COMPUTER SYSTEM (CLASS -XI) (PART - 4)

 COMPUTER SYSTEM  

(PART -IV)

CLASS - XI

Storage Unit

Computer need to store and retrieve data for processing. Since primary memory has a limited storage capacity and is not permanent, secondary storage devices are used to store large amount of data permanently. There are various types of secondary devices available these days.

Hard Disks: A hard disk is a set of stacked disks. Each disk has data recorded electromagnetically in concentric circles, or tracks, on the disk. The hard disks of today have storage capacity measured in giga bytes upto tera bytes.

CD/DVD: The compact disk or CDs are optical media. The CDs are relatively cheap and have a storage capacity upto 700 mb. DVD can hold upto 17 GB of data

Flash Memory: A flash device is a small, ultra-portable storage device. It has no moving parts unlike magnetic storage device.

Blue Ray Disk: It is an optical disc storage media format. Its main uses are high-definition video and data storage.

Types of Software

The software can be classified into two categories:

     System Software

     Application Software

System Software: The software that controls internal computer operations is called system software.

The system software can further be classified into two categories.

     Operating System

     Language Processor

Operating System: The primary goal of an operating system is thus to make the computer system convenient to use and secondary goal is use to computer hardware in an efficient manner. An operating system is an important component of a computer system which controls all other components of the computer system.

Language Processor: A language processor is a special type of computer software that can translate the source code into an object code or machine code.

There are 3 types of language processors:

Assembler: This language processor converts the program written in assembly language into machine language.

Interpreter: An interpreter is a type of system software that translates and executes instructions written in computer program line-by-line, unit-by-unit etc.

Compiler: A Compiler is another type of system software that translates and executes instructions written in a computer program in one go.

Application Software: An Application Software is a set of programs necessary to carry out operations for a specified application.

Application software can further be subdivided into four categories:

        Package               Utilities                 Customized Software                    Developer Tools

Package: Some most common categories of general application software are:

•  Word processing software

• Spreadsheet

• Database Management System

• Desktop Publishing Software

• Graphics, multimedia, and presentation applications.

Utilities: Utilities are those application programs that assists the computer by performing housekeeping functions like backing up disk or scanning/cleaning viruses or arranging information etc.

Business Software: This type of software is specifically created software according to business requirements. This type of software is developed to meet the general requirements of a business. A company wants to computerize its ‘Accounts’ department and get a software that can serve its needs. Such a software is business software.

Examples : Inventory Management /system, Payroll system, Financial Accounting, Hotel Management software etc.

Software Libraries: A software library is a predefined and available to use, suite of data and programming code in the form of prewritten code/functions/scripts/classes etc. that can be used in the development of new software programs and applications.

For Example, Python comes equipped with many software libraries. Some of these are:

NumPy (Numerical Python):It provides an abundance of useful features and functions for operations on numeric arrays and matrices in Python.

SciPy (Scientific Python): SciPy contains modules for liner algebra, optimization, integration, and statistics.

Pandas Library: Pandas is a python package designed to do work with “labeled” and “relational” data. It is designed for quick and easy data manipulation, aggregation, and visualization.

DEVELOPMENT OF COMPUTER/CALCULATOR TO SMART DEVICE

Abacus is known to be the first mechanical calculating device. Which was used to be performed addition and subtraction easily and speedily? This device was a first develop Ed by the Egyptians in the 10th centaury B.C, but it was given it final shape in the 12th centaury A.D. by the Chinese educationists.

NAPIER’S BONES John Napier’s of Scotland invented a calculating device, in the year 1617 called the Napier Bones. In the device, Napier’s used the bone rods of the counting purpose where some no. is printed on these rods. These rods that one can do addition, subtraction, multiplication and division easily.

Pascal's calculator In the year 1642, Blaise Pascal a French scientist invented an adding machine called Pascal’s calculator, which represents the position of digit with the help of gears in it.

Leibnz Calculator In the year 1671, a German mathematics, Gottfried Leibniz modified the Pascal calculator and he developed a machine which could perform various calculation based on multiplication and division as well.

Analytical EngineIn the year 1833, a scientist form England knows to be Charles Babbage invented such a machine. Which could keep our data safely? This device was the first mechanical computer. Charles Babbage is also known as the father of the computer.

1943-1944: Two University of Pennsylvania professors, John Mauchly and J. Presper Eckert, build the Electronic Numerical Integrator and Calculator (ENIAC). Considered the grandfather of digital computers

1976: Steve Jobs and Steve Wozniak start Apple Computers on April Fool's Day and roll out the  Apple i, the first computer with a single-circuit board, according to Stanford University.

2007: The iPhone brings many computer functions to the smartphone.

