2. Agri- Informatics
Theory: Introduction to Computers, Operating Systems, definition and types, Applications of MS-Office
for document creation & Editing, Data presentation, interpretation and graph creation, statistical
analysis, mathematical expressions, Database, concepts and types, uses of DBMS in Agriculture, World
Wide Web (WWW): Concepts and components. Introduction to computer programming languages,
concepts and standard input/output operations. e-Agriculture, concepts and applications, Use of ICT in
Agriculture. Computer Models for understanding plant processes. IT application for computation of
water and nutrient requirement of crops, Computer-controlled devices (automated systems) for Agri-
input management, Smartphone Apps in Agriculture for farm advises, market price, postharvest
management etc; Geospatial technology for generating valuable agri-information. Decision support
systems, concepts, components and applications in Agriculture, Agriculture Expert System, Soil
Information Systems etc for supporting Farm decisions. Preparation of contingent crop-planning using
IT tools.
Practical: Study of Computer Components, accessories, practice of important DOS Commands.
Introduction of different operating systems such as windows, Unix/ Linux, Creating, Files & Folders, File
Management. Use of MS-WORD and MS Power-point for creating, editing and presenting a scientific
Document. MS-EXCEL - Creating a spreadsheet, use of statistical tools, writing expressions, creating
graphs, analysis of scientific data. MS-ACCESS: Creating Database, preparing queries and reports,
demonstration of Agri-information system. Introduction to World Wide Web (WWW). Introduction of
programming languages. Hands on Crop Simulation Models (CSM) such as DSSAT/Crop-Info/CropSyst/
Wofost; Computation of water and nutrient requirements of crop using CSM and IT tools. Introduction
of Geospatial Technology for generating valuable information for Agriculture. Hands on Decision
Support System. Preparation of contingent crop planning.
4. Introduction to Computers
A computer can be defined as an electronic device capable of processing the
data and producing the information.
The computer system essentially comprises three important parts –
• input device,
• central processing unit (CPU) and
• output device.
The CPU itself is made of three components namely,
• arithmetic logic unit (ALU),
• memory unit, and
• control unit.
On broad basis, a computer performs the following tasks:
Input: Sending the data and command to the computer is known as input.
Processing: Work done by the computer with the help of processing hardware and
software to produce results is known as processing.
Output: The result displayed by the computer is known as output.
Storage: A place to save result inside or outside the computer is known as storage.
5. Anatomy of Computers
The following are the parts of a desktop
computer.
Power Supply
When you plug your power cable into your computer, you are actually plugging into a
socket in the power supply unit that has been fitted inside your case. This component is
responsible for converting the 240 volt AC mains power to low voltage DC power needed
by computer components. The power supply generates +3.3V, +5V, +12V, -5V. These
voltages must be constant, right up to the maximum current your system will draw under
load.
Monitor- Commonly known as a "screen," the monitor gives you a visual display of what
your computer is up to. Monitor displays are divided into pixels. The higher the pixel count,
the higher the "resolution." Resolutions are measured in Rows x Columns. Common
resolution settings are 640 x 480, 800 x 600, 1024 x 768, 1280 x 1024, etc.
6. Mother board
The mainboard I which is sometimes called a motherboard. This is usually the largest
circuit-board in the computer, and every other component in the computer connects to it.
Central Processing Unit
The Central Processing Unit (CPU)is usually called either a CPU or just a Processor. The CPU is
the brain of the system. It executes all the program code from the operating system and the
applications the user runs and processing of data. It sends CPU commands to direct the
actions of all the other components in the computer.
An Intel CPU
7. Main Memory or Random Access Memory (RAM)
RAM, which stands for Random Access Memory, is
the short term memory that the computer uses to
keep track of what it's doing. If the computer loses
power, anything stored in RAM is lost.
8. INPUT AND OUTPUT DEVICES
Input Devices
Input device is a hardware device that sends information to the computer.
Mouse
Mouse Mouse is a pointer device.The mouse allows an individual to control a pointer in a
graphical user interface (GUI). Utilizing a mouse a user has the ability to perform various
functions such as opening a program or file and does not require the user to memorize
commands.
A type of camera that stores the pictures or video it takes in electronic
format instead of to film.
9. Web Cam
A camera connected to a computer that allows anyone connected to the Internet to view
still pictures or motion video of a user.
Joystick
A computer joystick allows an individual to easily navigate an object in a game such as
navigating a plane in a flight simulator.
Keyboard
One of the main input devices used on a computer, a computer keyboard looks very similar
to the keyboards of electric typewriters, with some additional keys.
10. Microphone
Sometimes abbreviated as mic, a microphone is a hardware peripheral
that allows computer users to input audio into their computers.
Scanner
Input device that allows a user to take an image and/or text and
convert it into a digital file, allowing the computer to read and/or
display the scanned object
11. Output Device
Any peripheral that receives and/or displays output from a computer. Below are some
examples of different types of output devices commonly found on a computer.
Monitor
A monitor is a video display screen. Monitor is also called as Visual Display Unit
(VDU) or Video Display Terminal (VDT).
CRT (Cathode Ray Tube) Monitors are built very similarly to older (tube) television
sets. They are heavy, bulky, , take up a lot of desk space, and emit radiation.
CRT (Cathode Ray Tube) Monitors
LCD (Liquid Crystal Display) Monitors are thin and flat. They are light, compact, take up
very little desk space emit no known radiation.
LCD (Liquid Crystal Display) Monitor
12. Printer
A printer is an output device responsible for taking computer data and generating a hard copy
of that data.
Projector
Speakers
13.
14.
15. First Generation of Computer
• The period 1940 to 1956, roughly considered as the First Generation of Computer.
