First generation computers used machine language and could only solve one problem at a time. Input was via punched cards and paper tape, and output was printed. Examples included the UNIVAC and ENIAC. Second generation computers introduced symbolic languages like assembly languages and early versions of COBOL and FORTRAN. Storage moved from drums to magnetic cores. Third generation computers saw the introduction of operating systems to provide a software platform for applications. Fourth generation computers featured graphical user interfaces with icons, windows, menus, pointers and desktop workspaces to make programs easier to use. Fifth generation computers involve artificial intelligence techniques like expert systems, neural networks and robotics.

1. First Generation of Computer:-
First generation computers relied on machine language, the
lowest-level programming language understood by computers, to perform operations, and
they could only solve one problem at a time. It would take operators days or even weeks to
set-up a new problem. Input was based on punched cards and paper tape, and output was
displayed on printouts.
The UNIVAC and ENIAC computers are examples of first-generation computing devices.
The UNIVAC was the first commercial computer delivered to a business client, the U.S.
Census Bureau in 1951.
Second Generation of Computer:-
Second-generation computers moved from cryptic binary machine
language to symbolic, or assembly, languages, which allowed programmers to specify
instructions in words. High-level programming languages were also being developed at this
time, such as early versions of COBOL and FORTRAN. These were also the first computers
that stored their instructions in their memory, which moved from a magnetic drum to
magnetic core technology.
The first computers of this generation were developed for the atomic energy industry.
Third Generation of computer:-
In this generation the operating system used.
This is a fantastic computer of the time. Operating systems
provide a software platform on top of which other
programs, called application programs, can run. The
application programs must be written to run on top of a
particular operating system. Your choice of operating
system, therefore, determines to a great extent the
applications you can run. For PCs, the most popular
operating systems are DOS, OS/2, and Windows, but others
are available, such as Linux.
Operating system is very useful for the computers. It is a biggest discovery of the time.

2. ClassificationofOperating systems:-
Multi-user: Allows two or more users to run programs at the same time. Some operating
systems permit hundreds or even thousands of concurrent users.
Multiprocessing: Supports running a program on more than one CPU.
Multitasking: Allows more than one program to run concurrently.
Multithreading: Allows different parts of a single program to run concurrently.
Real time: Responds to input instantly. General-purpose operating systems, such as DOS and
UNIX, are not real-time.
User Interaction With the OS:-
As a user, you normally interact with the operating system through a set of
commands. For example, the DOS operating system contains commands such as COPY and
RENAME for copying files and changing the names of files, respectively. The commands are
accepted and executed by a part of the operating system called the command processor or
command line interpreter. Graphical user interfaces allow you to enter commands by pointing
and clicking at objects that appear on the screen.
Fourth Generation of Computer:-
GUI:-
It is observation of Graphical User Interface. GUI is a program interface that takes
advantage of the computer's graphics capabilities to make the program easier to use. Well-
designed graphical user interfaces can free the user from learning complex command
languages. On the other hand, many users find that they work more effectively with a
command-driven interface, especially if they already know the command language.
He first graphical user interface was designed by Xerox Corporation's Palo Alto Research
Center in the 1970s, but it was not until the 1980s and the emergence of the Apple Macintosh
that graphical user interfaces became popular. One reason for their slow acceptance was the
fact that they require considerable CPU power and a high-quality monitor, which were
prohibitively expensive.
Pointer: A symbol that appears on the display screen and that you move to select objects and
commands. Usually, the pointer appears as a small angled arrow. Text -processing
applications, however, use an I-beam pointer that is shaped like a capital I.
Pointing device: A device, such as a mouse or trackball that enables you to select objects on
the display screen.
Icons: Small pictures that represent commands, files, or windows. By moving the pointer to
the icon and pressing a mouse button, you can execute a command or convert the icon into a

3. window. You can also move the icons around the display screen as if they were real objects
on your desk.
Desktop: The area on the display screen where icons are grouped is often referred to as the
desktop because the icons are intended to represent real objects on a real desktop.
Windows: You can divide the screen into different areas. In each window, you can run a
different program or display a different file. You can move windows around the display
screen, and change their shape and size at will.
Menus: Most graphical user interfaces let you execute commands by selecting a choice from
a menu.
In addition to their visual components, graphical user interfaces also make it easier to move
data from one application to another. A true GUI includes standard formats for representing
text and graphics. Because the formats are well-defined, different programs that run under a
common GUI can share data. This makes it possible, for example, to copy a graph created by
a spreadsheet program into a document created by a word processor.
Many DOS programs include some features of GUIs, such as menus, but are not graphics
based. Such interfaces are sometimes called graphical character-based user interfaces to
distinguish them from true GUIs.
Fifth Generation of Computer:-
Fifth generation computing devices, based on artificial
intelligence, are still in development, though there are some applications, such as voice
recognition, that are being used today. The use of parallel processing and superconductors is
helping to make artificial intelligence a reality.
Artificial intelligence includes the following areas of specialization:-
Games playing: programming computers to play games against human opponents.
Expert systems: programming computers to make decisions in real-life situations (for
example, some expert systems help doctors diagnose diseases based on symptoms).
Natural language: programming computers to understand natural human languages.
Neural networks: Systems that simulate intelligence by attempting to reproduce the types of
physical connections that occur in animal brains.
Robotics: programming computers to see and hear and react to other sensory stimuli.
Natural Language and Voice Recognition:-Natural-language processing offers the
greatest potential rewards because it would allow people to interact with computers without
needing any specialized knowledge. You could simply walk up to a computer and talk to it.

4. Unfortunately, programming computers to understand natural languages has proved to be
more difficult than originally thought. Some rudimentary translation systems that translate
from one human language to another are in existence, but they are not nearly as good as
human translators. There are also voice recognition systems that can convert spoken sounds
into written words, but they do not understand what they are writing; they simply take
dictation. Even these systems are quite limited -- you must speak slowly and distinctly.
Most Popular Desktop Operating Systems:-
The three most popular types of operating systems for personal and business computing
include Linux, Windows and Mac.
Windows:-
Microsoft Windows is a family of operating systems for personal and business computers.
Windows dominates the personal computer world, offering a graphical user interface (GUI),
virtual memory management, multitasking, and support for many peripheral devices.
Mac
Mac OS is the official name of the Apple Macintosh operating system. Mac OS features a
graphical user interface (GUI) that utilizes windows, icons, and all applications that run on a
Macintosh computer have a similar user interface.
Linux
Linux is a freely distributed open source operating system that runs on a number of hardware
platforms. The Linux kernel was developed mainly by Linus Torvalds and it is based on
UNIX.
According to Netmarketshare.com, the most used desktop operating system and
versions used on PCs in July 2017 are:-
Windows 7 (48.91%)
Windows 10 (27.63%)
Windows 8.1 (6.48%)
Windows XP (6.10%)
Mac OS X 10.12 (3.52%)
Linux (2.53%)
Windows 8 (1.42%)
Mac OS X 10.11 (1.17%)
Mac OS X 10.10 (0.76%)