GENERATION OF COMPUTER

Generation	Year	Characteristics
1st	1944 – 59	Use Valves (Vacuum tubes)
2nd	1959 – 64	Use transistors
3rd	1964 –75	Large Scale Integrated Circuits
4th	1975 -	Very Large-Scale Integrated Circuits
5th	Under development	Artificial Intelligence based computers

Trouble shooting with parts of computer

• First check the cable. Unplug it from the computer and the outlet. Replug in both sides and try booting it again.

• Check the wall outlet. Plug something else into the outlet and see if it works. If have a surge protector try a different outlet.

• Turn the system off and wait 30 seconds and then try again.

• Reach behind the machine and see if feel air blowing out of the power supply. If do, then you know the machine is getting some power.

• Look at the keyboard for the indicator lights being lit up as the machine boots.

• Sometimes the monitor has something to do with the system acting up. Unplug the power cord from the monitor and the wall and re-plug it. Unplug the cable from the computer to the monitor and re-plug it into the monitor. Try rebooting.

COMPUTER SYSTEM (CLASS - XI) (PART - 3)

COMPUTER SYSTEM

Units of computer Memory

S. No.	Unit	Short Name	Full Name
1	1 Bit	Bit	Binary Digit
2	8 Bits	1 Byte	Byte
3	210 i.e. 1024 Bytes	1 KB	Kilo Byte
4	210 i.e. 1024 KB	1 MB	Mega Byte
5	210 i.e. 1024 MB	1 GB	Giga Byte
6	210 i.e. 1024 GB	1 TB	Terra Byte
7	210 i.e. 1024 TB	1 PB	Peta Byte
8	210 i.e. 1024 PB	1 EB	Exa Byte
9	210 i.e. 1024 EB	1 ZB	Zetta Byte

Memory Access Time: The amount of time taken to produce data required from memory, from the start of access until the availability of data, is called Memory Access Time.

Parts of Main Memory (Primary Memory):

The main memory divided into two parts:

RAM (Random Access Memory)
ROM (Read Only Memory)

Random Access Memory: It is the memory cells that can be accessed for information transfer from any desired random location. That is, the process of locating a word in memory is the same and requires an equal amount of memory, thus the name “random access”.

The main drawback of RAM memory is that it is a volatile memory. That is, when the power goes off, the contents of RAM get erased.

Types of RAM

The RAM chips in a computer can be of two types:

Dynamic RAM (DRAM)

Static RAM (SRAM)

Dynamic RAM (DRAM): Dynamic RAM consists of a transistor and capacitor that’s capable of storing an electric charge. Depending on the switching action of the transistor, the capacitor either contains no charge (0 bit) or does hold a charge (1 bit). The dynamic RAM provides volatile storage i.e. contents are lost in the event of power failure.

Static RAM (SRAM): SRAM is also volatile but as they are supplied with power, they need no special regenerator circuits to retain the stored data. The static RAM consists eventually of internal flip-flop that store the binary information. The stored information remains valid as long as power is applied to the unit.

Note: A flip-flop is a binary cell capable of storing one bit of information.

Read Only Memory (ROM):  ROM refers to read only memory where only read operation can take place. The ROM is a non-volatile memory. Both RAM and ROM are parts of primary memory.

There are various types of ROM which are given below:

1.      Programmable Read Only Memory (PROM)

2.      Erasable Programmable Read Only Memory (EPROM)

3.      Electrically Erasable Programmable Read Only Memory (EEPROM)

COMPUTER SYSTEM (CLASS - XI) (PART - 2)

COMPUTER SYSTEM

OUTPUT UNIT

The output unit is formed by the output devices attached to the computer. The output coming from the CPU is in the form of electronic binary signals which needs conversion on some form which can be easily understand by human. The function of conversion is performed by output units.

Another words we say, A device that can receive data from computer or another device and create output with data is called output device.

Some output devices are:

Monitor: A monitor is an output device that is responsible for receiving data from computer and displaying that information as characters, graphical and audio visual form for users to see.

Speakers: It receive the sound in the form of electric current from the sound card and then convert it to sound format audible to users.

Printers: It is the device that deliver information by means of printed characters on paper.

Projector: Gets data from a computer and displays or projects the same information onto a screen or a wall. Projector cannot directly accept data from a user and send that data to another device.

INPUT/OUTPUT DEVICES

An I/O device is capable of receiving data from users or other devices and also sending data to another devices or computers. That means a device which can be used as both input device and output device are called I/O devices. Examples:

USB (Universal Serial Bus): Also known as pen drive or flash stick works as both input device to computer and as an output device. USB drives receive or save data from a computer as an input and it can also send data to a computer or another device.

Modems (Modulator-demodulator): It is used to transmit and receive data from one computer to another computer or other devices using telephone lines.

Facsimile: Facsimile or FAX machine has a scanner which is an input device and a small printer to provide output.

