Computer, electronic device that can receive a set of instructions, or program, and then carry out this program by performing calculations on numerical data or by manipulating other forms of information.
The central processing unit
The CPU may be a single chip or a series of chips that perform arithmetic and logical calculations and control the operations of the other elements of the system.
Motherboard
A motherboard is a printed circuit board that contains a computer's principal components. These components usually include a microprocessor, memory chips, communication ports, and a disk controller.
Network Configurations
A star network connects many computers and computer resources, such as a printer, to a central computer called a server, which directs the flow of information. A token ring network uses a special message called a token that travels from computer to computer. The token designates which computer sends information through the network.
Computer Networks, the widespread sharing of information among groups of computers and their users, a central part of the information age. The popular adoption of the personal computer (PC) and the local area network (LAN) during the 1980s has led to the capacity to access information on a distant database; download an application from overseas; send a message to a friend in a different country; and share files with a colleague—all from a personal computer.
The networks that allow all this to be done so easily are sophisticated and complex entities. They rely for their effectiveness on many cooperating components. The design and deployment of the worldwide computer network can be viewed as one of the great technological wonders of recent decades.
LOCAL AREA NETWORKS
One of the most dramatic events in computer networking has been the introduction and rapid growth of the local area network (LAN) as a way to standardize the system of linking computers used in office systems. As the name suggests, this is a means of connecting a number of computing elements together. At the simplest level, a LAN provides no more than a shared medium (such as a coaxial cable to which all computers and printers are connected) along with a set of rules that govern the access to that medium. The most widely used LAN, Ethernet, uses a mechanism called Call Sense Multiple Access—Collision Detect (CSMS-CD). This means that each connected device can only use the cable when it has established that no other device is using it. If there is contention, the device looking for a connection backs off and tries again later. The Ethernet transfers data at 10M bits/sec—which is fast enough to make the distance between devices insignificant. They appear to be connected directly to their destination.
Open Systems
An operating system is a master control program that interprets user commands. It controls all the communications between different parts of the system
This term covers the general aim of building computer systems so that they can readily be interconnected, and hence distributed. In practice, open systems is all about unbundling all the complexities of a computer system and using similar structure across different systems. And this entails a mixture of standards (which tell the manufacturers what they should be doing) and consortia (groups of like-minded people who help them to do it). The overall effect is that they can talk to each other.
The ultimate aim of all of the work in distributed systems is to allow anyone to buy computers from a number of different manufacturers, to site them wherever is convenient, to use broadband connections to link them, and to operate them as one cooperating machine that takes full advantage of the fast links.
