Classic Computer Magazine Archive COMPUTE! ISSUE 135 / NOVEMBER 1991 / PAGE 52

How to Choose a VGA System
by Mark Minasi

Still using that old monochrome monitor? Suffering through video snowstorms whenever your CGA scrolls text? Or just tired of hearing your neighbors and co-workers brag about how great Windows looks on thei superduper whiz-bang VGA 800s?

In April of 1987, IBM introduced VGA with its PS/2 line. At that time, VGA was about the neatest video around for most PC users. In four short years, however, it has become the minimum ante for new computers. That's largely due to the greater emphasis placed on graphics today. Desktop publishing and Windows applications need graphics, and, of course, most games require at least EGA graphics to be attractive.

VGA has spawned a host of new problems, as vendors all seem to be offering their own variations of Super VGA. (And now there's XGA, but mortals like you and me won't be able to afford it--or the monitors it requires--for a while.) How do you know what to buy?

In this article, I'll show you how to choose the right VGA board and monitor for your system. I'll define terms and cost ranges, and keep you from spending a lot of money on a dead-end system that won't meet your needs.

VGA Board Basics

The VGA, or Video Graphics Array, video standard was preceded by several less-powerful standards: the Monochrome Display Adapter and its third-party cousin, the Hercules Graphics Controller; the Color Graphics Adapter (CGA), which offered low-resolution graphics (640 dots--pixels--across the screen, 200 pixels down); and the Enhanced Graphics Adapter (EGA). EGA offers good text and fairly nice graphics (640 x 350 resolution) but lacks 100-percent compatibility with CGA. It also has some design flaws that make writing software for it a bit of a chore.

VGA's entry in 1987 wasn't so much a revolution as a bug fix. VGA offers only slightly better resolution than EGA-- 640 x 480--but, more important, it fixes the CGA compatibility problem and the programming problem and the programming design flaws. And it adds much better color.

At the same time, IBM offered the 8514/A adapter, an even higher-resolution board (1024 x 768), but it's not that popular because it's fairly expensive, and its display is interlaced and thus hard to read.

There's not enough space here to explain interlacing in detail, but basically it's a trick to get a monitor to produce a higher resolution than it's capable of. A neat trick, but there's a side effect--the screen flickers. Work with an interlaced display for a while, and it'll drive you crazy and give you eyestrain headaches, so avoid interlaced video. By the way, the new XGA also has a 1024 x 768 interlaced resolution, so you want to avoid it unless you've got lots of aspirin.

No sooner had VGA come out than vendors began offering Super VGA boards. The first offerings were 800 x 600, a significant step up from 640 x 480. These boards were 800 x 600 interlaced, unfortunately. They were interlaced because the monitors available at the time--the original NEC Multisync, for example--couldn't handle noninterlaced 800 x 600. Today's monitors can display noninterlaced 800 x 600 and better, as we'll see.

How Much Memory?

Most VGA boards nowadays support Super VGA, even the inexpensive clones. You can pick up a no-name VGA board for about $80-$150, and in addition to standard VGA, it'll probably have some kind of 800 x 600 mode. The more expensive Super VGA boards ($200-$300) support 1024 x 768, either in interlaced or noninterlaced mode. More resolution means more dots on the screen, which means that the video board needs more memory to display those dots.

A video board's memory requirements are determined by two things: its resolution and the number of colors it can display. For instance, some VGAs can display 320 x 200 with 256 colors, but when in the higher 640 x 480 resolution, they can only display 16 colors. That has nothing to do with the constraints of the monitor or even of the VGA board except for the amount of memory on the board.

High Resolution

Standard VGA comes with 256K right on the board. Resolutions like 1024 x 768 with 256 colors obviously require more memory--that's why you see ads for VGA cards with an option for either 256K, 512K, or 1024K on the board. If all you're doing is regular old VGA, you only need 256K--there's no point in spending the extra money for 512K or 1024K. (I hear you asking, what resolution do I need? Hang on, I'm getting there.) Following is the amount of memory that a video board needs for the most common resolution and color combinations:

Horizontal Resolution x Vertical Resolution with Colors--Memory 640 x 480 with 16 colors--256K 640 x 480 with 256 colors--512K 800 x 600 with 16 colors--256K 800 x 600 with 256 colors--512K 1024 x 768 with 16 colors--512K 1024 x 768 with 256 colors--1024K

Should You Buy Super VGA?

Look in magazine ads, and you'll see that most VGA boards offer some kind of Super VGA mode. In many cases, you get a Super VGA mode free. Sounds like a good deal? It may be, but look closely; there are three catches.

* To use the Super VGA mode, you may have to spend twice as much money for a monitor that can display Super VGA than you would if you just bought standard VGA.

