FROM time to time, I like to let the readers take over, and the last few weeks have produced some particularly good questions. So here we go.
Q: Please address in your column why monitors cost so much. For example, a 20-inch monitor costs far more than a 32-inch TV set. How come?
A: While monitors and TV sets look alike and both display images on cathode ray tubes, the resemblance ends there. Anyone who remembers the days when home computers hooked up to TV sets can tell you that televisions weren't designed to display high-resolution text and graphics. In fact, they were awful.
Compared to a television, a computer monitor is a precision instrument. It has much finer resolution because it's designed to be viewed from a distance of one or two feet instead of from across the room.
Monitors also are engineered to work at different resolutions -- for example, with Microsoft Windows, you can set your video display to 640 by 480 pixels, 800 by 600 pixels or 1,024 by 768 pixels. TV sets only work at one resolution.
Your monitor has to hold a precise image from edge to edge, and it has to be so sharp that you can easily make out fine lines or characters that might be only one or two pixels wide. You don't make those demands on a TV set.
Monitors also have much higher refresh rates than TVs. A television refreshes the screen 30 times a second, and it "interlaces" the image, which means it lights up only half the lines on the screen with each pass.
This is acceptable for moving images viewed from afar but not for close-up work. Today's monitors refresh the screen anywhere from 60 to 85 times per second, and they light up each row of pixels with each pass.
Finally, look at the controls on a good monitor, and you'll find all kinds of gadgets you won't find on a TV set. You can expand or contract the image, move it in four directions and correct pin-cushioning and barrel distortion -- in addition to setting brightness and contrast.
The electronic circuitry required to do all these things is very expensive, and it gets even more expensive in larger monitors -- 17 inches and up. Although large monitors are becoming more affordable (good 17-inch models are available for $500 to $700), their numbers still aren't large enough to generate the economies of production that TVs do. So you pay more.
Q: I'm thinking of buying one of the new 56K modems. But I'm worried that it won't work if I call computers using older modems. Is this something I should be concerned about?
A: There are a lot of things that make a 56K modem an iffy proposition right now, but backward compatibility isn't one of them.
The advertised speed of a modem is its maximum data transfer rate -- they'll all communicate at lower speeds. In fact, most modems automatically adjust to the modem at the other end of the line.
The squealing and chirping you hear when you make a connection is the sound of the two modems negotiating a mutually agreeable speed and transfer protocol.
The latest generation of modems theoretically can pump 56 kilobits of information per second (enough to transfer this column in a second or less). But that's theoretical.
The problem is that the modem industry is engaged in a standards war around competing 56K transmission schemes called x2 and K56 Flex. The two types of modems aren't compatible with each other for high-speed work -- although they can communicate at lower speeds.
Worse yet, neither is likely to be completely compatible with the standard that will be adopted early next year by the International Telegraphic Union.
While most manufacturers promise that they'll upgrade the 56K modems that customers buy today, think twice before you replace a good 28.8 or 33.6 kbps modem right now.
If you wait a while, you'll get the real thing.
By the way, even when the 56K standard is agreed upon, you'll only be able to achieve speeds above 33.6 kbps if you're dialing an Internet provider who has a high-speed connection to the Net.
And that's only if you have an absolutely perfect phone connection.
I've rarely been able to get a connection faster than 24 kbps with my current modem.
Comments? Questions? Suggestions? You can contact Mike Himowitz by sending e-mail to mike.himowitaltsun.com.
Pub Date: 9/21/97