When computers are spread over a large geographical area like intercity, intracity, across buildings etc and they still connected to one another in order to share information, then the configuration is called Wide Area Network(WAN). WAN are extensions of LANs. Two LAN’s connected by telephone lines and modems can act as WAN. A router which is special purpose computer and a network operating system is required to establish a connection. WAN, therefore enables clients to take full advantage of resource sharing as well as new practices like working alone from home, staying in closer contact with external suppliers, distributors and building links to remote branches and international offices. With this facility we can keep in contact with all those needed. The internet is an invention that changed millions around the world. It reduced the distances between people bringing in new innovations and making communication possible throughout the globe. Thus it has aided in our progress.

There are many ways of interconnecting systems in a network. The major topologies available are star, ring and bus. However there are various other topologies like hybrid topology which are not commonly used. In star configuration all the nodes are connected to a central node to form a star like picture. In bus configuration all the nodes in a LAN share the same cable and there is no centralized node. In ring configuration nodes are connected in series and form a complete ring. The data flows from one node to another which is picked by the appropriate target node. There are three major components namely medium, network interface and network software. Medium is one over which data transfer takes place. Network interface unit provides interface between LAN medium and computer hardware. Network software runs in each of the connected systems and gives network wide communication capabilities to the user. Thus it has been a major revelation.

There are three major possible ways of networking such as the LAN, WAN and MAN. Since the 1980’s LAN has gained prominence and is most commonly used. A LAN is a group of desktop computers located relatively close to each other and connected through cabling system to enable them to share access to computing resource. LAN satisfies two requirements namely sharing information and sharing computer resources. A LAN consists of PC’s on the same floor of a building or situated on different floors on the same building. It may even consist of computers which are within the factory area, but spread across various buildings like administrative block or production block or warehouse, etc. LAN consists of workstations which are connected to a central computer called file server. All workstations on LAN would have a network interface. There are various topologies available based on how the systems are connected namely the star, bus and ring topology.

A network is the means by which computers share and exchange information and resources across short or long distances. Short distance communication is called as Local Area Network(LAN) and long distance communication is known as Wide Area Network(WAN). Networking provides many advantages such as sharing of data, transfer of files, data security, less memory usage, common hardware , software resources, cost sharing and less expensive. Making the best use of networking technology is about making better use of business resources, enhancing productivity and efficiency, reducing costs and gaining competition advantage. It enables everyone in an organization to communicate with one another and share the resources as well. Networks can be designed for small office between two or ten workstations to the largest international corporations linking thousands of workstations. This concept of networking makes it possible to share devices like printers and scanners thus cutting down costs. Hence it is mandatory for better performance.

Hard disks are sealed in most cases. The technology of hard disk has changed over the period of time. The first hard disk was bulky and was not capable of holding large data. Current hard disks have capacities of 80 GB, 320 GB with speeds of more than 7200 rpm. Mini external USB hard disks have also entered the market. The interfaces currently used are IDE, SATA, SCSI and so on. The SCSI can be used to interconnect any other device besides hard disks. Also CD’s and DVD’s have become popular storage medium due to its low cost , portability and capacity. Magneto optic disks of capacity in the range of 650 MB, 4 GB and above are available. These are based on laser technology. Digital audio tapes are also a popular storage means but they have become outdated because of their lower storage capacity. These digital tapes are used for archiving purposes. The tapes which were used in earlier days for playing music is a good example for this.

The operating system helps in the proper utilization of computer resources like hardware, software and data. The operating system is the government. It cannot perform anything useful all by itself. It simply provides an environment so that all the other programs can perform useful work.  A computer system has many resources that can be used to solve a problem. CPU time, memory space, file storage space, input or output devices and so on. The OS acts as the manager of these resources and allocates them to specific programs and users as necessary. The operating system must decide which requests are essential resources to operate the computer system efficiently and fairly. Then there is also the control program which controls the execution of user programs to prevent errors and improper use it in computer. It controls multimedia programming, multi processing and time sharing module. The Windows OS from Microsoft is not platform independent but it is more commonly used because of its ease of use. Linux solves this problem.

The fourth generation micro  computers like the IBM and Apple’s Macintosh are small desktop system with a floppy drive or CD drive or both. It employs a micro processor RAM, expansion slots ,slot for internal modem and functions under various operating systems. Essentially a micro computer consists of a system unit , the keyboard, mouse, CD drive, modem and Visual Display Unit. The printer is an auxillary unit to get an output and scanner to input data. Operating system is an organized collection of routines and procedures for operating a computer. It acts as an intermediary between a computer and the computer hardware. The basic purpose of the OS is to provide an environment in which a user can execute programs. It is used to make the computer easier to operate. It also makes efficient use of computer hardware. Some examples of operating systems are Windows, DOS, UNIX, etc.

Bursting is another time saving technology. The purpose of bursting is to provide the CPU with additional data from the memory based on the need. Instead of the CPU retrieving information from memory one piece at a time it grabs a block of information from several consecutive addresses in memory. Pipelining is a computer processing technique where a task is divided into a series of stages with some part of work completed in every stage. Through the division of larger work into smaller sub parts  that are overlapping it is possible to improve the performance that is impossible in non pipelined processing. The easiest way to categorize memory is by form factor. It describes the pin sizes and configuration. Almost every computer system has memory sockets that accept only one form factor. Sometimes computer systems are designed with the provision of recognizing more than one form factor. These designs are transitory in nature and hence one cannot be sure which will be the best at a particular period of time.

The term interleaving refers to a process in which the CPU alternates communication between two or more memory banks. Every time the CPU addresses a memory bank, the bank needs about one clock cycle to reset itself. The CPU saves processing time by addressing a second bank while the first bank is reset. It improves the performance of the system by a considerable amount. The placement of memory modules on the system board has direct effect on the performance of the system. Since local memory holds all the vital data that the CPU needs for processing, the speed at which the data travels between memory and CPU affects overall system performance. The exchange of information between the CPU memory and processor are intricately timed so as to maximize performance by utilizing faster data transfer rates. Hence all the components must be laid out as close as possible to maximize speeds.

Cache memory is a relatively small amount of high speed memory that resides very close to the CPU. It supplies the CPU with the most frequently requested data and instructions. This is because retrieving information from the cache memory takes a fraction of time lesser when compared to that taken from main memory. Thus it saves a lot of time. Most of the cache memory  is incorporated into the processor chip itself. But other means such as on the motherboard or a cache socket near CPU are also possible. Cache components are assigned levels based on how close they work with the processor.  For simple example a cache labeled level one is closest to the computer. Level 2 comes next and so on. Computers also have other types of caching other than cache memory. Sometimes main memory is used as cache for hard drive. Thus the term cache refers to all storage technologies used and not specifically just a memory.