✅ CHAPTER 1:Introduction to
Computers
(Evolution of Computers excluded as your teacher said)
🔹 Learning Objectives
In this chapter you learn:
● What is a computer
● What is data processing
● Characteristics of computers
● Computer generations
● Features of each generation
🔹 What is a Computer?
The word computer comes from the word compute, which means to calculate.
A computer is an electronic device that:
● Performs arithmetic operations at very high speed
● Stores data
● Processes data
● Retrieves data whenever needed
Because it processes data, a computer is also called a data processor.
🔹 Data Processing
Data processing means processing data using a computer.
Steps of data processing:
1. Capture data (Input)
2. Manipulate data (Processing)
3. Produce output (Information)
👉 Data = raw facts
👉 Information = processed data
Example:
Marks list = data
Average marks = information
🔹 Characteristics of Computers
1️⃣ Automatic
Once a program is given, the computer works automatically without human help.
2️⃣ Speed
Computers are extremely fast.
Speed is measured in:
● Microseconds (10⁻⁶)
● Nanoseconds (10⁻⁹)
● Picoseconds (10⁻¹²)
3️⃣ Accuracy
Computers are highly accurate.
Errors usually happen because:
● Wrong input data
● Wrong program
This is called GIGO (Garbage In, Garbage Out).
4️⃣ Diligence
A computer never gets tired or bored.
It can work for hours continuously without making mistakes.
5️⃣ Versatility
A computer can perform many different types of tasks:
● Banking
● Education
● Designing
● Gaming
● Scientific calculations
6️⃣ Power of Remembering
A computer can store a huge amount of data and recall it whenever needed.
It forgets data only when instructed.
7️⃣ No I.Q.
A computer cannot think or make decisions on its own.
It only follows instructions.
8️⃣ No Feelings
Computers do not have emotions.
They work based only on logic and instructions.
🔹 Computer Generations
“Generation” means a stage of technological development.
There are five generations of computers.
🥇 First Generation (1942–1955)
Hardware:
● Vacuum tubes
● Electromagnetic relay memory
● Punched cards
Software:
● Machine language
● Assembly language
● Stored program concept
Features:
● Very large size
● Generated a lot of heat
● Not reliable
● Very expensive
● Mostly used for scientific applications
🥈 Second Generation (1955–1964)
Hardware:
● Transistors
● Magnetic core memory
● Magnetic tapes and disks
Software:
● Batch operating system
● High-level programming languages
Features:
● Smaller and faster
● More reliable
● Easier to program
● Still costly
🥉 Third Generation (1964–1975)
Hardware:
● Integrated Circuits (ICs)
● Larger memory
● Larger capacity disks
Software:
● Time-sharing operating system
● Standard high-level languages
● Software separated from hardware
Features:
● Smaller
● Cheaper
● More reliable
● Easier to upgrade
● Used for scientific and commercial applications
🏅 Fourth Generation (1975–1989)
Hardware:
● VLSI technology
● Microprocessors
● Semiconductor memory
● Hard disks
Software:
● GUI-based operating systems
● UNIX with C language
● Object-oriented programming
Features:
● Personal computers (PCs)
● Supercomputers
● Network-based systems
● Affordable and user-friendly
🏆 Fifth Generation (1989–Present)
Hardware:
● ULSI technology
● RAID hard disks
● Optical disks
Software:
● Java
● World Wide Web
● Multimedia applications
● Distributed operating systems
Features:
● Portable computers
● Internet
● Powerful servers
● Cluster computing
● Very advanced supercomputers
✅ CHAPTER 2 – Basic Computer
Organization
🔹 Learning Objectives
You will learn about:
● Basic operations of a computer
● Organization of a computer system
● Input unit
● Output unit
● Storage unit
● Types of storage
● ALU
● CU
● CPU
● System concept
🔹 Five Basic Operations of a Computer
System
1. Inputting – Entering data into the computer
2. Storing – Saving data and instructions
3. Processing – Performing arithmetic or logical operations
4. Outputting – Producing useful results
5. Controlling – Directing all operations
🔹 Basic Organization of a Computer
Main units:
● Input Unit
● Output Unit
● Storage Unit
● Central Processing Unit (CPU)
🔹 Input Unit
Functions:
1. Accepts data and instructions
2. Converts them into computer-readable form
3. Sends them to the computer for processing
Examples: Keyboard, Mouse
🔹 Output Unit
Functions:
1. Accepts processed results
2. Converts them into human-readable form
3. Produces output
Examples: Monitor, Printer
🔹 Storage Unit
Stores:
● Data
● Instructions
● Intermediate results
● Final results
🔹 Two Types of Storage
🔸 Primary Storage
● Holds running programs
● Fast
● Small capacity
● Expensive
● Volatile (loses data when power is off)
🔸 Secondary Storage
● Stores programs and data permanently
● Slower
● Large capacity
● Cheaper
● Non-volatile
🔹 Arithmetic Logic Unit (ALU)
Performs:
● Arithmetic operations (add, subtract, multiply, divide)
● Logical operations (>, <, =)
🔹 Control Unit (CU)
● Controls all operations of the computer
● Directs other units
🔹 Central Processing Unit (CPU)
CPU = ALU + CU
It is the brain of the computer.
