programmable machine. The two principal characteristics of a computer are:

  • It responds to a specific set of instructions in a well-defined manner.

    •           Modern computers are electronic and digital. The actual           machinery -- wires, transistors, and circuits -- is called           hardware; the instructions and data are  called                        software.

    All general-purpose computers require the following hardware components:

  • memory : Enables a computer to store, at least temporarily, data and programs.
  • mass storage device : Allows a computer to permanently retain large amounts of data. Common mass storage devices include disk drives and tape drives.
  • input device : Usually a keyboard and mouse, the input device is the conduit through which data and instructions enter a computer.
  • output device : A display screen, printer, or other device that lets you see what the computer has accomplished.
  • central processing unit (CPU): The heart of the computer, this is the component that actually executes instructions.   
  • personal computer : A small, single-user computer based on a microprocessor. In addition to the microprocessor, a personal computer has a keyboard for entering data, a monitor for displaying information, and a storage device for saving data.
  • workstation : A powerful, single-user computer. A workstation is like a personal computer, but it has a more powerful microprocessor and a higher-quality monitor.
  • minicomputer : A multi-user computer capable of supporting from 10 to hundreds of users simultaneously.
  • mainframe : A powerful multi-user computer capable of supporting many hundreds or thousands of users simultaneously.
  • supercomputer : An extremely fast computer that can perform hundreds of millions of instructions per second.
  • Linux Network Administrators Guide - The Internet is now a household term in many countries. With otherwise serious people beginning to joyride along the Information Superhighway, computer networking seems to be moving toward the status of TV sets and microwave ovens. The Internet has unusually high media coverage, and social science majors are descending on Usenet newsgroups, online virtual reality environments, and the Web to conduct research on the new Internet Culture. Of course, networking has been around for a long time. Connecting computers to form local area networks has been common practice, even at small installations, and so have long-haul links using transmission lines provided by telecommunications companies. A rapidly growing conglomerate of world-wide networks has, however, made joining the global village a perfectly reasonable option for even small non-profit organizations of private computer users. Setting up an Internet host with mail and news capabilities offering dialup and ISDN access has become affordable, and the advent of DSL (Digital Subscriber Line) and Cable Modem technologies will doubtlessly continue this trend.
  • TCP/IP Tutorial and Technical Overview - The TCP/IP protocol suite has become the de facto standard for computer communications in today's networked world. The ubiquitous implementation of a specific networking standard has led to an incredible dependence on the applications enabled by it. Today, we use the TCP/IP protocols and the Internet not only for entertainment and information, but to conduct our business by performing transactions, buying and selling products, and delivering services to customers. We are continually extending the set of applications that leverage TCP/IP, thereby driving the need for further infrastructural support.
  • Introduction to Networking and Data Communications - Data Communications is the transfer of data or information between a source and a receiver. The source transmits the data and the receiver receives it. The actual generation of the information is not part of Data Communications nor is the resulting action of the information at the receiver. Data Communication is interested in the transfer of data, the method of transfer and the preservation of the data during the transfer process. In Local Area Networks, we are interested in "connectivity", connecting computers together to share resources. Even though the computers can have different disk operating systems, languages, cabling and locations, they still can communicate to one another and share resources. The purpose of Data Communications is to provide the rules and regulations that allow computers with different disk operating systems, languages, cabling and locations to share resources. The rules and regulations are called protocols and standards in Data Communications.
  • Understanding LDAP - Design and Implementation - This IBM Redbook will help you create a foundation of LDAP skills, as well as install and configure the IBM Directory Server. It is targeted at security architects and specialists who need to know the concepts and the detailed instructions for a successful LDAP implementation.