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The Quest for the Ultimate Display System

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        К                                                              К
        К                       The Quest for the                      К
        К                    Ultimate Display System                   К
        К                                                              К
        К                              by                              К
        К                         Steve Gibson                         К
        К                  GIBSON RESEARCH CORPORATION                 К
        К                                                              К
        К     Portions of this text originally appeared in Steve's     К
        К               InfoWorld Magazine TechTalk Column.            К
        К                                                              К
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        I remember those simple days not so long ago when a purchaser of
        a brand new IBM Personal Computer had only one choice to make
        when it came to choosing the display system for his computer.
        Blessedly, the only choice to be made back then was between
        either a monochrome display and adpater, the so-called MDA
        solution, or a color screen and adapter, and CGA route. Needless
        to say, things are not so simple or straightforward these days!
        There are so many choices and options open to a purchaser or
        upgrader of a PC that I'd be crazy to even ATTEMPT to offer any
        clarification or guidance.

        Okay, so call me crazy. It's time to choose the display
        subsystem for Steve's Dream Machine and I've got some real
        surprises in store for you this time! I've spent most of the
        past six weeks (when I haven't been reconfiguring my system
        between VM/386, Desqview, and Omniview) researching, probing,
        and digging for the best possible contemporary display solution
        for the least possible money.

        Surprisingly, my research has uncovered some truly startling
        facts which I'll be sharing through the next few weeks as we
        explore THE DISPLAY SYSTEM FOR STEVE'S DREAM MACHINE. We'll see
        things like why the new 16-bit display adapters are generally
        not worth a dime more than their older 8-bit predecessors, how
        few, if any, VGA adapters on the market are REALLY register
        level compatible, and what risk that represents in light of
        IBM's unknowable future plans. We'll see what extra display
        memory DOESN'T buy for you because many of the manufacturer's
        device drivers don't even use it, why the highest resolution
        modes can be much more trouble than they're worth, and what NOT
        to pay for a great high resolution display.

        Given the incredible variety of available choices (not at all
        like in the old days) it may surprise you to know that I have
        found ONE set of choices which delivers far more bang for the
        buck than any other! In order to give these conclusions a proper
        perspective, let's first step back for a moment to review the
        technological fundamentals and constraints which give our
        decision meaning. Then we'll see where we've been and where
        we're going.

        No matter what style of display screen and interface adapter is
        in use, several fundamentals always apply. In the first place,
        the image displayed by a CRT screen is not at all the static
        image which it appears to be. In fact, there's never really an
        image being displayed on the screen at all! If you were to
        photograph a computer display screen with a high speed camera
        you'd only see a single bright dot of light rather than an
        entire image.

        The illusion of a screen full of information is created with the
        aid of some incredible technology. The screen is actually
        painted by a single madly whizzing dot of light which traces
        successive horizontal lines across and down the face of the
        display tube. When I say "madly whizzing" I'm not exaggerating
        because a typical CRT screen paints horizontal scan lines on its
        face at the rate of 350,000 inches per second, which is 20,000
        miles per hour! This furious speed is required in order to fool
        our eyes into believing that the entire image is being
        continuously displayed when in fact it's mostly NOT being
        displayed!

        A typical display screen consists of about 450 of these
        horizontally scanned lines, each of which must be redrawn or
        "refreshed" at least every sixtieth of a second. This means
        scanning across 27,000 lines per second, every second. If this
        is not done our eye will perceive that the lines are not being
        continuously illuminated and the illusion we've tried so hard to
        achieve will fail.

        As the single dot of light traces its furious course it changes
        color thus tracing out the full screen image which is stored in
        the display adapter's DISPLAY REFRESH MEMORY. On a monochrome
        screen which is limited to displaying a single color, the dot of
        light varies in brightness only, whereas a color display system
        allows the dot's instantaneous color to be varied as well.

        So we're left with a number of important concepts: In order to
        eliminate the overall "refresh flicker" of a display screen, the
        entire screen must be redrawn or repainted approximately 60
        times each second. Since the scanning dot traces lines from left
        to right as it moves more slowly vertically from the top of the
        screen down, the downward motion is referred to as the screen's
        Vertical Refresh Frequency and the very rapid horizontal left to
        right scanning is referred to as the display's Horizontal
        Refresh Rate.


