Unit 1: Introduction to Computer

1.1 Computer Definition

A Computer is an electronic device that takes raw data as input, processes it according to a set of instructions (program), and produces a result (output). It can also store data for future use.

1.2 Characteristics of Computers

• Speed: Can perform billions of operations per second.
• Accuracy: Highly accurate; errors are almost always due to human error (wrong data or instructions).
• Diligence: Can work for long hours without getting tired or losing concentration.
• Versatility: Can perform a wide variety of tasks, from playing music to complex scientific calculations.
• Storage: Can store vast amounts of data in a small space and retrieve it quickly.

1.3 Evolution of Computers & its Applications

Evolution of Computers (Generations)

1. First Generation (1940s-1950s): Used Vacuum Tubes. Very large, expensive, and generated immense heat.
2. Second Generation (1950s-1960s): Used Transistors. Smaller, faster, cheaper, and more reliable than vacuum tubes.
3. Third Generation (1960s-1970s): Used Integrated Circuits (ICs). This allowed for keyboards and monitors.
4. Fourth Generation (1970s-Present): Use Microprocessors (thousands of ICs on one chip). Led to the Personal Computer (PC).
5. Fifth Generation (Present & Beyond): Focuses on Artificial Intelligence (AI) and quantum computing.

Applications of Computers

1.4 Types of Computers

• Supercomputer: The fastest, most powerful, and most expensive. Used for complex scientific tasks (e.g., weather forecasting).
• Mainframe Computer: Large, powerful computers used by big organizations for bulk data processing (e.g., banks, airlines).
• Minicomputer: A mid-sized, multi-user computer.
• Microcomputer: A small, single-user computer. This includes desktops, laptops, and tablets.

1.5 Basic Organization of a Digital Computer

1. Input Unit: Accepts data and instructions from the user (e.g., keyboard).
2. Central Processing Unit (CPU): The "brain" of the computer. It processes the data.
3. Memory Unit: Stores data and instructions temporarily.
4. Output Unit: Presents the processed information to the user (e.g., monitor).
5. Storage Unit: Stores data and programs permanently (e.g., hard disk).

1.6 Hardware and Software

Hardware

Software

• Systems Software: Manages the computer hardware. The most important example is the Operating System (OS).
• Application Software: Helps the user perform a specific task (e.g., Microsoft Word, Google Chrome).
• Utility Software: Performs maintenance tasks to keep the computer running smoothly (e.g., Antivirus, Disk Cleanup).
• Open Source Software: Software whose source code is freely available for anyone to inspect, modify, and enhance (e.g., Linux, Firefox).
• Proprietary Software: Software that is copyrighted and has restrictions on its use and distribution (e.g., Microsoft Windows, Adobe Photoshop).
• Mobile Apps: Applications designed to run on mobile devices like smartphones and tablets.

1.7 CPU, Input, and Output Devices

Central Processing Unit (CPU)

The CPU carries out the instructions of a program. It has two main parts:

• Arithmetic Logic Unit (ALU): Performs all arithmetic (+, -, *, /) and logical (AND, OR, NOT) operations.
• Control Unit (CU): Directs and coordinates all operations within the computer.

Input Devices

Used to get data into the computer

. Examples: Keyboard, Mouse, Scanner, Microphone.

Output Devices

Used to get information out of the computer

. Examples: Monitor, Printer, Speakers, Projector.