🔹 System Concept
A system has:
1. More than one element
2. Elements that are logically related
3. Controlled operation to achieve a goal
A computer is a system because:
Input + Output + Storage + CPU work together.
✅ CHAPTER 9 – Input and Output
Devices
🔹 Introduction
A computer works with the help of Input and Output devices.
● Input devices → Used to give data and instructions to the computer.
● Output devices → Used to get results from the computer.
Without input and output devices, a computer cannot communicate with users.
🟢 INPUT DEVICES
🔹 What is an Input Device?
An input device is a hardware device that is used to enter data and instructions into the
computer.
It converts human-readable data into machine-readable form (binary).
🔹 Classification of Input Devices
Input devices are mainly divided into:
1. Keyboard Devices
2. Pointing Devices
3. Scanning Devices
4. Digitizing Devices
5. Electronic Input Devices
6. Voice Input Devices
1️⃣ Keyboard
The keyboard is the most common input device.
It is used to type:
● Letters
● Numbers
● Symbols
● Commands
🔸 Types of Keys
1. Alphanumeric Keys
A–Z, 0–9
2. Function Keys
F1 to F12
3. Control Keys
Ctrl, Alt, Shift
4. Special Purpose Keys
Enter, Delete, Home, End
5. Arrow Keys
Used to move cursor
2️⃣ Pointing Devices
Used to point, select, and move objects on screen.
🔸 Mouse
Most common pointing device.
Functions:
● Click
● Double click
● Drag and drop
● Scroll
Types of Mouse:
● Mechanical mouse
● Optical mouse
● Wireless mouse
🔸 Trackball
Like an upside-down mouse.
You rotate a ball to move the pointer.
🔸 Touchpad
Used in laptops.
Move finger to control cursor.
🔸 Light Pen
Used to draw directly on screen.
🔸 Joystick
Used mainly for games.
Controls movement in different directions.
3️⃣ Scanning Devices
Used to scan text or images into computer.
🔸 Scanner
Converts paper documents into digital form.
Types:
● Flatbed scanner
● Handheld scanner
● Drum scanner
🔸 OCR (Optical Character Recognition)
Converts printed text into editable text.
Example:
Printed book → Editable Word file
🔸 OMR (Optical Mark Recognition)
Reads marked answers.
Example:
MCQ exam answer sheet
🔸 MICR (Magnetic Ink Character Recognition)
Used in banks to read cheques.
🔸 BCR (Bar Code Reader)
Reads barcodes.
Used in:
● Supermarkets
● Shopping malls
4️⃣ Digitizing Devices
🔸 Digitizer
Converts drawings into digital form.
Used in:
● Engineering design
● Architecture
5️⃣ Electronic Card Reader
Reads information from:
● ATM cards
● Smart cards
6️⃣ Voice Input Devices
🔸 Microphone
Used to input voice into computer.
Voice is converted into digital signals.
Used in:
● Online meetings
● Voice typing
● AI assistants
🟢 OUTPUT DEVICES
🔹 What is an Output Device?
An output device is a hardware device that gives processed information to the user.
It converts machine-readable data into human-readable form.
🔹 Classification of Output Devices
1. Soft Copy Output Devices
2. Hard Copy Output Devices
1️⃣ Soft Copy Output Devices
Output displayed temporarily.
🔸 Monitor (VDU – Visual Display Unit)
Most common output device.
Displays:
● Text
● Images
● Videos
Types of Monitors:
1. CRT (Cathode Ray Tube)
Old and bulky
2. LCD (Liquid Crystal Display)
Flat and lightweight
3. LED (Light Emitting Diode)
Better brightness and power saving
4. Touch Screen
Works as both input and output device
2️⃣ Hard Copy Output Devices
Produce permanent output on paper.
🔸 Printer
Used to print documents.
Printers are of Two Types:
🖨️ Impact Printers
They print by striking ribbon on paper.
Examples:
🔹 Dot Matrix Printer
● Prints using dots
● Noisy
● Used for bills
🔹 Daisy Wheel Printer
● Prints character by character
● Slow
🖨️ Non-Impact Printers
They print without striking paper.
Examples:
🔹 Inkjet Printer
● Uses liquid ink
● Good for color printing
🔹 Laser Printer
● Uses laser technology
● Fast
● High quality
🔸 Plotter
Used to print large drawings.
Used in:
● Engineering
● Architecture
Types:
● Drum plotter
● Flatbed plotter
🔹 Difference Between Input and Output
Devices
Input Device
Output Device
Sends data to computer
Receives data from computer
Converts to machine
language
Converts to human-readable
form
Example: Keyboard
Example: Monitor
🔥 Important Points for Exam
● Definition of input device
● Definition of output device
● Types of printers (Impact vs Non-impact)
● Difference between OCR, OMR, MICR
● Types of monitors
● Difference between soft copy & hard copy output
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