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
Computers are powerful tools due to several key characteristics
:
- 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)
- First Generation (1940s-1950s): Used Vacuum Tubes. Very large, expensive, and generated immense heat.
- Second Generation (1950s-1960s): Used Transistors. Smaller, faster, cheaper, and more reliable than vacuum tubes.
- Third Generation (1960s-1970s): Used Integrated Circuits (ICs). This allowed for keyboards and monitors.
- Fourth Generation (1970s-Present): Use Microprocessors (thousands of ICs on one chip). Led to the Personal Computer (PC).
- Fifth Generation (Present & Beyond): Focuses on Artificial Intelligence (AI) and quantum computing.
Applications of Computers
Computers are used in almost every field
: education, business, healthcare, entertainment, scientific research, and communication.
1.4 Types of Computers
Computers are categorized by size, power, and purpose
:
- 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
Most digital computers are based on the Von Neumann architecture
. It has five main components:
- Input Unit: Accepts data and instructions from the user (e.g., keyboard).
- Central Processing Unit (CPU): The "brain" of the computer. It processes the data.
- Memory Unit: Stores data and instructions temporarily.
- Output Unit: Presents the processed information to the user (e.g., monitor).
- Storage Unit: Stores data and programs permanently (e.g., hard disk).
1.6 Hardware and Software
Hardware
The physical components of the computer that you can touch and see (e.g., CPU, monitor, keyboard)
.
Software
The set of instructions or programs that tell the hardware what to do
.
- 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.