What is monitor and kinds of monitor?

Monitor is the most common output device of computer which enables and desplays all sort of information and data on screens.

There are two types of monitor.

1. CRT MONITORS

2. LCD MONITORS

CRT MONITORS (cathode ray tube):

Near the back of a monitor’s housing is an electron gun. The gun shoots a beam of electrons through magnetic coil which aims the beam at the front of monitor .the back of the monitor is coated with phosphors, chemicals that glow when they are struck by the electron beam. The screen phosphor coating is organized into grid of dots. The smallest dot of phosphor that the gun can focus on is called pixel

LCD MONITOR (LIQUID CRYSTAL DESPLAY)

LCD stands for liquid crystal display, refer to the technology behind this. Flat panel monitor LCD monitor is distinguishable from the CRT MONITOR by several ways such as the CRT monitor is width depth of several inches and weight (30-50 inch) and (13-23) kg. While LCDs are commonly 1-3 inch width and weight (4.5)kg.

LCD MONITOR consists of five layers.

1. Backlight

2. Sheet of polarized glass

3. Mask of colour pixel

4. Layer of liquid crystal

5. A second sheet of polarized glass.

There by allowing the degree of light that has passed through specific coloured pixels to illuminate the screen by creating pictures.

( Extra Reading about LCD )

LCD stands for Liquid Crystal Display, referring to the technology behind these popular flat panel monitors. An LCD monitor is distinguishable from a traditional CRT monitor as the latter has a bulky footprint with a depth of several inches and a weight of 30 - 50 pounds (13 - 23 kilograms) or more, while LCDs are commonly 1 - 3 inches (2.5 - 7.5 cm) thick and weigh less than 10 pounds (4.5 k).

LCD displays were used on laptop computers before the technology improved enough to make the jump to desktop monitors. An LCD monitor consists of five layers: a backlight, a sheet of polarized glass, a "mask" of colored pixels, a layer of liquid crystal solution responsive to a wired grid of x, y coordinates, and a second polarized sheet of glass. By manipulating the orientations of crystals through precise electrical charges of varying degrees and voltages, the crystals act like tiny shutters, opening or closing in response to the stimulus, thereby allowing degrees of light that have passed through specific colored pixels to illuminate the screen, creating a picture.

As LCD technology evolves, different techniques for producing color emerge. Active-matrix or TFT (thin film transistor) technology produces color and images as sharp as any CRT and is generally considered superior to passive-matrix technologies.

Important specifications to consider when shopping for an LCD monitor include contrast ratio, brightness (or "nits"), viewing angle, and response time.

Contrast ratio relates to the display's comparative difference between its brightest white values and its darkest black values. A higher contrast ratio will have truer colors with less "wash out." The standard offering for lower end models is commonly 350:1. Many experts recommend a contrast ratio of 500:1 or better.

An LCD monitor is brighter than a CRT, giving the consumer little reason to hunt for an especially bright model. Brightness is measured in nits, or one candela per square meter. Anywhere from 250 - 300 nits is standard. If the nits are much higher you'll likely end up adjusting the brightness way down.

The viewing angle is an especially important consideration if you plan to have multiple people viewing the LCD monitor at any given time. There is a vertical and a horizontal viewing angle specification, which refers to the degree you can stray from dead center before the picture starts to wash out. High contrast levels usually go hand-in-hand with wider viewing angles. Many recommend a viewing angle of at least 140 degrees horizontal and 120 degrees vertical. The wider the viewing angles, the better.

Response time is measured in milliseconds (ms) and refers to how long it takes pixels to turn from completely white to black and back again. Smaller values represent a faster response time and are more desirable, especially for gaming or viewing video. If the response time is slow, "ghosting" or "trailing" can occur with fast-moving images, as repaints of the screen overlap. A maximum response time should be no more than 25ms for general use, and 17ms is better. Many gamers report no ghosting using an LCD monitor with a response time of 16ms or less.

LCDs use only one-third to one-half the electricity of their CRT counterparts. They are much easier on the eyes, take up 90% less space, and only weigh a few pounds. They also emit far less low-frequency radiation than CRTs. This makes LCDs a great choice for nearly everyone, and ideal for people who work all day in front of the screen. Colors may change hue as one moves to the outer limits of the viewing angle, particularly on displays with narrow viewing angles and low contrast ratios. For this reason graphics professionals that require exacting color consistency regardless of viewing angle generally use CRTs, though LCDs have improved in this regard.

An LCD monitor comes in standard sizes from 15-inches to 21-inches, and larger. The viewing screen is the same size as the rated display, unlike CRT monitors. Therefore a 15-inch LCD will have a 15-inch viewing screen.

A potential weak link of an LCD monitor is the backlight. Many monitors come with a 3-year warranty, but stipulate 1 year for the backlight. Models with 3-year warranties that cover the backlight usually cost a little more but may be worth the extra investment.

What is networking and what are the kinds of networking?

Networking is a set of technologies hardware, software and media that can be used to connect computers together, enabling them to communicate and share information and also share resources in real time.

There are several types or kinds of networking but the most common types are as follow

1. Local area networking (LAN)

2. Wide area networks (WAN)

3. HOME AREA NETWORK (HAN)

4. METROPOLITAN AREA NETWORK (MAN)

5. CAMPUS AREA NETWORK (CAN)

WHAT IS LAN OR LOCAL AREA NETWORK?

Local area network is a data communication system consisting of several devices .this type of network contains computers which are nearly located to each other and connected by cable. Local area network can connect more than two computers it may be two or three even a hundreds of computer in same area.

WHAT IS WIDE AREA NETWORK?

Wide area network is generally the connection of two LANs or more than tow LANs across a wide geographical area. Such as a company may have its headquarters in wide areas .they make a wide area network.

Network topologies

The logical layout of the cables to and devices that connect the nodes of the network is known as topology. There are four topologies

1. Bus topology

2. Star topology

3. Ring topology

4. Mesh topology

Bust topology

Bust topology networks using one cable all the nodes and other devices are connected in series to the cable line. A special device called terminator is attached to the start and at the end of line in order to stop the network signals so they do not bounce down the cable.

Star topology network is the most common topology in a star network all the nodes are connected to device which is called hub and communicate through it

Ring topology

The ring topology connects the nodes in circular chain, with each node connected to the next. The last node connects to the first, completing the ring. each node examines data as it travels.

Mesh topology

Mesh topology is the least used topology and most expensive topology network to implement. In mesh topology environment the a cable runs from every computer to every other computer. If you have four computers you must have six cables to make mesh topology network system.

What is hub?

Hub is an affordable connection point for different types of devices on a network. It basically transfers packets that it receives from all nodes.

What is bridge?

A bridge is a device that connect two LANs or two segments of LANs . abridge looks after each packet that carries information.

What is switch?

Switch is a device that learns which machine is connected to its port by using the pc, printer, or other devices’ IP address.

What is router?

A router is complicated device that stores the routing information for networks. A router looks after each packet carrying the information to determine where each packet to go.