July 3, 2008


Ametropolitan area network(MAN) IS A NETWORK THAT INTERCONNECT USERA WITH COMPUTER RESOURCES IN A GEOGRAPICAL AREA OR REGION larger than that coverd by a wide area network(WAN).The term is applied to the interconnection of networks in a city into a single larger network.It is also used to mean the interconnection of several local area networks by bridging them with backbone lines.The latter usage is also sometims reffered to as a campus network.EXAMPLES ofmetropolitan area networks of various sizes can be found in the metropolitan areas of lahore,karachi,gujranwala.Large universities also sometimes use the term to describes their networks.A recent trend id the intallation of wireless MANs. Metropolitan Area Network (MAN) is a large computer network that spans a metopolitan area or campus. Its geographic scope falls between a WAN and LAN. MAns provide Internet connectivity for LANs in a metropolitan region, and connect them to wider area networks like the Internet.

July 2, 2008


A wide area network is a digital communication system,which interconnects different sites,computer installation and user terminal and may also enable LANs to communicate with each other.this type of communication network may be developed tooperate nationwide or worldwide.In a WAN the trensmission medium used are normally public system such as telephone lines,microwave anWANs [a] are used to connect LANs and other types of networks together, so that users and computers in one location can communicate with users and computers in other locations. Many WANs are built for one particular organization and are private. Others, built by Internet service providers, provide connections from an organization's LAN to the Internet. WANs are often built using leased lines. At each end of the leased line, a router connects to the LAN on one side and a hub within the WAN on the other. Leased lines can be very expensive. Instead of using leased lines, WANs can also be built using less costly circuit switching or packet switching methods. Network protocols including TCP/IPdeliver transport and addressing functions. Protocols including Packet over SONET/SDH, MPLS, ATM and Frame relay are often used by service providers to deliver the links that are used in WANs. X.25 was an important early WAN protocol, and is often considered to be the "grandfather" of Frame Relay as many of the underlying protocols and functions of X.25 are still in use today (with upgrades) by Frame Relay.d satelite.


A network is a digital communication system capable of interconnecting a large number of computer, terminal and other peripheral devices within a limited geographical area.lan naomally operate within a limited area such as an office building or a compus is owned by the using orqanization.The configuration of a lan can be star, a ring or simply devices attached along a length of cable .In lan trasmission,channals generally use coaxial or fiber optic cables and special interfece units rather than telephone lines anmodems .A network is a computer network covering a small geographic area, like a home, office, or group of buildings e.g. a school. The defining characteristics of LANs, in contrast to wide-area networks , include their much higher data-transfer rates, smaller geographic range, and lack of a need for leased telecommunication lines.The first LAN put into service occurred in 1964 at the Livermore Laboratory to support atomic weapons research. LANs spread to the public sector in the late 1970s and were used to create high-speed links between several large central computers at one site. Of many competing systems created at this time, Ethernet and ARCNET were the most popular.


Each time we use the phone,weuse use the world largest telecommnication network or the telephone system.A telephone is an endpoint or a node,connected to a computer to a network of telephone that routs your voice signals to anyone of the 500 million telephone in the world.Computer network can be defined as The combination of two or more computer in such a way that they can share the resources of each other.Computer networks may be classified according to the scale: Personal area network (PAN), Local Area Network(LAN), Campus AreaNetwork (CAN), Metropolitan area network (MAN), or Wide area network(WAN).
As Ethernet increasingly is the standard interface for networks, these distinctions are more important to the network administrator than the user. Network administrators may have to tune the network, to correct delay issuComputer networks can also be classified according to the hardware technology that is used to connect the individual devices in the network such as Optical fibre, Ethernet, Wireless LAN, HomePNA, or Power line communication.
Ethernets use physical wiring to connect devices. Often they employ hubs, switches, bridges, and/or routers.
Wireless LAN technology is built to connect devices without wiring. These devices use a radio frequency to connectes and achieve the desired performance level.


In information society the focus of commerce is on the generation of information.Atechnological revolution ischarging our ways of life. the way we live work play.Computer is changing the ways we communicate,do business and learn about the different branches ofeducation.Knowledge is nowadays more accessible due to advancement in computer technology.we can defined as computer system.The computer is derived from the world compute which means to calculate.so acomputer isnormally considered to beacalculating device that can perform arith matic and logical operation at a very fast speed.OR A computer is an electronic device that can accept data, process it and give result after
thatprocessin.Input/data processing output/result.The computer revolution is transforming the way we communication ,do bussiness,and learnThis technological revolution is having a profound impact on the business community and on our private and professional lives.Businessman is now relying on computer to keep the documents in soft form.In this way he is very comfortable to keep them where ever he go and confident on the reliability of the documents.Computer are also widely used in industry for research and manufacturing.Scientists use computer as a tool in experimentation,design and development.There are a lot of tools used for this purpose.We can store data in a computer and retrieve stored data when we needed.We can send message to our friend,relatives and family anywhere in the world by connecting computer with internet.Computer technology can be used in performing differnt routine tasks in office.Computer can play very vital role in the advancement of secience and tecnology.computer can also use all field of life.


