Although computers come in a variety of sizes and shapes, the basic components required to complete the information processing cycle must be present in them all. There are four basic types of computers: supercomputers, mainframes, minicomputers, and microcomputers:
Supercomputers are large, powerful computers typically devoted to specialized tasks. You might have heard of Big Blue, the IBM supercomputer that challenged chess players to chess matchesand beat them! Supercomputers are the fastest and most expensive of all computers. They perform sophisticated mathematical calculations, track weather patterns, monitor satellites, and perform other complex, dedicated tasks.
Mainframe computers are large computers often found in businesses and colleges, where thousands of people use the computer to process data. Mainframe computers multitask; that is, they can perform more than one task at the same time. This capability is one of the primary ways mainframes differ from supercomputers. Mainframes can store vast amounts of data using a variety of storage devices. Early mainframe computers were very large and required separate rooms to house them. Today's mainframe computers are significantly smaller.
Minicomputers may be used in medium-sized businesses that have smaller data storage requirements than businesses using mainframe computers. Because of the increased capabilities of microcomputers, minicomputers are less common now.
Microcomputers are the smallest of the four categories of computers and the one that most people typically use. Within the microcomputer category, computers range in size from servers that have the storage capability of minicomputers (and small mainframes) to handheld devices that fit in your pocket. Some of the most common types of microcomputers include the following:
- Desktop computers sit on your desktop, floor, table, or other flat surface and have a detachable keyboard, mouse, monitor, and other pieces of equipment. Desktop computers generally fall into two main categories: PCs or Macs. The PC, or personal computer, originally referred to the IBM personal computer, but is now manufactured by a variety of companies including Hewlett-Packard, Dell, and Gateway, just to name a few. The Apple Macintosh computer, or Mac, can perform the same functions as the PC. There has been a long-running argument among computer users about which is betterPC or Mac? In reality, there are pros and cons to both types of computers, although both are good systems and the choice usually comes down to personal preference. The primary differences between the PC and the Mac relate to the different microprocessors and operating systems each one uses. The PC is typically used in a Microsoft Windows operating environment, and the Macintosh uses the Mac operating system. Although the PC and the Mac each process information differently, both can perform the same types of tasks. The PC has a larger market share among general computer users and in business settings, while the Mac is extremely popular with graphic design professionals.
- Notebook computers give users the ability to take their computers with them, making their information portable or mobile. Originally referred to as laptops, this term is slowly being phased-out in favor of the more appropriate notebook designation. Although smaller than a desktop, notebook computers are not meant to be used on your lap. If you hold one on your lap for a few minutes, you can feel the heat they generate. Notebooks are designed to be portable and can be used in a variety of places. Averaging around 6 pounds, a notebook's size and weight can also limit its computing power. Notebooks typically have a built-in monitor screen, a keyboard, and a pointing device, although it is possible to connect them to detachable devices for more comfortable desktop use.
- Tablet computers might seem similar to notebooks at first glance; however, they have some special features that set them apart. Tablet computers weigh less than notebooks, averaging about 3 pounds. They also have a convertible screen that swivels, allowing the tablet to be used like a standard notebook computer in one position or like a clipboard in the second position. In fact, this "clipboard" aspect is where the tablet got its name. When used in the tablet configuration, the user can actually write directly on the screen using a special pen known as a stylus. Tablets use a special technology known as advanced handwriting recognition. Many also use speech recognition technology as well, which allows the user to record discussions, lectures, and so on, or to control the computer using voice commands.
- Personal digital assistants (PDAs) or handheld computers vary in size and purpose. Originally designed to provide a convenient resource for maintaining an organized calendar and list of business and personal associates, today's PDAs are capable of much more. Many PDAs now include personal productivity software and allow the user to play music, take photos, make phone calls, and access the Internet. Most PDAs use a stylus, a small sticklike device, to input information and access various features. However, it is not uncommon to find PDAs with small detachable keyboards for text and data entry. The line between PDAs and other mobile devices such as cell phones is becoming blurred, as each becomes more capable of doing the same types of tasks. Figure 1.2 identifies four different types of microcomputers.
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Objective 3 Describe Hardware Devices and Their Uses