• The first generation computers were developed by using vacuum tube or thermionic
valve machine.
• The input of this system was based on punched cards and paper tape; however, the
output was displayed on printouts.
• The first generation of computers was heavy in weight as about 30 tones and was very
large …
• They consumed high energy.
• As they used thousands of vacuum tubes through which they heated very soon.
vacuum tubes. First Generation of computer
16. Second Generation of Computer
• The period of second generation was from 1959-1965. In this generation, transistors were
used that were cheaper, consumed less power, more compact in size, more reliable and
faster than the first generation machines made of vacuum tubes.
• In this generation, magnetic cores were used as the primary memory and magnetic tape
and magnetic disks as secondary storage devices.
• In this generation, assembly language and high-level programming languages like
FORTRAN, COBOL were used. The computers used batch processing and
multiprogramming operating system.
Characteristics of the second generation of computer are:
Smaller in size: The Second generation of computers are much more smaller in size
than the first generation computers.
Change in circuits: The main change is the use of transistors in place of vacuum tubes(
Vacuum tubes are used in first generation of computers).
Power/ Energy Requirement: The second generation of computers requires less
amount of energy (i.e. electricity) compared to the first generation of computers and
produces less heat than the first-generation computer.
Language used: Assembly language is used instead of Machine Language(used in first-
generation computers) for programming in computers.
Speed: Calculation of data could be done in microseconds.
Cost: The cost of Second-generation computers is reduced in comparison to first-
generation computers.
17. Advantages of second-generation computers:
They are smaller in size as compare to the first generation.
It is more reliable
Uses less power and generates less heat.
The speed of the second generation is faster as compared to the first generation.
Second generation computers have improved accuracy and offer better portability.
Disadvantages of second-generation computers:
As we know, that they generate less heat but still require a cooling system.
They require frequent maintenance.
The commercial production of second generation computers is difficult.
They are used only for some specific purpose.
They use punch cards for input.
18. Third Generation of Computer
• Third generation computers are advance from first and second generation computers.
The third generation computer was started in 1965 and ended around 1971.
• Third generation computers start using integrated circuits instead of transistors.
• The integrated circuit (IC) is a semiconductor material, that contains thousands of
transistors miniaturized in it. With the help of IC, the computer becomes more reliable,
fast, required less maintenance, small in size, generates less heat, and is less expensive.
• It was developed by Robert Noyce of Fairchild Semiconductor and Jack Kilby (American
electrical engineer) of Texas Instruments in 1958. So due to ICs, the third generation
computers are much faster, efficient, reliable, less maintenance, and small in size as
compared to first and second generation computers.
• Third generation computer uses less electricity but still, they are little expensive and also
use the air conditioner for cooling.
19. Characteristics of Third Generation Computers:
• As compared to previous generations, the third generation computers were more reliable,
fast, efficient, less expensive, and smaller in size.
• In third generation computers, high-level programming languages were used such as
BASIC, PASCAL, ALGOL-68, COBOL, FORTRAN – II, PASCAL PL/1.
• The punch cards were replaced with mouse and keyboards.
• The integrated circuit technology replaces the use of individual transistors.
• The computers have high storage capacity.
Advantages of Third Generation Computers:
• Computer required less space due to the use of integrated circuits (IC). A single integrated
circuit (IC) contains transistors, resistors, condensers, condensers, etc. on a piece of the
silicon semiconductor substrate.
• It produces less head and required less energy during operations. Due to this third
generation computers have less hardware failure as compare to previous generations.
• In third generation computers, the punch cards were removed and the input was taken
with the help of a mouse and keyboards.
• They have high storage capacity and give more accurate results, which helps to store and
compute and calculate more precise operations.
• The computers were portable and offer better speed.
Disadvantages of Third Generation Computers:
• These computers still required air conditioning.
• To manufacture IC, highly sophisticated technology was required.
• Maintaining IC chips were difficult.
20. • After third-generation computers, which mostly utilized microprocessors, fourth-
generation computers were released in 1972.
• VLSI technology, or Very Large Scale Integrated (VLSI) circuits, was employed in these
computers. As a result, they were dubbed microprocessors.
• A microprocessor is made up of thousands of integrated circuits that are assembled on
a single chip known as a silicon chip.
Fourth Generation of Computer
Architecture
The fourth generation of computers contains five separate units and they are
input, arithmetic and logic, memory, output, and control units. The physical
location of the computer’s functional unit is depicted in the diagram below. Users
enter data (digital information) into the unit using input devices such as a mouse,
keyboard, microphone, and so on. The data is either processed or not based on
the type of input.
21. Features of Fourth Generation Computers
• Following are the features of fourth-generation computers:
• Very Large Scale Integrated (VLSI) circuits are used in a microprocessor-based system.
• In this generation, microcomputers became the most affordable.
• Handheld computers have grown in popularity and cost.
• In this age, networking between systems was invented and became commonplace.
• The quantity of memory and other storage devices available has expanded dramatically.
• The outputs are now more consistent and precise.
• The processing power, or speed, has skyrocketed.
• With the expansion of storage systems’ capacity, huge programs began to be used.
• Great advancements in hardware aided in the improvement of the screen, paper, and other output.
• Multiple high-level languages, such as BASIC, PASCAL, COBOL, FORTRAN, and C, were developed in the fourth
generation.
Advantages Fourth Generation of Computer
• Following are some advantages of fourth-generation computers:
• They were designed to be used for a wide range of purposes (general-purpose computers).
• Smaller and more dependable than previous generations of computers.
• There was very little heat generated.
• In many circumstances, the fourth-generation computer does not require a cooling system.
