A computer monitor may be the last peripheral on your wish list. After all, an extra color or even black-and-white TV set works fine with most home computers. But lower monitor prices, new accessories, and combination TV/ monitors are quickly changing the picture for the better.

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Until about a year ago, most computer owners didn't have to spend too much time deliberating over which computer display to buy. Color monitors cost more than brandnew color TV sets, so most people didn't buy a special display for their computers-they just used TV sets. Others used spare black-and-white sets, even for computers with color graphics.
    But recently the options have widened. Thanks partly to Commodore's unexpected success with the 1701/1702 color monitors, manufacturers have spotted a niche in the market that was not being exploited, and now they're scrambling to fill it. In addition, TV manufacturers are finally realizing that TVs are being used for a lot more than just watching TV - people are plugging in home computers, videogame machines, videocassette recorders, stereo sound systems, and videodisc players.
    The result is a wider variety of affordable color and monochrome monitors compatible with nearly all home computers, plus a new generation of combination TV/monitors equipped with an array of video and audio input/output jacks. There is even a combination TV/ composite color/RGB color/ monochrome monitor that sells for not much more than an old-fashioned color TV. And new low-priced accessories let you turn existing computer monitors into TV/monitors.
    Since the display device is the most-used peripheral in a computer system (you're staring at the screen for up to hours on end), it's time to take a fresh look at what's happening in computer video.

Unlike many peripherals, a monitor will probably be compatible with a different computer if you ever upgrade your system. So it makes sense to take special care when selecting one. It's also important to understand all the technical terms and specifications (see the accompanying article, "RGB Versus Composite Video").
    Resolution refers to how sharply the screen can display an image. The greater the resolution, the better. For several technical reasons, ordinary TV sets have trouble displaying computer text. That's why all home computers designed to work with TVs limit the width of their displays to no more than 40 characters. An 80column display-standard on business computers-would be too fuzzy to read comfortably on the average TV.
    You can quickly convert most home computers for 80-column text by plugging in a video adapter board or by running a special program. But to read the screen without suffering headaches, usually you must buy a monochrome (noncolor) monitor. Monochrome monitor, are available with black-and-white, green, and amber displays (some studies suggest tha green and amber displays are easier on your eyes). Why must you buy a monochrome monitor? Because even the most common type of color monitor-called a composite color monitor-has problems displaing 80 columns of text. People '' who spend lots of time staring  at the screen, particularly writers and programmers, need the sharpest resolution possible to avoid eye fatigue.
    Until recently, the only other alternative was to buy a much more expensive type of color monitor, an RGB (red-green-blue) monitor. But few home computers have RGB - compatible outputs, though sometimes one can be added at extra cost.
    Fortunately, improved technology has drastically cut the price of RGB monitors and has made it possible for some composite color monitors to display sharp 80-column text as well as graphics. For instance, Teknika Electronics makes a 13-inch color monitor, the MJ-10, that has both composite and separated video, just like a Commodore 1701/1702. The separated video mode-which separates certain components in the video signal-can produce an acceptably sharp 80-column display on computers with separated video outputs. Although the only computers with such outputs are the Commodore 64, Plus/4, Commodore 16, and Atari 800, the Teknika MJ-10 also works in regular composite mode with the IBM PC and PCjr, Apple, Atari XLs, and Commodore VIC-20. The suggested retail price is $299.
    Teknika's MJ-22 is also a 13-inch color monitor, but is switchable between composite video and RGB. Retailing at $439.95, it is several hundred dollars less than what RGB monitors used to cost and is compatible with the IBM PC and PCjr, Apple, Atari, Commodore, and Texas Instruments computers. Sakata Corporation, a Japanese electronics manufacturer, also makes a composite video/RGB monitor for under $500, the SC-150.

Other companies are marketing color monitors with multiple display modes, too. Perhaps the most versatile to date is the Sears Total Video System. At the push of a button, you can use its 13-inch screen as a composite color monitor, RGB color monitor, green-screen monochrome monitor, or as an ordinary TV set. It even has a button that shrinks the screen image slightly to tighten the dot patterns for sharper text in RGB mode. The RGB jacks are directly compatible with the IBM PCjr, and an adapter makes it work with the PC, too. The monitor is also compatible with virtually all other microcomputers. Its suggested retail price is $349 - about half as much as what comparable RGB-only monitors used to sell for.
    General Electric has two multifunction models. Like the Sears Total Video System, the 13-inch GE Computer Monitor/ TV has an input jack that allows a composite color video signal to bypass the TV's tuner circuits, resulting in a cleaner display. GE also offers a 12-inch black-and-white TV/monitor. (GE has no suggested retail prices; check your local dealer.)
    Manufacturers are beginning to equip their TVs with video and audio input jacks because they also make it easier to connect other video devices, such as videocassette recorders. Watch for the next generation of TVs to have a complete set of input/output jacks as a standard feature, just like stereo receivers. These jacks add relatively little to the manufacturing cost of a TV and help eliminate tangles of wires and switchboxes. They also make the TVs a good buy for families who don't use their computer often enough to justify the cost of a dedicated computer monitor.
    If you already have a computer monitor, and you live in a household where the arrival of the weekly TV viewing schedule is a springboard for major debates, new add-on tuners can convert your existing monitor into a combination TV/monitor, too. One example is the Cardco Monitor Tuner, which turns any composite color or monochrome monitor into a TV for $99.95. It has an audio output (which can be connected to a stereo system), a computer/TV switch, and a cable/antenna input. A slightly more expensive model has remote control.

