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What is a computer?
One of the first things that we have to do is define a computer. Before we look under the hood we have to know what we are looking at. We will define a computer as a programmable machine that receives input, stores and manipulates data, provides output in different formats. You can use a computer to type documents, send email, and browse the internet. You can also use it to handle spreadsheets, accounting, database management, presentations, games, and more.
Different Types of Computers
When most people hear the word "computer" they think of a personal computer such as a desktop or laptop computer. However, computers come in many shapes and sizes, and they perform many different functions in our daily lives. When you withdraw cash from an ATM, scan groceries at the store, or use a calculator, you're using a type of computer.
Computers can be categorized into two types:
General Purpose Computers
A general-purpose computer is one that, given the appropriate application and required time, should be able to perform most common computing tasks. Most computers in use today are General-Purpose computers — those built for a great variety of processing jobs. They are designed to perform a wide variety of functions and operations. The most common general purpose computers:
Desktop Computers
Many people use desktop computers at work, home, school, or the library. They can be small, medium, or large in style, and usually sit on a desk. Once you add a monitor, mouse, and a keyboard, you have what is typically known as a desktop computer. Most desktop computers are easy to upgrade and expand, or add new parts. Another benefit of desktop computers is the cost. If you compare a desktop and a laptop with the same features, you will most likely find that the desktop computer is priced lower. Some desktop computers have a built-in monitor to save space. These are often called all-in-one desktop computers. A Laptop Computer The second type of computer that you may be familiar with is a laptop computer, or laptops as they are often referred to. Laptops are battery or AC-powered personal computers that are more portable than desktop computers, allowing you to use them almost anywhere. Since a laptop is smaller than a desktop, it's more difficult to access the internal components. That means you may not be able to upgrade them as much as a desktop. However, it's usually possible to add more RAM or a bigger hard drive. A laptop computer is sometimes called a notebook computer because of its size. Servers A server is a computer that "serves up" information to other computers on a network. Many businesses have file servers that employees can use to store and share files. A server can look like a regular desktop computer, or it can be much larger. Servers also play an important role in making the internet work: they are where web pages are stored. When you use your browser to click a link, a web server delivers the page you requested. Special Purpose Computers
Today, there lots of everyday devices that are basically specialized computers, even though we don't always think of them as computers. A special-purpose computer is designed to be task specific and most of the times their job is to solve one particular problem. They are also known as dedicated computers, because they are dedicated to perform a single task over and over again.
While a special purpose computer may have many of the same features found in a general purpose computer, its applicability to a particular problem is a function of its design rather than to a stored program. The instructions that control it are built directly into the computer, which makes for a more efficient and effective operation. They perform only one function and therefore cut down on the amount of memory needed and also the amount of information which can be input into them. As these computers have to perform only one task, therefore, they are fast in processing. A drawback of this specialization, however, is the computer’s lack of versatility. It cannot be used to perform other operations. Here are a few common examples:
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