Handset: Handset consists of speaker as an output device and microphone function as an input device.

Touch Screen: Touch screen is both input and output device. By touching screen input is provided and being a screen, it is used as an output device.

 CPU (Central Processing Unit)

It is also called brain of the computer as it guides, directs, controls and governs the performance of a computer. The CPU has some sub-complements that help in carrying out the processing task.

These are:

1.Arithmetic Logic Unit (ALU)

2.Control Unit (CU)

3.Registers

Arithmetic Logic Unit (ALU): The ALU performs all the arithmetic operations like addition, subtraction, multiplication & subtraction and some logical operations like (<, >, =, <=, >=, !=).

Control Unit (CU): Control Unit acts as a supervisor by controlling and guiding the operation taking place.

Registers: Registers or Processor registers are small units of data holding places. ALUs have a small amount of special storage units called registers that can be accessed faster than main memory.

Memory: A collection of cells, each with a unique physical address. The memory of computer is often called main memory or primary memory.

The memory of a computer can be thought of as ‘cells’. Each of these cells is further broken down into smaller part known as bits. A bit means a binary digit i.e., either 0 or 1. A number of bits together are used to store data instructions by their combination.

COMPUTER SYSTEM (CLASS - XI) (PART - 1)

COMPUTER SYSTEM

Chapter -1

INTRODUCTION

A computer is an electronic device, under the control of instructions stored in its memory that can accept data (input), process the data according to specified rules (Program), produce information (output), and store the information for future use.

Because of different units work as a single unit in computer for central objective, that’s why it is a system, i.e. computer system.

Data: Data are raw numbers or other finding which, by themselves, are of limited value.

Information: It is data that has been converted into a meaningful and useful context.

Any digital computers perform these functions in gross term.

1.      Take data as input

2.      Stores data/instructions

3.      Process those stored data

4.      Generate the output

5.      Control all above steps

Input Unit

A device through which data and programs from the outside world enter the computer system.

Output Unit

A device through which result stored in the computer memory are made available outside the computer system.

Input Devices Input devices can send data or information to a computer or another device. Keyboard: It is an input device which sends data in to the computer. The data send depends on the key pressed by the user.

Mouse: A mouse is a small handheld input device which controls a cursor in a graphical user interface. It can move and select text, files, folders etc. on our computer according to the user input.

Scanner: Scanner optically reads and document, file or image and then changes it into digital signal and sends to the computer.

OMR: optical mark recognition/ reader, is used to read marks on a document and send them to computer.

OCR: OCR stands for optical character Recognition, is an input device which reads printed text and sends that to computer.

MICR: Magnetic Ink Character Reader is an input device which generally finds application is banks to process cheques.

Microphone: it receives audio generated by some input source and sends the same to a computer.

Webcam: it sends the captured images to a computer.

Graphics Tablets: This input device is used to draw using hand.

Trackballs: an upside down mouse, encased within a socket. Is a cursor control device.

Barcode reader: It is used to read the barcode of various items and feed the same to computer.

Gamepad: Also known as joy pad is the input controller for video games.

Joystick: these input devices are used to control video games.

INTERNET BASICS PART -1

INTERNET BASICS

The internet is a network of computers linking many different types of computers all over the world. Internet is a global computer network providing a variety of information and communication facilities, consisting of interconnected networks using standardized communication protocols.

INTERNET AND ITS COMPONENT

Access, Chat, Ecommerce, E-mail, FTP, Hosting, Mailing list, Search Engines, Telnet, Usenet, World Wide Web- are the common components of the internet. Different components have different roles.

There are the components including- modem, broadband filter, router etc, that many users are unaware of.

WORLD WIDE WEB

The World Wide Web commonly known as the web. It is a way of accessing information over the Internet. It contains millions of documents called Web Pages. Each page contains text, graphics, audio, video, and links to other web page via hyperlinks. The web uses HTTP (Hyper Text Transfer Protocol) for the transfer of these documents over the Internet.

Sir Tim Berners Lee, along with Robert Cailliau, invented the World Wide Web while working at CERN (Europian Council for Nuclear Reserch) in 1990. In this time, the World Wide Web is the most significant database of human knowledge.

HOW DOES WWW WORK?

A person who use the Internet uses a software known as Web Browser to request for a document or a web page located somewhere on the web. The browser requests the Internet host/server which contains that document. The browser thus acts as a customer or a client. After receiving the request, the Internet host passes the information to the clients. A network protocol controls the flow in this model. The protocol used in this exchange is called Hypertext Transfer Protocol(HTTP).

