Definition of Information Technology :“IT (Information Technology)encompasses all of the technologies thatwe use in order to create, collect, process,protect and store information. It refers to hardware, software (computer programs), and computer networks”.
Computer : The word Computer is derived from a Latin word “computare” which means to “to calculate”, “to count”, “to sum up” or “to think together”.
An electronic device which accepts input from the user, processes it according to the instructions given to it and gives the required result in the form of output, is a computer.
Computer System :
A computer can process data, images, audio, video and graphics. A computer performs five major computer operations or functions irrespective of their size and make. These are -
1) It accepts data or instructions by way of input.
2) It stores data.
3) It can process data as required by the user.
4) It gives results in the form of output.
It controls all operations inside a computer.
Architecture of Computer : Computer Architecture is a specification detailing of how a set of software and hardware technology standards interact to form a computer system. In short, com- puter architecture refers to how a comput- er system is designed and how it works
Every computer system has the following three basic components :
1. Input Unit
2. Central Processing Unit
3. Output Unit
1. Input Unit : This unit helps users to enter data and commands into a computer system. Data can be in the form of numbers, words, actions, commands, etc. The main function of input devices is to direct commands and data into computer. Computer then uses its CPU to process data and produce output. e.g.Mouse,Keyboard.
2.Central Processing Unit (CPU) : After receiving data and commands from users, a computer system has to process it according to the instructions provided.
The CPU further uses these three elements :
a) Arithmetic and Logic Unit : This part of the CPU performs arithmetic operations. It does basic mathematical calculations like addition, subtraction, division, multiplication, etc.
b) Control Unit : This unit is the back bone of computers. It is responsible for coordinating tasks between all components of a computer system.
c) Memory Unit : Once a user enters data using input devices, the computer system stores this data in its memory unit.
Types of Memory– There are two types of memory
1) Primary Memory 2) Secondary Memory
1) Primary Memory : Primary memory is internal memory of the computer. It is also known as main memory.
Types of Primary Memory– Primary memory is generally of two types.
1. RAM 2. ROM
1. RAM (Random Access Memory): It stands for Random Access Memory. RAM is known as read /write memory. It is generally referred to as main memory of the computer system. It is a temporary memory. The information stored in this memory is lost as the power supply to the computer is switched off. That’s why RAM is also called as “Volatile Memory”.
2. ROM (Read Only Memory) : It stands for Read Only Memory. ROM is a Permanent Type memory. The content is not lost when power supply is switched off. Content of ROM is decided by the computer manufacturer and permanently stored at the time of manufacturing. ROM cannot be overwritten by the computer. It is also called “Non-Volatile Memory”.
2) Secondary Memory : It is an external memory of the computer. It is used to store the huge amount of different programs and information.
The secondary storage devices are :
1. Magnetic (Hard) Disk
2. Magnetic Tapes
3. Pen Drive
4. Flash memory
5. Optical Disk (CD,DVD)
6. SSD etc.
3. Output Unit : The third and final component of a computer system is the output unit. After processing of data, it is converted into a format which human can understand. After conversion, the output unit displays this data to users.
Units of Memory : Computer storage and memory is often measured in Megabytes (MB) and Gigabytes (GB). Let us understand the evolution of memory.
Bit : It is a binary digit that holds only one of two values : 0 or 1.
Nibble : A group of 4 bits is called a nibble (For example:1011, 1001, 1111).
Byte : A group of 8 bits is called a byte. A byte is the smallest unit, which can represent a data item or a character. (For example : 11101100, 10000001)
Different Units of Memory
Data Measurement Size
Bit Single Binary Digit(1 or 0)
1 Byte 8 Bits
1 KiloByte (KB) 1,024 Bytes
1 MegaByte (MB) 1,024 KiloBytes
1 GigaByte (GB) 1,024 MegaBytes
1 TeraByte (TB) 1,024 GigaBytes
1 PetaByte (PB) 1,024 TeraBytes
1 ExaByte (EB) 1,024 PetaBytes
Concept of Hardware and Software :
Categories of a software :
Types of a software :
Application Software : Application software is a program or group of programs designed for end users. Applications software (also called end-user programs) include programs like database programs, word processors, web browsers, presentation software, spreadsheets etc.
System Software : System Software is a set of instructions required for a computer to work. Operrating system is the example of system software.
A computer would not be able to function correctly without an operating system.
Operating Systems for Personal Computers :
DOS : DOS (Disk Operating System) was the dominant operating system for microcomputers in the 1980's and the early 1990's. For working with DOS the user needs to know how to input the commands using the Command Prompt Window.
Windows : Windows is a series of operating systems that are designed by Microsoft. The first two versions of the Windows operating system, introducedin 1985 and 1987 respectively, were primitive. Windows is the most commonly used operating system.
Mac OS : Apple Corporation’s registered operating system is called Mac OS.
Chrome OS : Chrome OS is an open-source operating system created by Google to create a better computing experience for people who spend most of their time on the web.
