Chapter 1: Computer and its Components

Class: X | Subject: Information and Computer Technology

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Key Concepts

Data vs Information

• Data is a collection of unprocessed facts, figures, and symbols (e.g., Ram, age, 32, years, old).
• Information is the processed form of data that is organised, meaningful, and useful (e.g., "Ram is 32 years old").

Hardware and Software

• Hardware: Any physical component of the computer that can be seen and touched.
• Software: The instruction set that tells the computer how to perform tasks. It is intangible.

Hardware Components

I. Input Devices, accept data from the user and convert it from human-readable to machine-readable form., Keyboard, Mouse, Microphone, Scanner, Trackball, Joystick, Graphics Tablet, Digital Camera

II. Output Devices, display results in human-readable form., Monitor (VDU), LCD, Printers, Plotters, Speakers

III. Storage Devices, save and retrieve data., Floppy Disk (1.44 MB, now obsolete), Hard Disk (metal disk, stores tens to hundreds of GB), CD-ROM (read-only or read-write; CD-R holds 700 MB once, CD-RW is rewritable), DVD (Digital Versatile Disc, 4.7 GB, double-sided dual layer), Blu-Ray Disc (25+ GB single layer; 13 hours video single layer, 20+ hours double layer), USB / Pen Drive (portable, connects via USB port), Memory Card / Flash Memory Card (used in cameras, phones, game consoles)

CPU (Central Processing Unit), The processor unit is the heart of the computer system.

• ALU (Arithmetic and Logic Unit): Executes arithmetic and logical operations.
• Control Unit (CU): Acts as the nerve centre, sending control signals to all other units., The CU and ALU are much faster than connected external devices, enabling a single processor to control many peripherals.

Memory

Primary Memory, fast, used for active program execution:

• RAM (Random Access Memory): Volatile; data disappears when power is off. Can be read and written.
• ROM (Read Only Memory): Non-volatile; permanently built in at production. Contains boot-up instructions. Read-only.

Secondary Memory (Auxiliary Memory), permanent storage, cheaper than primary memory:

• Hard Disk, DVD, USB, etc., Needed because RAM is volatile and primary storage is expensive.

Units of Memory

Unit	Equivalent
1 nibble	4 bits
1 byte	8 bits
1 KB	1024 bytes
1 MB	1024 KB
1 GB	1024 MB
1 TB	1024 GB
1 PB	1024 TB

• Computers work in the binary number system (base 2), using only digits 0 and 1., A single 0 or 1 is called a bit; a sequence of bits makes a byte.

Software Types

Application Software, directs the computer to carry out specific tasks:

• General Purpose: Word Processors (Writer, MS Word), Spreadsheets (Calc, Excel), Presentation (Impress, PowerPoint), Desktop Publishing (GIMP, Photoshop, CorelDraw)
• Customised / Tailored: Created for specific user needs (e.g., Tally, QuickBooks)

System Software, interface between user/applications and hardware:

• Operating System (OS): Manages all programs, file storage, hardware coordination. Frees user from direct hardware interaction.
• Utility Software: Performs housekeeping functions:
• Text Editors (WordPad, Notepad)
• Compression Utilities
• Disk Fragmentation utility
• Scan Disk utility
• Encryption/Decryption utility

Computer Characteristics

• Speed: Computes much faster than humans.
• Accuracy: Produces accurate results if input is valid (GIGO, Garbage In Garbage Out).
• No IQ: Has no intelligence of its own; performs exactly as instructed.
• Diligence: Performs tasks repeatedly without tiring, with consistent results.
• Data Storage: Can store huge quantities of data over long periods.
• No Heuristics: Never learns from past experiences.

Generations of Computers

Generation	Period	Technology	Examples
I	1945-55	Vacuum tubes, assembly language	ENIAC, EDSAC, EDVAC, UNIVAC
II	1955-65	Transistors, FORTRAN, COBOL	IBM 7030, Honeywell 400
III	1965-75	SSI/MSI ICs, microprogramming, OS software	IBM System 360, PDP-8
IV	1975-89	Microprocessors, CRT, LAN/WAN, C, UNIX	Intel 8088/80286/80386, Apple II, CRAY
V	1989-present	Parallel processing, portable notebooks, JAVA, nanotechnology	Pentium PCs, PARAM 10000

Categories of Computers

By functioning:

• Analog: Uses continuously variable physical quantities to represent data.
• Digital: Deals with data in the form of numbers; performs arithmetic and logical operations.
• Hybrid: Combines characteristics of both analog and digital.