                     The Display System Adventure Continues


        So we've seen that the display screens of our computers rely
        entirely upon our eye's persistence of vision to assemble the
        illusion of an image on the screen. Each dot which composes the
        display must be redrawn, or refreshed, at least sixty times each
        second in order to appear continuously illuminated. Now we'll
        examine the evolution of our display screens, giving some
        perspective to where we've been and where we are today.

        The original Color Graphics Adapter (CGA) traces its ancestry
        directly from commercial television. Commercial TV refreshes its
        screen exactly 60 times per second with a horizontal scanning
        frequency of 15,750 cycles per second. The IBM CGA display
        utilizes this timing to support the images it generates. The
        total number of horizontal scanning lines traced onto the screen
        by a CGA system can be determined simply by calculating how many
        horizontal lines are scanned out during one vertical scan. Since
        the screen is scanned vertically 60 times per second, we divide
        15,750 by 60 to yield the horizontal line count of 262. Two
        hundred of these scan lines are used to display actual image
        data, with the balance used to illuminate the CGA screen's border
        region.

        As we all remember, the CGA was not known for producing highly
        legible text (for some it's not yet a memory). The prime
        determiner of text quality is the number of individual pixel
        dots which are available to display individual characters.
        Dividing 200 total image lines by 25 lines of text yields just 8
        scanning lines available per text line. Then since the CGA
        adapter was able to display 640 dots across a horizontal line,
        dividing this by 80 characters per line yields 8 pixel dots
        horizontally per character.

        So CGA technology yielded a budget of 8 by 8 pixels per
        character. Since it is necessary to separate characters by at
        least one blank pixel, and since characters are taller than they
        are wide, CGA characters were designed to fit within a rectangle
        of dots 5 wide by 7 dots high. If you have a few moments to
        spare some time with some graph paper, try designing an entire
        upper and lower case alphabet where each character fits within a
        5 by 7 pixel cell. It's not simple, and there is no really great
        solution.

        Driven by the concern that serious business computer users would
        be very unhappy with the appearance of CGA text, IBM decided to
        provide a better text display alternative. The Monochrome
        Display Adapter (MDA) was the result. In order to deliver more
        legible characters, more pixels are required both horizontally
        and vertically. Where the CGA fits 5 by 7 characters into 8 by 8
        "cells," the IBM monochrome display provides much higher
        resolution: 7 by 9 characters within a 9 by 14 space.

        Changing the character resolution from 5 by 7 to 7 by 9 results
        in a tremendous improvement in character legibility, and a 2-
        pixel horizontal inter-character spacing with a 5-pixel vertical
        spacing leaves the display's characters feeling quite uncrowded.

        The question is, where did IBM get all those extra scan-lines?
        25 lines of text with 14 scan-lines per line means a total of
        350 active scan lines compared to the CGA's 200! The scan-line
        count can be increased by increasing the horizontal scan
        frequency so that more lines are scanned per second, or by
        decreasing the overall vertical refresh rate thus allowing more
        time to scan the horizontal lines.

        IBM did both of these things to create the MDA standard. The MDA
        refreshes its screen at only 50 cycles per second with a
        horizontal scan rate of 18,432 hertz. Now, dividing 18,432 by 50
        yields about 368 scan lines. Since 350 of these are required for
        text display, the MDA is not able to display a border.

        But how can IBM refresh the MDA screen at only 50 cycles per
        second if we begin noticing a flicker as refresh frequencies
        fall below 60 cycles per second? IBM compensated for our lack of
        vision persistence by designing a highly persistent green
        phosphor into their monochrome display. Many people immediately
        noticed a "smeary" effect whenever the IBM monochrome display
        scrolled text. This smearing was created by the use of a long
        persistence phosphor which continued to glow long after the
        screen's electron beam stopped refreshing the region.

        If you've ever noticed an annoying continuous flicker from an
        inexpensive clone monochrome display, now you know why. Most
        clone monochrome displays use less expensive standard short or
        medium-length phosphors... which are inadequate for masking the
        very noticeable effects of the MDA's lower refresh rate. Also,
        since the flicker-perception phenomenon is extremely subjective,
        many people perceive flicker where others don't. I've
        learned that I don't see flicker where other people are being
        driven nuts by it.

        With an understanding of the interactions of horizontal and
        vertical scan rates and display resolution we're ready to
        explore the EGA, VGA and multisync technologies.