• Portable and less expensive than previous versions.
• Computers from the fourth generation were significantly quicker than those from previous generations.
• The Graphics User Interface (GUI) technology was used to provide users with better comfort. During this time, PCs
became more inexpensive and widespread.
• Repair time and maintenance costs are reduced.
• They were also created with the intention of being used in commercial production.
• In this form of computer, any type of high-level language can be employed.
Disadvantages of the Fourth Generation of Computer
• Following are some disadvantages of fourth-generation computers:
• The fabrication of the ICs necessitated the use of cutting-edge technologies (Integrated Circuits).
• Only ICs can be made with a high-quality and reliable system or technology.
• Microprocessors must be manufactured using cutting-edge technology, which necessitates the use of a cooler (fan).
22. Five Generation of Computer
• Fifth-generation computers were introduced after the fourth-generation computers were
invented.
• Fifth-generation computers, also known as modern computers, are still in the development
stage and are based on artificial intelligence.
• In 1982, Japan was invented the FGCS (Fifth Generation Computer System).
• Computers of this generation are based on microelectronic technology with high computing
power and parallel processing.
Features of Fifth-generation Computers
• The ULSI (ultra large scale integration) technology is used in this generation of
computers.
• Natural language processing is now in its fifth phase of development.
• In this generation’s computers, artificial intelligence has progressed.
• Parallel processing has advanced on these computers.
• The fifth-generation computer includes more user-friendly interfaces and multimedia
functions.
• These PCs can be purchased for a lower price.
• Computers that are more portable and powerful.
• Computers are dependable and less expensive.
• It’s easier to manufacture in a commercial setting.
• Desktop computers are straightforward to operate.
• Mainframe computers are extremely efficient.
23. Advantages of Fifth Generation of Computer
• These computers are far quicker than previous generations.
• These computers are simpler to repair.
• These computers are substantially smaller in size than other generation computers.
• They are lightweight and easy to move.
• True artificial intelligence is being developed.
• Parallel Processing has progressed.
• Superconductor technology has progressed.
Disadvantages of Fifth Generation of Computer
• They’re usually sophisticated but could be difficult to use.
• They can give businesses additional power to monitor your activities and potentially
infect your machine.
24. Memory of Computer
A memory is just like a human brain. It is used to store data and instructions. Computer
memory is the storage space in the computer, where data is to be processed and
instructions required for processing are stored. The memory is divided into large number
of small parts called cells. Each location or cell has a unique address, which varies from
zero to memory size minus one. For example, if the computer has 64k words, then this
memory unit has 64 * 1024 = 65536 memory locations. The address of these locations
varies from 0 to 65535.
Memory is primarily of three types −
• Cache Memory
• Primary Memory/Main Memory
• Secondary Memory
• Cache Memory
Cache memory is a very high speed semiconductor memory which can speed up the CPU.
It acts as a buffer between the CPU and the main memory. It is used to hold those parts of
data and program which are most frequently used by the CPU. The parts of data and
programs are transferred from the disk to cache memory by the operating system, from
where the CPU can access them.
25. Advantages
• Cache memory is faster than main memory.
• It consumes less access time as compared to main memory.
• It stores the program that can be executed within a short period of time.
• It stores data for temporary use.
Disadvantages
• The disadvantages of cache memory are as follows −
• Cache memory has limited capacity.
• It is very expensive.
Primary Memory (Main Memory)
• Primary memory holds only those data and instructions on which the computer is currently
working.
• It has a limited capacity and data is lost when power is switched off.
• It is generally made up of semiconductor device.
• These memories are not as fast as registers.
• The data and instruction required to be processed resides in the main memory.
• It is divided into two subcategories RAM and ROM.
26. Characteristics of Main Memory
• These are semiconductor memories.
• It is known as the main memory.
• Usually volatile memory.
• Data is lost in case power is switched off.
• It is the working memory of the computer.
• Faster than secondary memories.
• A computer cannot run without the primary memory.
RAM and ROM Memory
• RAM stands for random access memory and is the temporary storage component (short-
term memory) of a computer.
• RAM holds all the data you’re currently using, from the website you’re looking at to the
movement of your mouse from one side of the screen to the other.
• Whenever you do anything on your computer, you execute a lot of processes. Type a
sentence, save a document, jump in a video game — behind all of that work is your
RAM. And it’s much easier (faster) to do those tasks if the data is stored in your
computer’s RAM, where it’s easily accessible, rather than the hard drive (SSD OR HDD).
• Now that you know what RAM is and what it stands for, you’ll have a much better idea
of how RAM works to help your computer streamline your work.
Inserting RAM sticks into their slots on a computer’s motherboard.
27. Types of memory
Computers use several different types of memory. They are:
Main Memory / Primary Memory units
Two most important are
RAM (Random Access Memory)
ROM (Read-only Memory)
They work in different ways and perform distinct functions
CPU Registers
Cache Memory
Secondary Memory/Auxiliary Memory
Also termed as ‘auxiliary’ or ‘backup’ storage, it is typically used as a supplement to main storage. It is
much cheaper than the main storage and stores large amount of data and instructions permanently.
Hardware devices like magnetic tapes, Floppy Disk, Hard Disk, Optical disks, Compact Disk (CD), Digital
Versatile Disk (DVD) and Blu-ray Disc (BD) fall under this category.
Computer’s memory can be classified into two types – RAM and ROM.
RAM or Random Access Memory is the central storage unit in a computer system. It is the place in a
computer where the operating system, application programs and the data in current use are kept
temporarily so that they can be accessed by the computer’s processor. The more RAM a computer has, the
more data a computer can manipulate.