* Your application software may not support the Super VGA mode, and you have no guarantee that the video board vendor will be around in the next few years to supply you with drivers for the software. In a few years, your board's Super VGA mode may be a while elephant.

* Having all those extra pixels on the screen means that the processor must manage them all. Higher resolutions are generally slower.

Suppose you buy a no-name VGA card for about $90. Then you leaf through the documentation that came with the board and notice that it has a Super VGA 800 x 600, 16-color mode. The problem is, a standard VGA monitor (which costs $250-$350) won't display the 800 x 600 mode. You need a multifrequency monitor (which costs $450-$1,000) to display 800 x 600. (The section on monitors is coming up.) So the free Super VGA mode will cost you $200 more for a monitor to see the high resolution.

The second problem arises when you try to do anything with the Super VGA mode. You need a driver program for each of your applications to exploit Super VGA--a driver for 1-2-3, one for WordPerfect, and so on. How do you know that the VGA vendor will be around to continue to support his board? On the other hand, this won't be a problem if you buy your boards from a big-name vendor like Paradise, Orchid, Headlands Technology, Sigma, or ATI--they'll probably all be around for years to come.

The software compatibility problem may be reduced soon, however. A group of VGA vendors called the Video Electronics Standards Association, or VESA, has developed a set of standards for 640 x 480 with 256 colors, 800 x 600 with either 16 or 256 colors, and 1024 x 768 with either 16 or 256 colors.

If enough Super VGA board makers adopt the standard, then software vendors will begin supporting it. Prices on 800 x 600 monitors will soon drop, and 800 x 600 will be a good buy. Until then, consider carefully whether or not you really want Super VGA. Are you willing to put up with the annoyance of loading third-party drivers into Lotus? The documentation that comes with some of these boards is atrocious. And do you mind spending almost twice as much for a higher-resolution monitor, when standard VGA may be fine for your purposes?

Going to 1024 x 768 sounds nice, but there is one consideration that you never hear vendors talking about. The extra overhead that high resolution entails. You see, the video boards that we use in the PC world are almost all dumb--the CPU does all the work. For instance, if a program wants to put a picture of a circle on the screen, it must compute the location of all the dots on the screen and activate the corresponding pixels, one by one.

More advanced systems use an object-oriented approach, whereby the CPU just issues a command to the (intelligent) video board. For example, video board, draw a circle, place it here, and color it blue. That way, specialized hardware (called a graphics coprocessor) can be developed to speed up the graphical process.

The CPU could describe an entire screen with a few commands and go back to computing while the graphical hardware handled the tough work. These coprocessor boards are still very expensive--$1,000 and up. But they'd get cheaper if a lot of them were sold. I wish VESA had labored to develop a standard on graphics coprocessors rather than agreeing on how to burden the CPU further with more pixels to shove around.

How Many Bits?

Video boards were originally designed to cater to the lowest common denominator. In the PC world, this means XT-class machines. Since XTs aren't very fast, there wasn't any point in designing video boards to be fast. So older VGAs and VGA clones are fairly slow at putting text and graphics up on the screen.

One way to speed up video is to double up on the data transfer rate by buying a 16-bit video board. Older video boards transfer data 8 bits at a time, since that was the maximum rate XTs could handle. But any AT-class 286, 386SX, or 386 system can accommodate a 16-bit video board with no problem. So buy 16-bit video boards, rather than 8-bit boards.

In actuality, you'll find that most of the VGA boards available today are 16-bit boards. But there are still a few 8-bit boards out there, so take a minute to be sure that you're buying a 16-bit board.

There is one more feature yoy'll see on a few boards: VRAM, Video RAM. It's a special kind of memory chip that is not only high speed but also dual ported. What this means is that the video circuitry can read the memory at the very same time that the program is writing to it. That means snappier screens. It's a nice feature, but it's awfully expensive at the moment. Pass it up unless you need the very best.

Refreshing Monitors

A monitor provides the illusion of a clear, flicker-free display by painting 60 full-screen images on the CRT per second. If there were fewer images painted on the screen per second, you'd see a flashing or flickering effect, particularly on horizontal lines. The number of screens displayed per second is called the refresh rate or the vertical scan frequency. It's measured in hertz, abbreviated Hz. For example, 60 screens per second is a 60-Hz refresh rate. CGA, EGA, and VGA use a 60-Hz refresh rate.

Some vendors offer Super VGA boards that include 70- or 72-Hz modes, boards that refresh the screen 70 or 72 times per second, leading to a more solid screen. It may not sound exciting, but when you sit down in front of one of these VGAs, you'll know there's something different. Even if standard VGA doesn't seem flickery to you now. It will after you use a 70-Hz VGA for a while.