                         The role of Hercules Graphics,
                          and the evolution of the EGA


        We've seen how IBM designed their MDA monochrome display system
        to deliver extremely well-formed characters by increasing the
        display's horizontal scanning rate and decreasing the vertical
        refresh rate. Before continuing our discussion of EGA, VGA, and
        multisynchronous monitors, it's important to understand another
        quite well established and significant display standard,
        Hercules.

        Perhaps IBM simply overlooked the idea of monochrome graphics
        altogether, or underestimated the demand for the display of
        graphic information. More likely though, IBM felt that the word-
        processing market toward which they were targeting their
        monochrome display system had no need to display graphics. How
        could IBM, or anyone for that matter, have anticipated the
        phenomenal effect Lotus' 123 spreadsheet product would have upon
        the IBM compatible market?

        While columns of numbers are indeed informative, the ability to
        graphically display, correlate, and view the results of
        spreadsheet calculations is extremely useful. The folks at
        Hercules Computer quickly recognized this and designed a
        wonderful solution which, with the early support of Lotus, became
        a solid standard.

        Since the Hercules high resolution mode was designed to operate
        with an IBM or compatible monochrome monitor, at a horizontal
        sweep rate of 18,432 cycles per second and a refresh frequency
        of (only) 50 hertz, it could directly leverage the extremely
        high resolution which IBM had designed into their monochrome
        text system. The Hercules monochrome display resolution of 720
        by 350 pixels made the CGA's 640 by 200 look quite sad when
        compared side by side, and suddenly people could have both
        readable text and great looking graphics at the same time and
        from a single system.

        IBM's next move demonstrated that they'd been listening to their
        user's complaints about the low resolution of the CGA standard.
        They were also watching the guys at Hercules make money like
        crazy and were attempting to serve the always mixed blessing
        requirements of full backwards compatibility. The IBM Enhanced
        Graphics Display was IBM's second generation solution, and
        it rapidly became a new standard for the industry.

        By recognizing the CGA system's crying need for better text, IBM
        saw that it had to crank up the scan line count to something
        more like their monochrome display; however, since full-color
        long persistence phosphor monitors are barely affordable by
        small countries, IBM knew that it couldn't play the trick of
        getting the scan line count up by lowering the system's overall
        refresh rate below 60 cycles per second. The only alternative was
        to push the system's horizontal scanning frequency higher than
        the monochrome system's.

        This would mean that their new EGA display system would not be
        backwards compatible to the existing installed base of 200 scan
        line resolution CGA software. (The non-optimal solution crimes
        which are continually committed in the name of backwards
        compatibility is probably my single
        biggest pet peeve. It directly accounts for the unprogrammablity
        of the Intel microprocessor instruction set!) So, in order to
        achieve CGA compatibility from their new EGA system, IBM
        invented the "bi-synchronous" display system.

        By inverting the polarity of the EGA monitor's Vertical
        Synchronization signal, the EGA adapter is actually able to
        switch the EGA monitor between two separate modes: The CGA's
        horizontal sweep rate of 15,750 cycles per second and the newly
        invented EGA horizontal rate of 21,800 cycles per second. The
        15,750 hertz rate yields a CGA software compatible resolution of
        200 lines, while the 21,800 hertz rate results in a full
        Hercules-type resolution of 350 lines. In EGA graphics mode, this
        results in a significant, Hercules-similar resolution of 640
        by 350 pixels.

        Since IBM seems determined not to kick the horizontal resolution
        of these systems up above 640 pixels, we don't quite get the full
        character separation beauty of MDA and Hercules text. On the
        other hand, the EGA's character resolution budget
        of 8 by 14 pixels is significantly better than the CGA budget of
        8 by 8 and allows lower case characters with descending tails
        like "g," "p," "q," and "y" to be imaged cleanly. The EGA's
        resulting well-formed characters made most people happy.

        The EGA's final addition to the CGA standard was the provision
        for additional colors. Where the CGA display could display 8
        colors in either of two intensities, bright or dim, the EGA
        display, when operating in EGA mode, allowed each of its three
        primary colors, Red, Green, and Blue, to be mixed together in
        any of four intensities. Therefore 4 times 4 times 4, or 64
        total colors could be displayed by IBM's EGA display. Though
        technology has passed the EGA monitor by, it represented an
        adequate, backward compatible, unification of the CGA, MDA, and
        Hercules standards.