Random access memory, also called the Read/Write memory, is the temporary memory of a computer. It is
said to be ‘volatile’ since its contents are accessible only as long as the computer is on. The contents of
RAM are cleared once the computer is turned off.
ROM or Read Only Memory is a special type of memory which can only be read and contents of which are
not lost even when the computer is switched off. It typically contains manufacturer’s instructions. Among
other things, ROM also stores an initial program called the ‘bootstrap loader’ whose function is to start the
computer software operating, once the power is turned on.
28. Different types of RAM
There are two main types of RAM: SRAM and DRAM.
• SRAM (static random access memory) data is stored in transistors and uses (low) power
constantly to keep data fresh. That’s why it’s called static, because it doesn’t need to be
refreshed. SRAM is used in cache memories, like the small files your processor (CPU) accesses
all the time.
• DRAM (dynamic random access memory) data is stored in capacitors and slowly discharges
power. That’s why it’s called dynamic, because the gradual energy decline means that it needs
to be refreshed periodically to work properly. When the power is cut, the electrical charges
dissipate and the RAM is emptied of data.
• The advantage of SRAM is that it uses less power and data can be accessed more quickly. But
the cost of manufacturing is higher. DRAM’s advantage is that it’s cheaper and offers better
memory capacity, but it’s also a bit slower when accessing data and consumes more power.
• Another type of RAM is SDRAM, which is a subset of DRAM. SDRAM (synchronous dynamic
RAM) connects RAM to the computer’s system clock. Syncing the memory to the system clock
brings your memory up to speed.
• The pulse of the system clock can be pictured as a sine wave. At each peak of the wave, the
SDRAM transmits data. DDR (double data rate) is a new technology that lets data be sent
whenever the “lower” part of the pulse (the sine wave’s valley) goes through. With DDR, data
is sent twice during each clock cycle, so you get speeds that are twice as fast.
• The second generation, DDR2, allows for even more data to be sent during these two data-
delivery periods. Each new generation of DDR increases this bandwidth. Currently, most
computers work with DDR4. With each new generation of DDR, less power is consumed, due
to lower voltage requirements.
29. Read Only Memory (ROM)
There are 4 types of ROM out of them, 3 are the most common. These are as follows:
• MROM (masked read only memory)
• PROM (programmable read only memory)
• EPROM(erasable and programmable read only memory)
• EEPROM(electrically erasable and programmable read only memory)
MROM (Masked Read Only Memory)
These were the very first ROMs. Furthermore, these are hard-wired devices that contain a pre-
programmed set of data and instructions. Moreover, they are inexpensive in nature.
PROM (Programmable Read Only Memory)
It is the programmable ROM that the user can program but only once. Furthermore, the user writes the
data and instructions using a PROM program. Moreover, after writing once the user cannot change or
erase the data and instructions.
EPROM (Erasable and Programmable Read Only Memory)
We can reprogram this memory by erasing the data. Furthermore to erase the data it has to be exposed
to ultraviolet light. During the programming, a charge is trapped in the insulated gate region. Besides, on
exposing it to the ultraviolet light for around 40 minutes this charge destroys. Hence, in this way, the data
gets erased. After erasing the data we can now reprogram the ROM.
EEPROM (Electrically Erasable and Programmable Read Only Memory)
We can program and erase this memory electrically. Furthermore, we do not require any ultraviolet light
to erase the data. Moreover, erasing and reprogramming is possible many times. Besides, we can erase
any particular location of the memory selectively. At the same time, we can delete only one byte from the
memory at a time rather than erasing the whole chip. Therefore, the process of reprogramming is flexible
and slow.
30. Software
Software is a general term for the various kinds of programs used to operate computers and
related devices. Software is classified as follows:
System software
System software refers to the operating system and all utility programs that manage
computer resources at a low level. Operating system controls and manages the computing
resources. Examples of operating system: Windows, Unix, MSDOS, Linux, Mac.
Systems software includes compilers, loaders, linkers, and debuggers.
31. Applications software comprises programs designed for an end user, such as word processors,
database systems, and spreadsheet programs. Application software makes computer popular
and easy to use. Common application software:
1. Microsoft Word, WordPerfect
2. PowerPoint
3. Netscape, Internet Explorer
4. Photoshop, Photo-Paint
5. Quick Time
6. Dreamweaver
Classification of Computers
• Computers are available in different shapes, sizes and weights, due to these different
shapes and sizes they perform different sorts of jobs from one another. They can also be
classified in different ways. All the computers are designed by the qualified computer
architectures that design these machines as their requirements.
• A computer that is used in a home differs in size and shape from the computer being
used in a hospital. Computers act as a server in large buildings, while the computer also
differs in size and shape performing its job as a weather forecaster.
• A student carrying a laptop with him to his college is different in shape and size from all
the computers mentioned above. Computers are classified as follows:
32. Computer virus is a small software program that is designed to
spread from one computer to another and to interfere with
computer operation. A true virus is capable of self replication on a
machine. Virus may spread between files or disks.
There are estimated 30,000 computer viruses in existence.
Over 300 new ones are created each month.
First virus was created to show loopholes in software.
Today almost 87% of all viruses are spread through the internet.
Symptoms of Virus Attack
1. Computer runs slower than usual
2. Computer no longer boots up
3. Screen sometimes flicker
4. Speaker beeps periodically
5. System crashes for no reason
6. Files/directories sometimes disappear
7. Denial of Service (DoS)
Computer Viruses
33. Types Computer Viruses
1. Trojan Horse
1. Requires Windows to work
2. Once infected, runs in the background
2. Worm
1. Spread over network connection
2. Worms replicate
3. Macro
1. Specific to certain applications
2. Comprise a high percentage of the viruses
4. E-mail viruses
1. An e-mail virus travels as an attachment to e-mail messages, and usually replicates itself by
automatically mailing itself to dozens of people in the victim's e-mail address book.
