital management.
e-Learning, digital libraries, online examinations, simulation labs.
Online banking, ATM operations, fraud detection, loan processing.
CAD/CAM design, robotics, inventory management, supply chain.
Email, video conferencing, social media, VoIP calling.
e-Governance, e-Office, tax filing, citizen services portals.
Movies, music, gaming, streaming services, animation.
Weather forecasting, space exploration, genome sequencing, simulations.
1. The brain of a computer is called the:
2. Which generation of computers used vacuum tubes?
3. RAM stands for:
4. Which of the following is an Output device?
5. 1 Gigabyte (GB) = ?
6. Which type of computer works with continuous data like voltage or temperature?
7. Match: SMPS stands for:
8. True or False: SSD (Solid State Drive) has no moving parts.