The downside of 70- or 72-Hz VGA boards is that they won't work with a plain-vanilla VGA monitor. You need a more expensive multifrequency monitor--the same kind you'd use for Super VGA. So if you've decided to go Super VGA, you might as well spend a little more and buy a board with 70- or 72-Hz VGA output, since you're buying the more expensive monitor anyway.

Monitor Mumbo Jumbo

A monitor works by directing a beam of electrons against the inside of its screen. Phosphors on the inside of the screen become excited and glow. Causing phosphors to glow or not to glow defines images on the screen. From a computer's point of view, a video display is just an array of pixels.

Resolution refers to the number of dots that can be put on the screen. The electron beam sweeps across the tube, painting lines of dots. CGA uses 200 lines top to bottom, EGA 350, and VGA 480. Since it uses higher resolutions, Super VGA does even more.

Consider the number of horizontal lines that a monitor must draw per second. In basic VGA, each screen has 480 lines, and there are 60 screens per second. 480 times 60 is 28,800 lines per second. That's called the horizontal scan frequency, as it's the number of times that the beam sweeps horizontally per second. It, too, is measured in hertz or kilohertz (kHz)--thousands of hertz.

Actually, VGA has a somewhat higher horizontal scan rate than 28,800 Hz (28.8 kHz), since the monitor has extra lines that you can't see (they're called overscan). How many extra lines a monitor has varies from video mode to video mode. A CGA monitor has a horizontal scan frequency of 15,750 Hz, or 15.8 kHz. EGA uses 21.8 kHz, and VGA 31.5 kHz. So the horizontal scan frequency your monitor needs to serve your board is determined in part by two important factors: the number of horizontal lines on the screen and the screen's refresh rate.

Dot Pitch

Monitor ads tout .28-mm dot pitch. What are they talking about?

We've seen that more resolution means more dots (pixels) on the screen. The width of the dots that the monitor can display is the monitor's dot pitch, and it's measured in millimeters (mm). The smaller the dots, the higher the horizontal resolution that a monitor can show in a crisp and readable manner. A larger monitor can have a larger dot pitch without sacrificing resolution, since its screen is larger.

In reality, you'll see four dot pitches for VGA monitors: .34, .31, .28, and .26 mm. Avoid .34 on 12-inch VGA monitors, but you may find it quite acceptable on 14-inch monitors--go take a look at one before you buy it. And .34 on a 14-inch monitor or .31 on a 12-inch monitor is fine for VGA only, but buy .28 if you plan to use a Super VGA in 800 x 600 resolution and .26 for a Super VGA using 1024 x 768 resolution.

Multifrequency Monitors

The last important monitor feature I want to mention is multisyncing, the ability to handle multiple resolutions automatically. Recall that the horizontal frequency you need to display an image is determined by the refresh rate (the vertical frequency) and the horizontal resolution.

Until 1986, monitors were fixed-frequency in both horizontal and vertical directions. When you bought a CGA monitor, it could only do one set of frequencies: 15.75 kHz horizontal, 60 Hz vertical. The EGA monitor had to be able to do double duty, as it could be attached to either CGA or EGA boards, and so had two sets of fixed frequencies: 15.75 kHz/60 Hz for CGA boards and 21.8 kHz/60 Hz for EGA boards.

Standard VGA knows three sets of frequencies: one for CGA modes, one for EGA modes, and 31.5 kHz/60 Hz for its native standard VGA mode. So a plain-vanilla VGA monitor is a fixed-frequency monitor that only supports CGA, EGA, and VGA--no high-resolution Super VGA modes.

In 1986, NEC changed that with its Multisync monitor. The Multisync could detect and synchronize with any horizontal frequency from 15 to 31.5 kHz and any vertical frequency from 50 to 70 Hz. That meant that a single monitor could work on any kind of video board available at the time. More important, when IBM introduced VGA in 1987, the Multisync was ready--it could handle VGA's 31.5-kHz horizontal frequency with no problem.

Now, most video vendors offer their own Multisync-like monitors. They're generically called variable frequency monitors (VFMs). NEC doesn't sell the original Multisync anymore, but it has Multisync models from the 3D (31.5-38 kHz horizontal, 50-80 Hz vertical; about $620 discounted) to the 5D (30-66 kHz horizontal, 50-90 Hz vertical; $3,700).

The competition's not asleep, however. The most reasonably priced high-resolution VFM is from Sony. The Sony Multiscan HG CPD-1304 (just call it the Sony 1304, and people will know what you're talking about) is a great deal--.26-mm dot pitch; 28-50 kHz horizontal, 50-87 Hz vertical; available discounted for $700. It'll display sharp non-interlaced 1024 x 768 screens, as well as 800 x 600 at a rock-solid 72-Hz refresh rate. For high-end Super VGA, the Sony 1304 just can't be beat.