2. Some e-mail viruses don't even require a double-click -- they launch when you view the infected
message in the preview pane of your e-mail software.
Worms
A worm is a small piece of software that uses computer networks and security holes to replicate itself. A copy of the
worm scans the network for another machine that has a specific security hole. It copies itself to the new machine using
the security hole, and then starts replicating from there, as well.
Worms use computer time and network bandwidth when they replicate. A worm called Code Red made huge
headlines in 2001. Experts predicted that this worm could clog the Internet so effectively that things would completely
grind to a halt.
A worm usually exploits some sort of security hole in a piece of software or the operating system. For example, the
Slammer worm (which caused mayhem in January 2003) exploited a hole in Microsoft's SQL server.
Worms normally move around and infect other machines through computer networks. Using a network, a worm can
expand from a single copy incredibly quickly. The Code Red worm replicated itself more than 250,000 times in
approximately nine hours on July 19, 2001.
Protect computer against viruses:
34. Vaccines
Vaccines or Antivirus software is a computer program that detects, prevents, and takes action to disarm or
remove malicious software programs, such as viruses and worms. New viruses, worms, and other threats
are created by cyber terrorists and discovered every day. So updating antivirus software is periodically
mandatory. List of some top Anti Virus Programs which are veryusefl to users:
Norton AntiVirus – Norton AntiVirus is the most popular and secure virus scanner for checking boot sector
records at startup. The live update feature automatically installs new updates for regular protection against
viruses.
AVG Free Edition – AVG Resident Shield provides real-time protection executions of files and programs. It
features a smart e-mail scanner, virus updates and virus vault for secure handling of the files which are
infected by viruses. The base version for windows is Free for private and non-commercial use.
McAfee VirusScan for Windows: This antivirus package detects all virus types, including Word and Excel
macros; boot-sector infections; and file, multipartite, stealth, polymorphic, and encrypted viruses.
Kaspersky Anti-Virus Personal Pro – It is a commonly used virus protection solution offering full
protection against macro-viruses and unknown viruses.
ESET NOD32 Antivirus – ESET NOD32 Anti-virus is available as an anti-virus for small businesses,
individuals and for large networks.
avast! Home Edition – A free antivirus solution for scanning disk, CDs, and E-mail.
35. Operating System
Operating system is a set of software that controls and manages hardware and basic system
operations for a computer. The operating system loads programs into the computer's
memory, runs these programs, and manages peripherals like disks and printers.
Disk Operating System (DOS)
Windows
LINUX
Mac
UNIX
36. Disk Operating System (DOS)
In the 1980s or early 1990s, the operating system that shipped with most PCs was a version
of the Disk Operating System (DOS)created by Microsoft: MS-DOS.
MS-DOS is a disk-based, single-user, single-task and character based user interface (CUI)
operating system.
Goto MSDOS from Windows Operating System:
Click Start Button à Choose Program à Choose Accessories à Click Command Prompt as
shown below:
37. Or Click Start Button à Choose Run à Type cmd in the Open tab as shown below:
Command Prompt will get displayed as shown:
The DOS commands can be entered in the
command prompt and executed
38. If information on the date / time and other information on the files are not needed, then this
command can be used to list just the files and directories going horizontally, taking as little as
space needed.
dir /w
List the files in alphabetical order by the names
of the files.
List the files in alphabetical order by the names of the files.
dir /on
39. Word and Character Representation
Digital Computers use Binary number system to represent all types of
information inside the computers. Binary number system is suitable for this
purpose due to following reasons:
• Electronic components in digital computers operate in binary mode. A switch is
either on (1) or off (0); a transistor is either conducting (1) or non-conducting(0).
• Computers have to handle only two digits (bits) rather than 10. So binary
system simplifies design, reduce the cost and improve the reliability of the
computer.
• Everything that can be done with decimal system can also be done using a
binary system.
40. Word and Character Representation
Character Codes-Representation of alphanumeric characters in bits 0 and
1 is done by character codes. There are three widely used character codes:
• Binary Coded Decimal(BCD)
• American standard Code for Information Interchange (ASCII)
• Extended Binary Coded Decimal Interchange Code(EBCDIC)
Binary Coded Decimal (BCD)
BCD uses 6 bits and can represent 26 =64 characters.
The first three bits are used as zone bits and the last three bits indicate the
digit.
41. Word and Character Representation
American Standard Code for Information Interchange (ASCII ) Code
ASCII-7: uses 7 bits and can represent 27=128 characters. The first three bits
are used as zone bits and the last four bits indicate the digit. Hexadecimal
numbers are used as shortcut notation for memory dump.
44. Word and Character Representation
Integer representation:
The binary numbers used in digital computers must be represented by using
binary storage devices such as Flip-Flops (FF). Each device represent one bit.
The most direct number system representation for binary valued storage
devices is an integer representation system. Simply writing the value or
states of the flip-flops gives the number in integer form.
For example, a 6-bit FF register could store binary numbers ranging from
000000 to 111111 (0 to 63 in decimal). Since digital computers handle +ve as
well as –ve numbers, some means is required for representing the sign of the
number (+ or -).
This is usually done by placing another bit called sign bit to the left of the
magnitude bits. 0 in sign bit position represent a +ve number while a 1 in
sign bit position represent a –ve number.
55. Machine Language (low level language)
Low-Level language is the only language which can be understood by the computer.