DIFFERENCE BETWEEN WWW AND INTERNET

Internet	World Wide Web
·        It is a global network connecting millions of computers.	·        It is a system of internet servers that support specially formatted documents.
·        The internet is decentralized.	·        Documents are formatted in a markup language that supports links to other documents.
·        Each internet computer is independent.	·        You can jump from one document to another simply by clicking on hot spots (hyperlinks).
·        There are a variety of ways to access the internet. ·	·        Applications called web browsers that make it easy to access the World Wide Web.
·        There are more than 3.5 billion internet users in the world.	·        There are more than 1,275,000,000 websites.
·        The Internet is administered by the Internet Protocol (IP)	·        WWW is managed by Hypertext Transfer Protocol (HTTP)

BASIC INTERNET TERMINOLOGY

SERVER:- A Server is a program that runs on a machine and is meant to provide services to machines (clients) connected to it. It accepts the requests which come to it from a client, processes the requests, generates the response, and sends the required information to the client. The communication between a client and server uses HTTP protocol.

CLIENT:- A client is a computer system which uses a network to access a remote service from the server. It carries out the user’s/client’s request to the server and displays the results sent by the server. It can access the applications or information from the main server. A client is also known as a node.

WEB CLIENT:- A web client is an application (e.g. Internet Explorer, Google Chrome, Mozilla) running on a local device like your desktop, notebook, cell phone that requests and uses services provided by a web server. It is also known as thin client because it relies heavily on the web server for fetching the information from it.

A web client and web server are two components of a connection. A client is any machine sending the requests for information, and the server is responding to the information requested. Some examples of a web client are web browser, an e-mail, a chatting programm and file sharing programs.

WEB BROWSER:- It is a software application through which one searches and accesses information on the World Wide Web. For example, Google Chrome, Mozilla Firefox, Internet Explorer, Opera etc.

WEB PAGE:- A web page is a document commonly written in HTML (Hypertext Markup Language) that is hosted on the Internet.

WEBSITE:- A website is a collection of publicly accessible interlinked web pages, containing related information, located under a single domain name.

DOMAIN NAME:- It is a unique name given to each website.

URL:- The Uniform Resource Locater donates the global address of the document and other resources on the World Wide Web. The communication between a web user and an Internet resource is possible by identifying each resource on the Internet in a standard manner.

WEB PORTAL:- It is a  gateway to wide range of Internet services, such as an e-mail, search engines, forums, e-commerce etc.

BLOG OR WEB BLOG:- A blog is a frequently updated online personal journal or diary. It is an easy-to-create website, which consists of a signed and dated log of individual posting.

BLOGGER:- A author of a blog is known as a blogger who regularly writes and updates the blog.

BLOGGING:- The act of writing a blog is called blogging.

E-MAIL (ELECTRONIC MAIL):- it is an electronic messaging system that allows one to send and receive letters and attachments (Images, videos, and other files) in real time.

NEWSGROUP:- It is an online platform where people can exchange information on any topic.

E-MAIL ADDRESSES:- The general format of an email address is local-part@domain, and a specific example is san@example.com. An address consists of two parts. The part before the @ symbol (local part) identifies the name of a mailbox. This is often the username of the recipient, e.g., san.

3 Parts of an Email Address

·        Username. The first part of an email address is the username. ...

·        @ Symbol. An “at,” or “@,” symbol is the second part of an email address. ...

·        Domain. The last part of an email address is the domain, which can be broken down into two portions: the mail server and the top-level domain.

WEB SERVER

A Server is a program that runs on a machine and is meant to provide services to machines (clients) connected to it. It accepts the requests which come to it from a client, processes the requests, generates the response, and sends the required information to the client. The communication between a client and server uses HTTP protocol.

Web servers are computers that deliver (serves up) Web pages. Every Web server has an IP address and possibly a domain name. For example, if you enter the URL http://www.google.com in your browser, this sends a request to the Web server whose domain name is google.com.

Types of web servers –

·        Apache Web Server.

·        IIS Web Server.

·        Nginx Web Server.

·        LiteSpeed Web Server.

·        Apache Tomcat.

·        Node. js.

·        Lighttpd.

DIFFERENCE BETWEEN SERVER AND WEB SERVER

SERVER	WEB SERVER
A server is a type of computer or device on a network that provides services to machines (clients) connected to it.	A web server is a program or a computer, primarily responsible for providing web contents. It stores, processes, and delivers web contentment in the form of text, pictures, videos, and animations to its clients.
Server manage hardware and software resources in a network.	A web server is designed to serve only HTTP requests from a web browser and respond with an HTTP response, such as sending back an HTML page.
A server be a shared server or a dedicated server.	A web server is a dedicated server.
A server provides access to server-side logic (Server Applications) using the language supported by the server, such as C#, PHP, Java.	It can only display static HTML content on the web browser.
The various types of server are application server, file server, print server, communication server, and domain server.	Some commonly web servers are Apache Server, Microsoft IIS Server, IBM Lotus, and Sun Java System.