Classic Computer Magazine Archive START VOL. 5 NO. 5 / JANUARY 1991



Your One-Stop Resolution Shop

Hardware Editor

Talon Technologies' Omniswitch
lets you conned a multisynch
monitor to your ST.

There's a joke among computer pundits that goes like this: How many programmers does it take to screw in a light bulb? Answer: None, that's a hardware problem.

All kidding aside, in the coming months, in this column we will discuss the world of Atari hardware. We'll cover computers, printers, disk drives, modems - any piece of hardware that has anything to do with Atari computers, including some that normally do not.

Monitoring Your World
One of the most important pieces of equipment you have in your ST system is your monitor. This is your window on the world the ST presents to you.

Atari offers seperate color and monochrome monitors for your ST. Until now, you had to use these -there were no low-cost third-party monitors you could use without internal hardware modifications to your computer. And if you wanted all three ST resolutions, you had to have two monitors.

But while the Atari monitors do a fine job, there are several drawbacks (besides having to have space for two monitors) to the fact that they've been the only game in town. Most notably, they're quite small. The picture area of a standard SM124 is just under 12 inches (measured diagonally). However, there's a substantial black border around the screen, so the working area is more like 9.75 inches (measured diagonally). There's no easy way to expand the picture area (though we'll look at some not-so-easy ways in the future), so you're basically stuck with the small screen.

Another drawback is that Atari monitors can be quite difficult to find. For reasons that only Atari knows, the SM124 has been in short supply since the beginning of 1990.

The Alternative
Most present and potential ST owners may not be aware of multisynch monitors. A multisynch monitor can produce both color and monochrome modes in one monitor, alleviating the need to own two different monitors. They're more expensive than the Atari monitors, but are comparable in price to two Atari monitors combined. Plus, they're available in all sizes, up to 25 inches diagonally. Let's take a look at what a multisynch monitor is and how you'd go about connecting one to an ST.

Some Background
The multisynch monitor originated in the IBM world. When the PC was first developed, it had only monochrome text. This was followed shortly by a color mode called CGA, capable of producing four colors on a 320 x 200 pixel screen. Before long, owners of PCs outgrew CGA, and a new standard developed, called EGA. This mode could show 16 colors in 320 x 200 pixels, or four colors in 640 x 350 pixels. A while later, vet another standard emerged, called VGA, with even more impressive characteristics -the ability to display 256 colors in 320 x 200 pixels, or 16 colors in 640 x 480 pixels.

As you can imagine, each of the color modes required different things from a color monitor. The primary difference is that each mode required more information to be displayed on the screen - more colors, more lines of resolution, more pixels on each line. With each increase in graphic capability, a better, faster monitor was needed.

Until now, there were no
low-cost third-party monitors
you could use with the ST.

The speed of a monitor is measured by its scan rate, and with each increase in graphics, the scan rate of the monitor had to he higher to remain in synch with the graphic signal coming from the computer. The problem was that you never knew what kind of a program von might run - some were CGA, some EGA, some VGA. The new graphics cards in the PCs could produce signals consistent with any of the modes, depending on what the software told it. But short of owning three different monitors, what could you do? The answer was a multisynch monitor - One that could sense the scan rate demanded by the computer and automatically synchronize to that rate. Before long, a whole host of well-known companies brought multisynch monitors to the market.

Scan rates are measured in cycles per second, also referred to as hertz or Hz. The horizontal scan rate is quite a bit higher than the vertical scan rate, and is thus measured in hundreds of cycles per second (KHz). The normal range of scan rates that a mtiltisynch monitor can synchronize to is 15KHz to 36KHz horizontally and 45Hz to 90Hz vertically. This range lets the monitor synchronize to CGA, EGA and VGA. There are monitors that have higher scan rates so that they can synch to extended VGA, but these cost quite a bit more and are unnecessary for most applications.

What It All Means
Now that we have all that out of the way, let's look at what it means to the Atari owner. The ST has two different scan rates, which is why it requires two monitors. For color modes (low and medium resolution), the scan rates are 15.8KHz horizontally and 60.3Hz vertically. In monochrome mode, the rates are 31KHz horizontally and 70Hz vertically. Thus, a standard multisynch monitor can automatically synchronize and produce both color and monochrome modes from a single monitor.

How many programmers
does it take to screw
in a light bulb?

Making The Connection
So, how do you connect a multisynch monitor to your ST? It's not too difficult to build a cable, but the easiest way is the purchase Omniswitch from Talon Technologies. This small box has a port on the hack to which you attach a standard ST monitor cable to its corresponding port on the ST. There are two multisynch monitor ports (because there are two different types of cable that can be used for a multisynch monitor) to which you attach the cable that comes with your multisynch monitor. Plug in the end of the multisynch cable to the monitor itself, and you now have a monitor capable of displaying all three resolutions.

When used with an ST, muhtisynch monitors have a significant border, so that a 14-inch monitor produces an active picture area hardly bigger than that of a standard Atari monitor. Some monitors have controls that adjust the picture size, which can help to eliminate the useless border. However, increasing the picture size in color mode means you'll have readjust it when you switch to monochrome mode.

Also, you may see monitors advertised (for a considerably lower price) as "multiscan." These are not the same as multisynch. A multiscan monitor can automatically synchronize to a certain fixed set of scan rates - those corresponding to CGA, EGA and VGA on the IBM PC. These rates will do the ST owner no good.

Produts Mentioned
Omniswitch, $89.95. Talon Technologies, 243 N. Highway 101, Suite 11, Solana Beach, CA 92075 (619)792-6511