Buying a VGA Board and Monitor

Whew! That's a lot of information. What's it all boil down to?

First, decide if you'll need standard VGA or Super VGA. In either case, buy a 16-bit board.

If you can be happy with standard VGA, then it's easy. Get a fixed-frequency VGA monitor, like the Gold Star or Samtron VGa. They can be found for about $250 to $350. For the VGA board itself, get a no-name VGA board with 256K of memory and a 16-bit bus interface. Don't waste money on more memory on VGA--it won't do a single thing for you. The board should run around $80-$100 from mail order and discount houses.

If you'd like to use Super VGA or 70- or 72-Hz VGA, you'll need to choose a VFM monitor.

Buy the Super VGA board from a big name--Paradise, ATI, Headlands Technology, Orchid, or Sigma. That way, you'll be able to get drivers for Windows version 7, AutoCAD version 22, 1-2-3 version 16, or whatever appears in years to come.

Among the five, the ATI boards are fast, flexible, and a bit cheaper than the others. Unfortunately, that lower price has inevitably led to poor support: ATI's support lines are constantly busy, they're often late in delivering drivers, and the drivers often leave something to be desired. (For example, the ATI VGA Wonder can display 1024 x 768 resolution, but the driver retains the low-resolution VGA fonts. The result is unreadably tiny letters. You'll get a headache after looking at the screen for more than a minute.) If you have a question for ATI, fax it in. You can usually get a one-day turnaround on questions faxed to tech support.

Paradise (Western Digital) and Headlands are a bit more expensive, but they're always right out in front with special drivers to allow their boards to strut their stuff. Orchid and Sigma are somewhere in the middle. Any of those five vendors' Super VGA boards are good buys--and don't forget to get enough memory to support the resolution that you intend to use.

And if you're going to get a Super VGA board, spend a couple of bucks more and get one with the 70- or 72-Hz refresh rate option. Your eyes will thank you.

More and more Super VGA boards support both 800 x 600 and 1024 x 768 resolutions. You may have to add some memory to the board in order to support the full 1024 x 768 resolution, however. A 512K Super VGA board from one of these vendors will run about $200-$300 discounted.

Super VGA Monitors

For a Super VGA board, you've got to choose a Super VGA monitor. Note that it will be a VFM. There are very few fixed-frequency Super VGA monitors, although the VESA standard may create a market for them. There are basically three levels of VFMs under $1,000.

The first group can synchronize up to 35.5 kHz horizontal. They're cheapest, and you shouldn't buy them. They can't do 70-Hz VGA, and the only way they can accommodate 800 x 600 is in an interlaced 56-kHz mode. This group is fading out, so they may be quite cheap, but save yourself some eyestrain and resist the temptation.

The remaining two groups are the 800 x 600 and 1024 x 768 camps. The 800 x 600s are represented by the NEC 3D ($620 discounted) or the Seiko 1440 ($480 discounted) that can handle horizontal syncs up to 38 or 40 kHz. (They also do vertical syncs up to 90 Hz). They'll display 70- or 72-Hz VGA and noninterlaced 800 x 600. They may even do interlaced 1024 x 768, but your eyes will fall out from eyestrain if you use that mode. If you're in doubt about whether or not a given monitor will work with your Super VGA board, contact the board's manufacturer for specific compatibility information.

The more expensive 1024 x 768 noninterlaced monitors are VFMs that can synchronize up to 50 kHz or more horizontal and 50 to 87 Hz or higher vertical. (87 Hz is a magic number because it's the frequency that 8514 would use if it were noninterlaced, and a few video board vendors offer a non-interlaced 8514.) If you need this resolution, buy the Sony CDP-1304 or something similar. But it won't come cheaply. Expect to pay $700 or more for the Sony and $250 or more for a Super VGA board with one megabyte of RAM on it.

Again, note that the big cost at high resolutions is the cost of the monitor, not the board. That's why XGA will be expensive for at least a few years. Unlike hard drives and motherboards, monitors aren't new--CRTs have been around for a while, so prices for 1024 x 768 monitors won't do the familiar nosedive that we've seen from memory, motherboards, drives, and the like. Prices will come down, but not tremendously. A 1024 x 768 monitor will probably cost around $500 in 1993.

VGA Bottom Line

To summarize, your choices are the following:

* Standard VGA--board costs around $100, monitor about $300.

* Super VGA (800 x 600)--board costs around $200, monitor about $500.

* 8514/A Super VGA (1024 x 768)--board costs around $250 (it has extra memory), monitor about $700.

So the packages for standard VGA, Super VGA, and high-resolution 8514 cost roughly $400, $700, or $950. Take your pick, and happy viewing!