Low-level language is also known as Machine Language. The machine language
contains only two symbols 1 & 0. All the instructions of machine language are written in
the form of binary numbers 1's & 0's. A computer can directly understand the machine
language.
Assembly Language (middle level language)
Middle-level language is a computer language in which the instructions are created using symbols
such as letters, digits and special characters. Assembly language is an example of middle-level
language. In assembly language, we use predefined words called mnemonics. Binary code
instructions in low-level language are replaced with mnemonics and operands in middle-level
language. But the computer cannot understand mnemonics, so we use a translator
called Assembler to translate mnemonics into machine language.
Assembler is a translator which takes assembly code as input and produces machine code as output.
That means, the computer cannot understand middle-level language, so it needs to be translated
into a low-level language to make it understandable by the computer. Assembler is used to translate
middle-level language into low-level language.
e.g., g++ -S main.cpp -o main.s
56. High Level Language
High-level language is a computer language which can be understood by the users. The high-level
language is very similar to human languages and has a set of grammar rules that are used to
make instructions more easily. Every high-level language has a set of predefined words known as
Keywords and a set of rules known as Syntax to create instructions. The high-level language is
easier to understand for the users but the computer can not understand it. High-level language
needs to be converted into the low-level language to make it understandable by the computer.
We use Compiler or interpreter to convert high-level language to low-level language.
Languages like FORTRAN,C, C++, JAVA, Python, etc., are examples of high-level languages. All
these programming languages use human-understandable language like English to write program
instructions. These instructions are converted to low-level language by the compiler or
interperter so that it can be understood by the computer.
63. An Operating System (OS) is an interface between a computer user and
computer hardware. An operating system is a software which performs all the
basic tasks like file management, memory management, process management,
handling input and output, and controlling peripheral devices such as disk drives
and printers.
Some popular Operating Systems include Linux Operating System, Windows
Operating System, VMS, OS/400, AIX, z/OS, etc.
Following are some of important functions of an operating System
Operating System (OS)
Memory Management
Processor Management
Device Management
File Management
Security
Control over system performance
Job accounting
Error detecting aids
Coordination between other software and
users
65. Batch operating: The users of a batch operating system do not interact with
the computer directly. Each user prepares his job on an off-line device like
punch cards and submits it to the computer operator.
The problems with Batch Systems are as follows −
• Lack of interaction between the user and the job.
• CPU is often idle, because the speed of the mechanical I/O devices is slower
than the CPU.
• Difficult to provide the desired priority.
Types of Operating System (OS)
Time-sharing operating systems:
Time-sharing is a technique enables many people, located at various
terminals, to use a particular computer system at the same time. Time-
sharing or multitasking is a logical extension of multiprogramming.
Processor's time which is shared among multiple users simultaneously is
termed as time-sharing.
66. Advantages of Timesharing operating systems are as follows −
• Provides the advantage of quick response.
• Avoids duplication of software.
• Reduces CPU idle time.
Types of Operating System (OS)
Distributed operating System:
Distributed systems use multiple central processors to serve multiple real-
time applications and multiple users. Data processing jobs are distributed
among the processors accordingly.
The processors communicate with one another through various
communication lines (such as high-speed buses or telephone lines). These
are referred as loosely coupled systems or distributed systems. Processors
in a distributed system may vary in size and function. These processors are
referred as sites, nodes, computers, and so on.
67. The advantages of distributed systems are as follows −
• With resource sharing facility, a user at one site may be able to use the
resources available at another.
• Speedup the exchange of data with one another via electronic mail.
• If one site fails in a distributed system, the remaining sites can potentially
continue operating.
• Better service to the customers.
• Reduction of the load on the host computer.
• Reduction of delays in data processing.
Types of Operating System (OS)
Network operating System
A Network Operating System runs on a server and provides the server the capability to
manage data, users, groups, security, applications, and other networking functions. The
primary purpose of the network operating system is to allow shared file and printer
access among multiple computers in a network, typically a local area network (LAN), a
private network or to other networks.
Examples of network operating systems include Microsoft Windows Server 2003,
Microsoft Windows Server 2008, UNIX, Linux, Mac OS X, Novell NetWare, and BSD
68. Types of Operating System (OS)
Network operating System
A real-time system is defined as a data processing system in which the time interval
required to process and respond to inputs is so small that it controls the environment.
The time taken by the system to respond to an input and display of required updated
information is termed as the response time. So in this method, the response time is very
less as compared to online processing.
Real-time systems are used when there are rigid time requirements on the operation of
a processor or the flow of data and real-time systems can be used as a control device in
a dedicated application. A real-time operating system must have well-defined, fixed
time constraints, otherwise the system will fail. For example, Scientific experiments,
medical imaging systems, industrial control systems, weapon systems, robots, air traffic
control systems, etc.
69. Introduction to Linux Operating System
Linux is a community of open-source Unix like operating systems that are based on
the Linux Kernel. It was initially released by Linus Torvalds on September 17, 1991.
It is a free and open-source operating system and the source code can be modified
and distributed to anyone commercially or non-commercially under the GNU
General Public License.
Initially, Linux was created for personal computers and gradually it was used in
other machines like servers, mainframe computers, supercomputers, etc. Nowadays,
Linux is also used in embedded systems like routers, automation controls,
televisions, digital video recorders, video game consoles, smartwatches, etc.
The biggest success of Linux is Android(operating system) it is based on the Linux
kernel that is running on smartphones and tablets. Due to android Linux has the
largest installed base of all general-purpose operating systems. Linux is generally
packaged in a Linux distribution.