Analog quanties shows the continuity of a specied value.Analog computer are devices, which are used to measure continuous value.it example is a theremeter because it measure the length of amercurry column,which varies continuously.second example is analog colock.these computer so big. these computer can help the student.The problem under study is described with a set of mathematical equations or, when that is not possible, the system configuration and the interrelations of component influences are defined in block-diagram form, with each block described in terms of black-box in.these computer is run to solve the equations or simulate the black boxes so that the resultant values or system responses can be obtained. This gives the initial answers and the “feel” for the systemput-output relationships.
DIGITAL means discrete.with digital signals everything is described in two either on or off.digital computer has two state.0and1.
The basic concepts involved in using a digital
TELEPRINTer,semituneous equations
Simple autocode examples
Examples of working advanced design programmes.digital computer has more many types.
A computerthat combines the features of both analog and digital computer system is known as hybired computer.An example of a hybrid computer system is acement pln where all calculatoain are made by digita computer system and accordi ng ideas and action such as increase of certain material in furnace and increase/decrease of fuel for tempereture is performed by the help of analog system. Hybrid computers can be used to obtain a very good but relatively imprecise seed' value, using an analog computer front-end, which is then fed into a digital computer iterative process to achieve the final desired degree of precision. With a three or four digit, highly accurate numerical seed, the total digital computation time necessary to reach the desired precision is dramatically reduced, since many fewer iterations are required.
THESE COMPUTER ARE THE LARGEST,FASTER,AND THE MOST EXPENSIVE COMPUTER SYSTEMIN THEWORLD.THEY ARE USED TO PROCESS COMPLEX SCIENTIFIC JOBS.these computer based on the concept of parrellprocessing.very few companies in the world produce super computer.cray rearch andeta system inc.super somputer are widly used in meteorological offices where weather patterns are predicated by manipluting vast amounts of data.Supercomputers introduced in the 1960s.
These computer are the large large computer available in different models.size,and price.qualified operate and programming required,they support a wide range of pripherals.they have a large storage capcity,they can make use of awide variety of software.Large computer supporting typically 100 to 500 users at a time. The IBM 370 and IBM 3081 are examples of mainframe computers.Today in practice, the term usually refers to computers compatible with the IBM System/360 line, first introduced in 1965. (IBM System z9 is IBM's latest incarnation.) Otherwise, systems with similar functionality but not based on the IBM System/360are referred to as "servers" However, "server" and "mainframe" are not synonymous (see clientserver.
MINICOMPUTER WERE INTRODUCED IN THE 1960S.THEY HAVE LESS CAPACITY.They offer a limited range of peripherals.limited software can be used.air condition is not necessary for minicomputers.Medium-capacity computer that is larger than a microcomputer but smaller than most mainframes. A minicomputer can handle a larger amount of data than a microcomputer and can perform most of the functions of a mainframe.
A mid-sized computer, usually fitting within a single cabinet about the size of a refrigerator, that has less memory than a mainframe.
These computer are widly used nowdays commonly and these computer.they are very cheaper and small.they have limited input output caacities. low storage.they designeg to be used by one person at a time.these computer are widley used in bussiness application.these computer are used for engineering designs.micro computer can also be used for play music and communication.The earliest models often sold as kits to be assembled by the user, and came with as little as 256 bytesof RAMand no input/outputdevices other than indicator lights and switches. However, as microprocessors and semiconductor memory became less expensive from the early-to-mid-1970s onwards, microcomputers in turn grew faster and cheaper. This resulted in an explosion in their popularity during the late 1970s and early 1980s.
These computer are also known as personal computer.they are usually single user machines but can be interconnected.They are cheaper and have been sold in millions.
A computer is a small mobile prsonal computer, usually weighing from on to three kilograms, depends on size, material and other factor.While the term laptop and note book are often used interchaneably laptop is the older term introduced in 1983.note book computer system very cheaper and small in size laptop usually run on a single battery or from an external AC/DC adapter which can charge the battery while also supplying the computer itself.
A small computer that literally fits in your plam.Compared to full size computer, plamtop are severely limited, but they are pratical for certain function such as phone book and calendars.Plamtop that use a pen rather than a keyboard for input are often called hand held computer or PDAs(Personal Digital Assistant).small in size.Most plamtop computer do not include disk drives.