UNIX : UNIX was trademarked in 1969 by a group of AT&T employees at Bell Labs as a multitasking, and multi-user computer operating system.
Linux : Linux is an open-source, portable, multi-user (multiple users can access system resources like memory/RAM/ application programs at the same time), multiprogramming, operating system. It is very similar to other operating systems, such as Windows and a source code is available to the public.Operating Systems for Mobile Phones :
There are many different operating systems for mobile phones and devices. These are Android, Asha, Blackberry, iOS, Windows Phone etc.
Android : Android is a free and open source operating system provided by Google. It is most popular OS amongst all other OS.
Asha : Asha is used by Nokia phones. This is closed source OS.
Blackberry : This is a closed source operating system for smartphone and tablet devices.
iOS : iOS is Apple's closed source operating system for Apple's iPhone, iPod Touch, iPad and second-generation Apple TVs.
Windows Phone : Windows Phone is developed by Microsoft as a closed source operating system for mobile phones
Graphical User Interface (GUI)
The graphical user interface is when the user interacts with the computer using images, icons, and dialog boxes.
URL-Uniform Resource Locator
URL stands for Uniform Resource Locator. A URL is nothing more than the address of a given unique resource on the Web.
e.g. https://www.mahahsscboard.in/
Computer Network
Introduction : It is a group of interconnected computers or devices to have communication within themselves. A computer network consists of a collection of computers, printers and other equipment that is connected together so that they can communicate with each other.
Types of networks : There are three types of network based on the geographical area they cover : LAN, MAN and WAN.
1) Local Area Network (LAN) :
l LAN covers smaller geographical area (Size is limited to a few kilometers) and are privately owned.
l Usage area is limited to areas such as an office building, home, hospital, schools, etc.
l It covers a short distance, and so the error and noise are minimized.
l LAN is easy to setup.
l Data transmits at a very fast rate as the number of computers linked are limited.
l It is a less expensive hardware and maintenance cost is also low.
2) Metropolitan Area Network (MAN) :
l MAN is larger area than that of a LAN and smaller area as compared to WAN.
l It connects two or more separate computers that reside in the same or different cities.
l It covers a large geographical area and may serve as an ISP (Internet Service Provider).
l It is hard to design and maintain a Metropolitan Area Network.
3) Wide Area Network (WAN) :
l Wide Area Network is a computer network that extends over a large geographical area.
l It might be confined within the bounds of a state or country.
l A WAN could be a connection of LAN connecting to other LAN’s via telephone lines and radio waves.
l The technology is high speed and relatively expensive.
l A Communication medium used for WAN is Telephone Network or Satellite Link.
l Due to long distance transmission, the noise and error tends to be more in WAN.
Internet :
Internet means connecting computer to any other computer anywhere in the world. Internet is the highway of information.
The Internet has one very simple job: to move computerized information (known as data) from one place to another. The Internet is generally defined as a global network connecting millions of computers.
History of Internet :
The first workable prototype of the internet came in the late 1960's with the creation of ARPANET, or the Advanced Research Projects Agency Network. Originally funded by the U.S. Department of Defense, ARPANET used packet switching to allow multiple computers to communicate on a single network. The technology continued to grow in the 1970's after scientists Robert Kahn and Vinton Cerf developed Transmission Control Protocol and Internet Protocol, or TCP/IP, a communications model that set standards for how data could be transmitted between multiple networks. ARPANET adopted TCP/IP on January 1, 1983, and from there researchers began to assemble the “network of networks” that became the modern Internet. The online world then took on a more recognizable form in 1990, when computer scientist Tim Berners-Lee invented the World Wide Web (WWW).
Protocols :
A protocol is a set of rules that governs the communications between computers on a network. In order to have two computers to talk to each other, they must be speaking the same language.
Examples of Protocols are-
l TCP/IP : Transmission Control Protocol & Internet Protocol - It breaks down the message into packets and sends them out into the network.
l DNS : Domain Name System-It translates network address (such as IP addresses) into terms understood by humans (such as Domain Names) and vice-versa.
l DHCP : Dynamic Host Configuration Protocol - It can automatically assign internet addresses to computers and users.
l FTP : File Transfer Protocol - A protocol that is used to transfer and manipulate files on the internet.
l HTTP : HyperText Transfer Protocol- An internet-based protocol for sending and receiving web pages.
l IMAP : Internet Message Access Protocol - A protocol for receiving e-mail messages from server on the Internet. It maintains a copy of all the emails on server. We can sort, filter emails.
l IRC : Internet Relay Chat - A protocol used for Internet chat and other communications. It facilitates communication in the form of text.
l POP3 : Post Office Protocol Version 3
- A protocol used for receiving e-mail from remote mail servers. It does not maintain copy on the server.
l SMTP : Simple Mail Transfer Protocol - A protocol for sending e-mail messages to the Server on the Internet.