70. Introduction to Linux Operating System
• MX Linux
• Manjaro
• Linux Mint
• elementary
• Ubuntu
• Debian
• Solus
• Fedora
• openSUSE
• Deepin
Types:
71. Kernel: Kernel is the core of the Linux based operating system. It virtualizes the
common hardware resources of the computer to provide each process with its
virtual resources. This makes the process seem as if it is the sole process running on
the machine. The kernel is also responsible for preventing and mitigating conflicts
between different processes. Different types of the kernel are:
Monolithic Kernel
Hybrid kernels
Exo kernels
Micro kernels
System Library: Is the special types of functions that are used to implement the
functionality of the operating system.
Shell: It is an interface to the kernel which hides the complexity of the kernel’s
functions from the users. It takes commands from the user and executes the
kernel’s functions.
Hardware Layer: This layer consists all peripheral devices like RAM/ HDD/ CPU
etc.
System Utility: It provides the functionalities of an operating system to the user.
72. Advantages of Linux
• The main advantage of Linux, is it is an open-source operating system. This
means the source code is easily available for everyone and you are allowed to
contribute, modify and distribute the code to anyone without any permissions.
• In terms of security, Linux is more secure than any other operating system. It
does not mean that Linux is 100 percent secure it has some malware for it but is
less vulnerable than any other operating system. So, it does not require any anti-
virus software.
• The software updates in Linux are easy and frequent.
• Various Linux distributions are available so that you can use them according to
your requirements or according to your taste.
• Linux is freely available to use on the internet.
• It has large community support.
• It provides high stability. It rarely slows down or freezes and there is no need to
reboot it after a short time.
• It maintain the privacy of the user.
• The performance of the Linux system is much higher than other operating
systems. It allows a large number of people to work at the same time and it
handles them efficiently.
• It is network friendly.
73. • The flexibility of Linux is high. There is no need to install a complete Linux
suit; you are allowed to install only required components.
• Linux is compatible with a large number of file formats.
• It is fast and easy to install from the web. It can also install on any hardware
even on your old computer system.
• It performs all tasks properly even if it has limited space on the hard disk.
Disadvantages of Linux
• It is not very user-friendly. So, it may be confusing for beginners.
• It has small peripheral hardware drivers as compared to windows.
74. Microsoft Windows is a multitasking operating system developed by Microsoft
Corporation which uses Graphical User Interface to interact with the users.
Microsoft was originally named “Traf-O-Data” in 1972, was renamed as “Micro-
soft” in November 1975, then “Microsoft” on November 26, 1976.
Microsoft entered the marketplace in August 1981 by releasing version 1.0 of the
operating system Microsoft DOS (MS-DOS), a 16-bit command-line operating
system. Bill Gates and Paul Allen founded Microsoft and windows operating system
has been its primary product.
Introduction to Windows Operating System
83. Internet & World Wide Web
The internet is a globally connected network system that transmit data via
various types of media. The internet is a network of global exchanges –
including private, public, business, academic and government networks –
connected by guided, wireless and fiber-optic technologies.
The terms internet and World Wide Web are often used interchangeably, but
they are not exactly the same thing; the internet refers to the global
communication system, including hardware and infrastructure, while the web
is one of the services communicated over the internet.
Internet Protocol (IP): The internet’s primary component and communications
backbone. Because the internet is comprised of hardware and software layers,
the IP communication standard is used to address schemes and identify unique
connected devices. Prominent IP versions used for communications include
Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6).
84. World Wide Web (WWW)
The World Wide Web is abbreviated as WWW and is
commonly known as the web. The WWW was initiated
by CERN (European library for Nuclear Research) in
1989.
History:
It is a project created, by Timothy Berner Lee in 1989,
for researchers to work together effectively at CERN. is
an organization, named the World Wide Web
Consortium (W3C), which was developed for further
development of the web. This organization is directed
by Tim Berner’s Lee, aka the father of the web.
85. World Wide Web (WWW)
The World Wide Web or Web is basically a collection of
information that is linked together from points all over the world.
It is also abbreviated as WWW.
• World wide web provides flexibility, portability, and user-
friendly features.
• It mainly consists of a worldwide collection of electronic
documents (i.e, Web Pages).
• It is basically a way of exchanging information between
computers on the Internet.
• The WWW is mainly the network of pages consists of images,
text, and sounds on the Internet which can be simply viewed on
the browser by using the browser software.
• It was invented by Tim Berners-Lee.
86. The WWW is mainly a distributed client/server service where a client using the
browser can access the service using a server. The Service that is provided is
distributed over many different locations commonly known as sites/websites.
• Each website holds one or more documents that are generally referred to as
web pages.
• Where each web page contains a link to other pages on the same site or at
other sites.
• These pages can be retrieved and viewed by using browsers.
Architecture of WWW
88. In the above case, the client sends some information that belongs to site A. It
generally sends a request through its browser (It is a program that is used to fetch
the documents on the web).
and also the request generally contains other information like the address of the
site, web page(URL).
The server at site A finds the document then sends it to the client. after that when
the user or say the client finds the reference to another document that includes the
web page at site B.
The reference generally contains the URL of site B. And the client is interested to
take a look at this document too. Then after the client sends the request to the new
site and then the new page is retrieved.
Now we will cover the components of WWW in detail.
Architecture of WWW
89. 1.Client/Browser
The Client/Web browser is basically a program that is used to communicate with
the webserver on the Internet.
Each browser mainly comprises of three components and these are:
1. Controller
2. Interpreter
3. Client Protocols
The Controller mainly receives the input from the input device, after that it uses the
client programs in order to access the documents.
After accessing the document, the controller makes use of an interpreter in order to
display the document on the screen.
An interpreter can be Java, HTML, javascript mainly depending upon the type of the
document.
The Client protocol can be FTP, HTTP, TELNET.