First generation computer were featured by the fact that operating instruction were made to order for the specific task for which the computer was to be used.its made the computer difficult to program and limited its versatility and speed.features are first generation computersuch as vacum tube, operating instruction.machine language.EXAMPLE eniace.edvac,edsac,etc.vaccum tubes were the only electronic components available during those days.disadvantages.unreliable,air condition,prone to frequent hardware failure,non portable,limited commercial use.

In 1984 invention of transistors,vacum tubes were replaced with transistors. second generation computer replaced machine language with assembly language allowing abberviated programming codes to replace long difficult binary codes.EXAMPLE lilliac,ibm 7090,608.advantage.small size,more reliable less heat,less hardware failure, better then first generation computer.disadvantages.air condition required,frequent maintaince required.

Third GENERATION COMPUTER.(1964-1975).
The invention of the silicon ic by rober noyce in 1958 allowed dozen of transistors to be put on a single chip.its packing made it possible to builed computer that were smaller,fasterand cheaper.Another third deneration development included the use of an operating system that allowed machine to run many different programs at once with central program that mentioned and coordinated the computers memory.EXAMPLE.ibm 360,cdc6600.advantages.small size,reliable,working speed faster these computer maintaince cost was low.easy movable.very cheaper. diaadvantages.air condition required, highly difficulty technology required.

FOURTH GENERATION COMPUTER.(1975-present).Bys the 1980 very large scale integration squeezed hundered of thousands of components onto a chip.altra large scale integration (ulsi) .its inreased their power,efficiencyand reliability,Intel made a chip named4004 in 1971 on which a central processing unit ,memory and input output controls were made.IBMintroduced its prsonal computer for use in 1981.As smaller computer became more powerful,they could be linked togathered or networked share memory space,software information.computer was linked together by using either direct writing called a local area network.EXAMPLESintel4004,xt,4x86,pentium,1,2,3,4.advantages,small in size.reliable.heat generation is low.no aie condition required,bog memory,easily portable.

FIFTH GENERATION COMPUTER.(present-beyond).The most frequent famous example of fifth generation computer is the fictional hal 9000 from arthur cclarkes noval 2001 a spase odyssey.hal could reason well enough to hold conversation with its human operators use visual input and learn from its own experience. using recent engineering advance,computer is able to accept spoken word instruction and reproduce human reasoning.for example expert system assist dostors in making diagnoses by applying the problem solving steps.hal 9000.

July 1, 2008


The first device that qualifies as a computer is the abacus.The abacus was introduce 5,000 years in asia minor.This device allows user to calculate by sliding beads arranged on a rack.abacus is the brief history of and a Bibliography follows. It is a good idea to think about the history of arithmetic, mathabacus is a device, writing and records information. abacus usually of wood having a frame that holds rods with freely-sliding beads mounted on them."2
Chinese abacus has 2 beads in the top position over the horizontal bar and 5 beads in the lower position, for each "column". The upper row beads could each represent one hand. The lower columns could represent the 10 fingers.

This picture of a black colored abacus shows an abacus with more depth to it than in the previousphotograph.
Jhon napier.
john napier was a scottish mathematication.after abacus he was made first manual calculating device.in addition to multiplication this machine was also used to calculate square roots and cube roots.

Blaise pascal.
In 1642 blaise pascal the 18 year old son of french tax collector introduced a numeric wheel calculator to help his father in calculation. its device was known as pascaline.
Barron gottfried wilhelm von leibniz.
In 1694 a german philosopher and mathematician made some improments in pascal smachine.He added the characteristics of multiplation and division. The machine was able to perform these operation by using repeated addition and subtaction.
Charles xavier thomos de colmar.
A frenchman introduced a machine in 1820 that could perform the foue basis arithmetic function.
charles babbage.
An english mathematician, proffeser made a differenceengine in 1833 which was powered by steam to solve mathematical equation.After ten years in 1842 he made a generalpurpose computer named analytical engine.its analytical engine could add, subtract, multiply and divide in automatic sequence at a rate 60 addition per second.
joseph marie jacquarad.
In 1801 a french silk weaver and inventor joseph marie jacquared introduced the jacquared loom.jacqquareds loom was conrolled by the recorded patterns of holees a string of cards.
George boole.
Georage boole clarified binary system of algebra,which stated that any mathematical equation could be stated simply as either true or false.

Herman Hollerith
In 1890, an america inventor herman hollerith applied the action or idea of punch boards in the form of punch cards in computer for input and output.He invented apunch card labulating machine.