Tuesday, September 16, 2008

types of computer

Desktop Computer
A desktop computer is an independent personal computer (PC), as opposed to smaller forms of PCs, such as a mobile laptopy indi. Today the phrase usuall cates a particular style of computer case. Desktop computers come in a variety of styles ranging from large vertical tower cases to small form factor models that can be tucked behind an LCD monitor. Prior to the wide spread of PCs a computer that could fit on a desk was considered remarkably small. In this sense, the term 'desktop' refers specifically to a horizontally-oriented case, usually intended to have the display screen placed on top to save space on the desk top. Most modern desktop computers have separate screens and keyboards.
A subtype of desktops, called nettops, was introduced by Intel in February 2008 to describe low-cost, lean-function, desktop computers. A similar subtype of laptops (or notebooks) are the netbooks.
laptop computer or simply laptop, also called a notebook computer or sometimes a notebook, is a small personal computer designed for mobility. Most laptops contain batteries to facilitate operation without a readily available electrical outlet. In the interest of saving power, weight and space, they usually share RAM with the video channel, slowing their performance compared to an equivalent desktop machine. Usually all of the interface hardware needed to operate the laptop, such as parallel and serial ports, graphics card, sound channel, etc., are built in to a single unit.
PCs are small portable computers in a "clamshell" design, that are designed specifically for wireless communication and access to the Internet. They are generally much lighter and cheaper than subnotebooks, and have a smaller display
Tablet PC
A tablet PC is a notebook or slate-shaped mobile computer, first introduced by Pen computing in the early 90s with their PenGo Tablet Computer and popularized by Microsoft. Its touchscreen or graphics tablet/screen hybrid technology allows the user to operate the computer with a stylus or digital pen, or a fingertip, instead of a keyboard or mouse

history of computer

It is difficult to identify any one device as the earliest computer, partly because the term "computer" has been subject to varying interpretations over time. Originally, the term "computer" referred to a person who performed numerical calculations (a human computer), often with the aid of a mechanical calculating device.
The history of the modern computer begins with two separate technologies - that of automated calculation and that of programmability.
Examples of early mechanical calculating devices included the abacus, the slide rule and arguably the astrolabe and the Antikythera mechanism (which dates from about 150-100 BC). Hero of Alexandria (c. 10–70 AD) built a mechanical theater which performed a play lasting 10 minutes and was operated by a complex system of ropes and drums that might be considered to be a means of deciding which parts of the mechanism performed which actions and when. This is the essence of programmability.
It was the fusion of automatic calculation with programmability that produced the first recognizable computers. In 1837, Charles Babbage was the first to conceptualize and design a fully programmable mechanical computer that he called "The Analytical Engine". Due to limited finances, and an inability to resist tinkering with the design, Babbage never actually built his Analytical Engine

How computers work

Main articles: Central processing unit and Microprocessor
A general purpose computer has four main sections: the arithmetic and logic unit (ALU), the control unit, the memory, and the input and output devices (collectively termed I/O). These parts are interconnected by busses, often made of groups of wires.
The control unit, ALU, registers, and basic I/O (and often other hardware closely linked with these) are collectively known as a central processing unit (CPU). Early CPUs were composed of many separate components but since the mid-1970s CPUs have typically been constructed on a single integrated circuit called a microprocessor.

what is computer

A general-purpose machine that processes data according to a set of instructions that are stored internally either temporarily or permanently. The computer and all equipment attached to it are called hardware. The instructions that tell it what to do are called "software." A set of instructions that perform a particular task is called a "program" or "software program."

computer training

Computer training services are where a student learns by executing special training programs on a computer relating to their occupation. is especially effective for training people to use computer applications because the program can be integrated with the applications so that students can practice using the application as they learn. Historically, growth has been hampered by the enormous resources required: human resources to create a program, and hardware resources needed to run it. Web-based training frequently includes interactive methods, such as bulletin boards, chat rooms, instant messaging, videoconferencing, and discussion threads. However, the increase in PC computing power, and especially the growing prevalence of computers equipped with CD-ROMs, is making a more viable option for corporations and individuals alike. Many PC applications now come with some modest form of often called a tutorial Web based training is usually a self-paced learning medium though some systems allow for online testing and evaluation at specific times. Web-based training (WBT) is a type of training that is similar to however, it is delivered over the Internet using a web browser..