Architecture of WWW
90. 2.Server
The Computer that is mainly available for the network resources and in order to
provide services to the other computer upon request is generally known as the
server.
• The Web pages are mainly stored on the server.
• Whenever the request of the client arrives then the corresponding document is
sent to the client.
• The connection between the client and the server is TCP.
• It can become more efficient through multithreading or multiprocessing.
Because in this case, the server can answer more than one request at a time.
Architecture of WWW
91. 3.URL
URL is an abbreviation of the Uniform resource locator.
• It is basically a standard used for specifying any kind of information on the Internet.
• In order to access any page the client generally needs an address.
• To facilitate the access of the documents throughout the world HTTP generally makes
use of Locators.
URL mainly defines the four things:
• Protocol It is a client/server program that is mainly used to retrieve the document. A
commonly used protocol is HTTP.
• Host Computer It is the computer on which the information is located. It is not
mandatory because it is the name given to any computer that hosts the web page.
• Port The URL can optionally contain the port number of the server. If the port number is
included then it is generally inserted in between the host and path and is generally
separated from the host by the colon.
• Path It indicates the pathname of the file where the information is located.
Architecture of WWW
92. 4.HTML
HTML is an abbreviation of Hypertext Markup Language.
It is generally used for creating web pages.
It is mainly used to define the contents, structure, and organization of the web page.
5.XML
XML is an abbreviation of Extensible Markup Language. It mainly helps in order to define
the common syntax in the semantic web.
Architecture of WWW
Features of WWW
Given below are some of the features provided by the World Wide Web:
• Provides a system for Hypertext information
• Open standards and Open source
• Distributed.
• Mainly makes the use of Web Browser in order to provide a single interface for
many services.
• Dynamic
• Interactive
• Cross-Platform
93. Components of the Web: There are 3 components of the web:
1. Uniform Resource Locator (URL): serves as a system for resources on the web.
2. HyperText Transfer Protocol (HTTP): specifies communication of browser and
server.
3. Hyper Text Markup Language (HTML): defines the structure, organisation and
content of a webpage.
94. The C programming language is a general-purpose, high-level language that
was originally developed by Dennis M. Ritchie to develop the UNIX operating
system at Bell Labs. C was invented to write an operating system called UNIX.
Facts about C:
The language was formalized in 1988 by the American National Standard
Institute. (ANSI).
The UNIX OS was totally written in C by 1973.
Today, C is the most widely used and popular System Programming
Language.
Most of the state-of-the-art softwares have been implemented using C.
Today's most popular Linux OS and RBDMS MySQL have been written in C
C Language Overview
95. Before we start doing programming using C programming language, we need the
following two softwares available on our computer, (a) Text Editor and (b) The C
Compiler.
Text Editor:
• This will be used to type your program. Examples of few editors include Windows
Notepad, OS Edit command, Brief, Epsilon, EMACS, and vim or vi.
• Name and version of text editor can vary on different operating systems. For
example, Notepad will be used on Windows, and vim or vi can be used on windows
as well as Linux or UNIX.
• The files you create with your editor are called source files and contain program
source code. The source files for C programs are typically named with the extension
“.c”.
Note: Before starting your programming, make sure you have one text editor in place and you have enough
experience to write a computer program, save it in a file, compile it and finally execute it.
C Environment Setup
96. The C Compiler:
• The source code written in source file is the human readable source for your
program. It needs to be "compiled", to turn into machine language so that your CPU
can actually execute the program as per instructions given.
• This C programming language compiler will be used to compile your source code
into final executable program. Most frequently used and free available compiler is
GNU C/C++ compiler, otherwise you can have compilers either from HP or Solaris if
you have respective Operating Systems.
C Environment Setup
97. C Hello World Example:
A C program basically consists of the following parts:
• Preprocessor Commands
• Functions
• Variables
• Statements & Expressions
• Comments
Let us look at a simple code that would print the words "Hello World":
C Program Structure
98. C Hello World Example:
1. The first line of the program #include <stdio.h> is a preprocessor command, which
tells a C compiler to include stdio.h file before going to actual compilation.
2. The next line int main() is the main function where program execution begins.
3. The next line /*...*/ will be ignored by the compiler and it has been put to add
additional comments in the program. So such lines are called comments in the
program.
4. The next line printf(...) is another function available in C which causes the message
"Hello, World!" to be displayed on the screen.
5. The next line return 0; terminates main()function and returns the value 0.
C Program Structure
99. Tokens in C:
A C program consists of various tokens and a token is either a keyword, an identifier, a
constant, a string literal, or a symbol. For example, the following C statement consists
of tokens.
Semicolons:
In a C program, the semicolon is a statement terminator. That is, each individual
statement must be ended with a semicolon. It indicates the end of one logical entity.
C - Basic Syntax
100. Comments:
Comments are like helping text in your C program and they are ignored by the
compiler. They start with /* and terminate with the characters */ as shown below-
Identifiers:
• A C identifier is a name used to identify a variable, function, or any other user-
defined item. An identifier starts with a letter A to Z, a to z, or an underscore '_'
followed by zero or more letters, underscores, and digits (0 to 9).
• C does not allow punctuation characters such as @, $, and % within identifiers. C is
a case-sensitive programming language. Thus, Manpower and manpower are two
different identifiers in C. Here are some examples of acceptable identifiers −
C - Basic Syntax
101. Identifiers:
Keywords:
The following list shows the reserved words in C. These reserved words may not be
used as constants or variables or any other identifier names.
C - Basic Syntax
102. Whitespace in C:
A line containing only whitespace, possibly with a comment, is known as a blank line,
and a C compiler totally ignores it.
C - Basic Syntax
