Desktop Computer

The original IBM PC is the prototype for all desktop computers. The main box, the console, sits flat and square on the desktop. The monitor perches on top of the console, and the keyboard sits in front. Despite this historical tradition, few of today’s PCs resemble the IBM desktop original. The most popular computer configuration now is the minitower model, which is like a desktop model turned on its side . The minitower is more versatile than the old desktop style; you can set the console right next to the keyboard and monitor, or you can set the minitower on the floor and out of view.

A desktop computer typically includes one keyboard port, one mouse port, two USB ports, one parallel port, and two serial ports. The computer in the ad in Figure BG-1 has seven bays, two USB ports and one of which is a parallel port.

If you choose to buy a desktop, how much space is available for the computer? Towers can fit under a desk on the floor.

The quality of the computer display depends on the features of the video display adapter and the capability of the monitor. Monitors are rated by their resolution capability as well as the size of the display screen.

A typical desktop monitor can be 15", 17", 19", 21" or 27." the ad has a 17" screen with a viewable image size of 13.8". It also has a maximum resolution of 1280 x 1024.

A computer display system consists of a monitor and a graphics card, also called a video display adapter or video card. A graphics card is an expansion card that controls the signals that the computer sends to the monitor. Most computers include a graphics card, even if a monitor is not included. Graphics card specifications include the manufacturer, model, slot type, accelerator technology, and video memory capacity.

A hard disk drive (hard drive) is standard equipment on virtually every PC. Factors that influence hard drive performance and price include storage capacity, access time, and controller type. Capacity is measured in gigabytes (GB). When you compare computer systems, the hard drive capacity should be a significant factor in your analysis. Most of today’s computers are shipped with at least 80 GB of hard disk capacity.

Many multimedia, game, educational, and reference applications are available only on CD-ROM or DVD disks. A CD-ROM or DVD drive gives your computer the capability to access these applications. Today, every microcomputer comes configured with a CD-ROM drive. DVD-ROM drives are typically included with more expensive computer systems. DVD-ROM drives read CD-ROM, CD-R, CD-RW, DVD-ROM, and DVD movie formats. A CD-ROM drive cannot read DVD-ROM or DVD movie formats. The data transfer rate of the CD-ROM drive might be listed as 40X variable. This listing means that the data transfer rate of the CD-ROM varies between a minimum transfer rate of 2,500 KBps (17X) and a maximum speed of 6,0000 KBps (40X). Alternative terminology for 40X variable is 17–40X and 40X max. The computer in the ad has a 40x variable speed CD-ROM.

The microprocessor is the core component in a computer. Computer ads typically indicate the type of microprocessor, the company that manufactured the microprocessor, and the microprocessor’s speed. Intel and AMD are currently the two major PC microprocessor manufacturers. Computers that contain Intel processors command higher prices than computers that contain other manufacturers’ processors. • AMD produces “work-alike” processors for PC-compatible processors. AMD processors offer manufacturers and customers an alternative to processors produced by Intel. AMD processors are generally less expensive than their Intel counterparts, but have many of the same features and capabilities of Intel processors. • Intel also produces a “budget” processor called Celeron, which has a slightly less sophisticated architecture than Pentium models. • AMD produces K6 and Athlon processors that compete directly with Intel’s Pentium and Celeron processors. From a user’s perspective, it is virtually impossible to find any operational differences between computers that use AMD processors and those with Intel processors.

When purchasing a processor, two components to consider are speed and cache capacity.

• Speed: Processor speed is a measure of clock rate, which is an indication of the number of instructions that can be processed per second. A computer with a 2 GHz processor would be faster than a computer with a 2 GHz processor if all other specifications for the two computers being compared were equal. Manufacturers charge a premium price for speed. For certain applications, such as 3-D games and desktop publishing, the fastest processor can be very desirable. Applications such as word processing and e-mail don’t seem to benefit as much from accelerated clock speeds.

• Cache capacity: RAM cache is special high-speed circuitry that holds data just before the processor needs it. In theory, having a large cache area increases processing speed. Cache capacity is tied to the processor model. For example, a Celeron processor typically has 128 KB cache, whereas a Pentium IV typically has a 512 KB cache. Cache contributes to the speed of the chip and is often referred to in computer ads. The cache chip connects to the main processor by a dedicated high-speed bus and is often housed in the same chip carrier as the processor. With today’s computer architecture, cache is not configurable.

• Level 1 cache (L1 cache) is built into the processor chip.

• Level 2 cache (L2 cache) is memory circuitry housed off the processor on a separate chip. Level 2 cache is much faster than RAM and almost as fast as cache built into the processor chip.

choose a "performance" processor rather than a budget processor.

RAM—requirements and cost: The amount of RAM a computer needs depends on the operating system and application software you plan to use. Your computer should have at least 512 MB of RAM, but additional memory modules can be added. Most computers come with at least 1 GB. Consumer advocates recommend that you get as much RAM as you can afford with your initial purchase.

Read computer hardware selection guide.