network topology is the pattern in which nodes (i.e., computers, printers, routers or other devices) are connected to a local area network(LAN) or other network via links (e.g., twisted pair copper wire cable or optical fiber cable).

There are four principal topologies used in LANs: bus, ring and star. The most widely used of these is bus, because it is employed by Ethernet, which is the dominant LAN architecture. In a bus topology all devices are connected to a central cable, called the bus or backbone. This topology is relatively inexpensive and easy to install for small networks.

In a ring topology each device is connected directly to two other devices, one on either side of it, to form a closed loop. This topology is relatively expensive and difficult to install, but it offers high bandwidth and can span large distances. A variation is the token ring, in which signals travel in only one direction around the loop, carried by a so-called token from node to node.

In a star topology all devices are connected directly to a central computer or server. Such networks are relatively easy to install and manage, but bottlenecks can occur because all data must pass through the central device.

The several basic network topologies can be combined in various ways to form hybrid topologies, such as a ring-star network or a tree network. The latter consists of two or more star networks connected to a linear bus.

The word topology comes from the Greek                                        words topos meaning place and logos meaning study. It is a description of any locality in terms of its layout. Topology is a branch of mathematics concerned with properties of geometric figures that are distorted without tearing or bonding together.


Introduction To Computing

the course CSE-145 Introduction To Computing is basically designed for the students of the university who are new in the world of computing.  this course provides the basis for all students to get involve in basic computing techniques and use of computer as a professional, rather than a device for entertainment. the word “computing” basically means to calculate, which originally performs the actions of basic mathematical operations. But unlike maths, computing techniques are now widely used in the life of all professionals in all walks of professionalism. As computer is playing an important role in all aspects of life, so basic computing knowledge is necessary for all professionals to prosper in life.

The course mainly deals with basic computing softwares and basic computing tools.There are two reasons why everyone should study computing:

1. Nearly all of the most exciting and important technologies, arts, and sciences
of today and tomorrow are driven by computing.
2. Understanding computing illuminates deep insights and questions into
the nature of our minds, our culture, and our universe

Computer science is the study of information processes. A process is a sequence of steps. Each step changes the state of the world in some small way, and the
result of all the steps produces some goal state. For example, baking a cake,
mailing a letter, and planting a tree are all processes. Because they involve physical
things like sugar and dirt, however, they are not pure information processes.
Computer science focuses on processes that involve abstract information rather
than physical things.
The boundaries between the physical world and pure information processes,
however, are often fuzzy. Real computers operate in the physical world: they
obtain input through physical means (e.g., a user pressing a key on a keyboard
that produces an electrical impulse), and produce physical outputs (e.g., an image
displayed on a screen). By focusing on abstract information, instead of the
physical ways of representing and manipulating information, we simplify computation
to its essence to better enable understanding and reasoning.

A procedure is a description of a process. A simple process can be described
just by listing the steps. The list of steps is the procedure; the act of following
them is the process. A procedure that can be followed without any thought is called a mechanical procedure. An algorithm is a mechanical procedure that is
guaranteed to eventually finish.
For example, here is a procedure for making coffee, adapted from the actual directions that come with a major coffeemaker:

1. Lift and open the coffeemaker lid.
2. Place a basket-type filter into the filter basket.
3. Add the desired amount of coffee and shake to level the coffee.
4. Fill the decanter with cold, fresh water to the desired capacity.
5. Pour the water into the water reservoir.
6. Close the lid.
7. Place the empty decanter on the warming plate.
8. Press the ON button

Describing processes by just listing steps like this has many limitations. First,
natural languages are very imprecise and ambiguous. Following the steps correctly
requires knowing lots of unstated assumptions. For example, step three
assumes the operator understands the difference between coffee grounds and
finished coffee, and can infer that this use of “coffee” refers to coffee grounds
since the end goal of this process is to make drinkable coffee. Other steps assume
the coffeemaker is plugged in and sitting on a flat surface.
One could, of course, add lots more details to our procedure and make the language
more precise than this. Even when a lot of effort is put into writing precisely
and clearly, however, natural languages such as English are inherently ambiguous.
This is why the United States tax code is 3.4 million words long, but
lawyers can still spend years arguing over what it really means.