Before You BuyHardware Basics

Excerpted from Buying a Computer For Dummies, 2006 Edition*

Nothing introduces you to the time-honored computer theme of using three-letter acronyms (TLAs) better than computer graphics. For the hardware, fortunately, only two TLAs are worth knowing: CRT and LCD. These terms describe the two basic types of monitors now available.

CRT stands for cathode ray tube, which is the glass part of any traditional TV set or computer monitor, as illustrated in Figure 1. The advantage of CRT monitors is that they're inexpensive. The disadvantages are that they take up a great deal of desk space and are bulkier, heavier, and not as energy efficient as LCD monitors. Still, that "cheap" aspect weighs in favor with most computer buyers, so they often go with the traditional CRT monitor.

LCD stands for liquid crystal display, which is the new flat-screen monitor that's all the rage, as shown in Figure 2. These monitors are essentially the same types that appear on laptop computers, though they're designed for use with a desktop model. LCD monitors are thin, lightweight, and energy saving. Plus, they look very, very cool on your desk. The drawback? They cost more than comparable CRT monitors.

The following list highlights the features of CRTs and LCDs:

• Both CRT and LCD monitors connect to the same type of graphics adapter plug on the back of your PC.
• Some high-end LCD monitors sport their own, unique digital graphics adapter. For example, the Apple LCD monitors connect to the digital port on the G5 Macintosh line of computers.
• Some LCD monitors rotate 90 degrees, which allows you to view them in portrait and landscape modes.
• The best way to judge an LCD monitor is to view only text on the screen. Don't be fooled at the store by fancy graphics displays, which always look stunning. The true test is viewing text, not graphics.
• Be sure to check the LCD in a variety of lighting situations. Some monitors cannot be seen in very bright lights. Some monitors cannot be seen from far right or left angles.
• Unlike LCD monitors, most CRTs let you display graphics in a variety of resolutions and color settings. LCDs, on the other hand, typically use only a few modes to display things.
• CRT monitors emit more radiation than their LCD counterparts, although it's not enough to create a 1950s-era horror movie creature.
• Be sure to compare LCD versus CRT at the larger aspect ratios. Some larger LCDs tend to lose their color saturation, whereas larger CRTs don't.

• Don't confuse LCD with flat-screen monitors. All LCDs are flat screen. But a few CRTs have flat picture tubes and are advertised as being flat screen. It's not the same as having an LCD monitor, though the flat-screen CRTs display a nicer image than traditional curved-screen models.

Don't get an LCD if you plan to play fast-action computer games! Generally speaking, LCDs are too slow to update for real-time game action. True gamers use only CRT monitors.

• Another area where CRT monitors are better than LCDs is in high-end graphics. A CRT monitor can better render color images than an LCD, which has a more limited range of color reproduction.

Missing LCD pixels

Unlike a CRT monitor, an LCD monitor creates its image by having millions of individual pixels on the screen – like tiny red, green, and blue lights. Although this technique produces a much sharper, less-flickering image than a CRT, the odds are really good that some pixels may arrive "dead" on your monitor.

A dead pixel on an LCD screen can be obvious or obscure. They show up well only when the screen is blank; one pixel is green, and the other is red. You normally don't notice them. Some of the better monitors don't have any dead pixels.

How many dead pixels are okay? It depends on the monitor manufacturer's warranty. If you get an LCD monitor, first check the warranty to see how many dead pixels are considered okay. Then run a monitor diagnostics program to see whether the monitor has, in fact, any dead pixels. (The diagnostics program comes with the monitor.)

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