Now you can watch TV while waiting for programs to load: Cardco's Monitor Tuner converts any composite computer monitor into a combination TV/monitor.

RGB Versus Composite Video Ottis Cowper, Technical Editor Color video is similar in principle to monochrome video, the original black-and-white television technology. In a monochrome monitor (or black-and-white TV), the image is produced by spraying the screen with a beam of electrons from a hot filament (called a gun) at the back of the picture tube. The screen has a special phosphorescent coating that glows wherever the electrons strike. By carefully aiming the gun to illuminate certain phosphor dots on the tube, detailed images can be painted on the screen. Thus, four separate signals are required to create a monochrome video display: one to control which dots are illuminated, one to control the intensity (brightness) of the display, and one each for synchronizing the vertical and horizontal targeting of the beam.     The challenge in making the leap from monochrome to multicolor was to devise a simple method of generating all the subtle hues the human eye can distinguish. It's possible to make phosphors that will glow a particular color; witness the black-and-white, green, and amber monochrome monitor screens now available. But a color screen would seem to require thousands of different phosphors for all the desired colors. Fortunately, the process isn't quite that complicated.     According to optical physics, all visible colors can be created by mixing just three primary colors in various proportions. For color video, the primary colors are red, green, and blue. Any other colors you see on a computer display or color TV are combinations of these three.     On a monochrome display, each of the tiny spots that make up a figure consists of a single glowing dot of phosphor. On a color display, three closely spaced phosphor dots are required for each point-one red, one green, and one blue. As a result, the smallest element of any feature on the color display will be at least three times larger than the smallest element on a monochrome screen. This is one reason why color displays tend to be less sharp-to have lower resolution-than monochrome displays.     A color display, then, requires six separate signals: one each for red, green, and blue dots (replacing the single signal required for monochrome dots), plus the intensity, horizontal, and vertical control and synchronization signals. The differences between composite video and RGB (red-green-blue) color displays have to do with how these signals are sent to and processed by the monitor.     Composite video is the most common system because the circuitry is quite similar to that for a color TV, so the components are readily available and relatively inexpensive. As the name composite video implies, these monitors receive and process a composite signal-one in which all the separate signal elements for the display are combined into a single signal. The monitor divides the composite signal from the computer into its various parts to target the electron gun and illuminate the proper colored phosphor dots.     In an RGB color monitor, each of the different phosphor colors is illuminated by a separate gun-hence the name RGB. Rather than sending the monitor a composite signal, the computer sends each signal separately, and separate circuits in the monitor target each of the three electron guns. The colors are mixed more precisely and appear much sharper. The disadvantage is that the more specialized circuitry costs more.     At present, there is also one intermediate step between composite video and RGB. The Commodore 64, Plus/4, Commodore 16, and Atari 800 computers have video outputs that can separate the color portions of the composite signal from the intensity portion. The two signals are referred to as chroma (short for chrominance, or color) and luma (for luminance, or brightness). The Commodore 1701/1702 color monitors can accept these separated signals in addition to standard composite video. The chroma/luma separation yields a picture that, while still less sharp than RGB, is a distinct improvement over standard composite displays.     The choice between composite and RGB displays may be quite simple. If you have a computer that is designed to provide only composite video output-as is the case with most home computers-then the higher quality of an RGB display is unavailable to you. We know of no adapters to break a composite signal into its RGB components. If, however, you have an IBM PC with a color/graphics adapter, an IBM PCjr, or perhaps an Apple or Atari 800 with an RGB adapter card, you can compare the two systems and decide if the superior quality of RGB is worth the higher cost.

    You can also use a videocassette recorder to convert a monitor into a TV. Just run a cable from the VCR's video output jack to the monitor's video input jack, and then use the VCR's own tuner.
    Another new accessory turns RGB color monitors into very sharp monochrome monitors. The GreenSwitch, from Future Products, changes the screen color to green-on-black. The switch has an IBM - compatible, nine-pin D-connector, installs easily with a screwdriver, and retails for $49.95.

Sakata Corporation caused a bit of a stir with a new monitor at last fall's COMDEX trade show in Las Vegas. Publicity Director Sandy Rodkin, of Rodkin & Associates, recalls seeing a cable TV crew pass by their display, stop, and stare. "Why is that picture better?" they asked.
    The monitor they were looking at was a new flat-screen model, the Sakata SFS-200. It has a color liquid crystal display (LCD) that is not only extremely sharp, but more portable than a conventional cathode ray tube (CRT). Small monochrome LCD screens already are common on portable lap computers such as the TRS-80 Model 100. Large color flat screens are still relatively expensive and slow (the SFS-200 costs almost $1,000), but manufacturers expect that to change over the next year or two.
    The quality of home computer displays has traditionally been limited by the most common type of display device, the living room TV. But as video technology improves, and prices drop, we can look forward to a new generation of home computers with the kind of highresolution graphics and sharp 80-column text found today only on the most expensive high-end computers.

For more information, write: Cardco, Inc. 300 S. Topeka Wichita, KS 67202 Future Products 3864 Scamman Ct. Fremont, CA 94538 General Electric Video Products Division Portsmouth, VA 23705 Sakata U.S.A. Corporation 651 Bonnie Ln. Elk Grove Village, IL 60007 Sears, Roebuck & Co. Sears Tower Chicago, IL 60684 Teknika Electronics Corporation 1633 Broadway New York, NY 10019