By size:

• Palmtop / PDA, small, touch-screen based, Laptop / Notebook, portable, battery-powered, Personal Computer (PC), general use, single person, Desktop, not portable, high performance, Micro-computer, came with the microprocessor, Mini-computer, more powerful than micro, less than mainframe, Mainframe, very high speed, used in banking, airlines, Supercomputer, fastest; used for weather forecasting, molecular modelling, cryptanalysis

IPO Cycle (Input-Process-Output)

• Input: Data is fed through input devices.
• Process: CPU processes the data using instructions.
• Output: Result is presented in human-readable form., Result can be used immediately or saved for future use.

Computer Ports and Cables

• PS/2 Ports: 6-pin, low-speed serial connections for keyboard and mouse.
• VGA (Video Graphics Array): Connects monitor; supports up to 256 colours at 320x400, 16 colours at 640x480.
• Parallel Port: Transfers multiple bits at a time; used for printers.
• Ethernet Port: Built-in port for wired network connection.
• S-Video Port: Transmits video by separating colour (chrominance) and brightness (luminance) signals.
• USB Port: Supports up to 127 peripheral devices; supports Plug-and-Play and hot plugging; 12 Mbps.
• FireWire (IEEE 1394): High-speed data transfer for digital devices; faster than USB. Invented by Apple.
• Mini Audio Jack: Audio connectors for plugs (male) and jacks (female).

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Important Definitions

Term	Definition
Data	Collection of unprocessed facts, figures, and symbols
Information	Processed, organised, meaningful, and useful form of data
Hardware	Physical components of a computer that can be seen and touched
Software	Set of instructions that tells the computer to perform tasks
RAM	Volatile primary memory that can be read and written; data lost on power off
ROM	Non-volatile primary memory; permanently stores boot-up instructions; read-only
CPU	Central Processing Unit; interprets and carries out basic instructions
ALU	Arithmetic and Logic Unit; executes arithmetic and logical operations
GIGO	Garbage In Garbage Out; valid input produces correct output
IPO	Input-Process-Output cycle
Binary	Number system using only digits 0 and 1
Bit	Single binary digit (0 or 1)
Byte	A sequence of 8 bits
OS	Operating System; manages programs, files, and hardware
Decryption	Process of decoding data that has been encrypted into secret format

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Key Points

1. A computer takes raw data as input, processes it using a program, and gives the result as output.
2. RAM is volatile; ROM is non-volatile. Both are primary memory.
3. Secondary memory is cheaper and stores data permanently.
4. The five generations of computers track the evolution from vacuum tubes to parallel processing and nanotechnology.
5. Computers are classified by function (analog, digital, hybrid) and by size (palmtop to supercomputer).
6. USB supports Plug-and-Play and can connect up to 127 devices.
7. FireWire is faster than USB for data transfer.
8. The IPO cycle is the fundamental working model of any computer.

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Practice Questions

Multiple Choice (selected):

1. Collection of unprocessed facts, figures, and symbols is known as?, (c) Data
2. Hardware is any part that has a physical structure?, (a) True
3. Which disk stores more than 25 GB?, (c) Blu-Ray
4. RAM and ROM are examples of?, (a) Primary Memory
5. Binary number system uses only?, (b) Binary number system
6. Two primary types of software?, (c) Application Software and System Software
7. Which generation used transistors?, (b) II Generation
8. By functioning, computers are divided into?, (b) Analog, Digital and Hybrid
9. High-speed cabling technology?, (b) FireWire

Short Answer:

1. Explain RAM, Nibble, Digital Computers, Ethernet Port.
2. Name two utility softwares.
3. Why is auxiliary memory needed?
4. Differentiate: Hardware vs Software, RAM vs ROM, Application vs System Software, Digital vs Analog.
5. Explain the functions of an operating system.
6. Explain all generations of computers.
7. Draw and explain the IPO cycle.
8. Name 4 application areas of computers.
9. How are computers classified by processing capabilities?
10. Differentiate between Ethernet Port and USB.