                   IBM's recognition of the EGA's shortcomings
                     with the creation of the VGA "standard"


        On our journey toward the goal of selecting the best possible
        display system for the least possible money for Steve's Dream
        Machine, we've traced the evolution of IBM compatible display
        system technology from the original CGA and MDA standards
        through the development of the Hercules and EGA standards. IBM's
        announcement of its new generation PS/2 machines offers yet
        another display system to "the standard" throne. Oddly named
        after the integrated circuit chip which implements it, the Video
        Graphics Array, or VGA, has provided enough new cleverness and
        innovation to displace the prior EGA standard.

        With graphic user interfaces gaining ever more market
        recognition and IBM's own OS/2 Presentation Manager on the
        horizon, IBM needed to push their graphics resolution offering
        above the EGA's 640 by 350. At the same time, IBM wished to
        further enhance the system's color capabilities, probably to
        further differentiate itself from Apple Computer's
        monochrome Macintosh products and to better compete with Apple's
        newer colorful Mac II. To further confuse things, this was all
        happening at a time when IBM was determined to lower its
        manufacturing costs.

        While the EGA display was innovative with its split-personality
        dual-frequency horizontal sweep rate in order to deliver both
        350 line vertical resolution without sacrificing 200 line CGA
        compatibility, is was more expensive to manufacture than IBM was
        now happy with. IBM made a brilliant move in their VGA system
        which completely eliminated the need
        for the expensive frequency changing display while actually
        enhancing the appearance of older CGA-style text and graphics.

        The VGA's fixed horizontal sweep rate of 31,500 cycles per
        second offers several wonderfully clever savings. In the first
        place, dividing the horizontal rate of 31,500 hertz by the 60
        cycle vertical rate yields 525 total horizontal lines scannable
        during one screen. This high scan line count delivers even
        better legibility from VGA text which now has a text character
        pixel budget of 8 by 16, while the EGA's barely adequate high
        resolution line count of 350 jumps up to a very respectable 480.
        The excess line count (the difference between the 525 total and
        the 480 used) even allows a tidy 1/4 inch border in all modes.

        The VGA's cleverness stems from two additional things which IBM
        did in order to deliver backward compatibility to the CGA and
        VGA. The VGA monitor's very fast horizontal scan rate put IBM in
        the enviable position of actually having, in some cases, too
        many scan lines, rather than too few. So in such cases IBM
        slightly INCREASES the vertical refresh rate (to above 60 hertz)
        in order to trim back on the number of lines displayed when they
        need fewer.

        Secondly, rather than slowing the display's HORIZONTAL rate
        drastically down to the CGA's 15,750 cycles, in order to deliver
        just 200 horizontal scan lines, the VGA raises its VERTICAL rate
        just slightly up to 70 hertz which yields 400 scan lines. Then a
        clever double-scanning approach is used to emulate the CGA's 200
        line mode. Double scanning simply repeats each of the CGA's
        lines twice and results in a higher resolution appearance while
        maintaining complete software backward compatibility.

        The only remaining "tweak" required involves keeping the VGA's
        displayed screen height constant which the IBM VGA monitor
        achieves by sensing the polarity of the Vertical Synchronization
        signal sent to it by the VGA adapter. The monitor uses the
        Vertical Sync signal polarity to adjust the spacing between
        successive scan lines so that the VGA's image is kept almost
        uniformly sized throughout the increasing jungle of new, old,
        and older display modes.

        Thus the VGA system scans 350, 400, and 480 lines to achieve
        CGA, EGA, and VGA compatible display modes while leaving the
        horizontal scanning rate set to a constant 31,500 hertz and only
        tweaking the vertical refresh rate between a happy 60 and 70
        cycles per second. The result is a simpler and far less
        expensive VGA monitor which exceeds the EGA's capabilities and
        delivers far cleaner CGA emulation.

        The other major change presented by the VGA system is an
        expansion of the system's color capabilities. The original CGA
        monitor utilized one signal each for Red, Blue, and Green
        colors, and an additional single signal for intensity which
        delivered 16 total possible colors. The EGA expanded upon this
        by providing two signals each for the Red, Green, and Blue
        colors, thus delivering four intensities of each color, with 64
        color mixtures possible. The VGA's color system operates in an
        ANALOG rather than DIGITAL fashion where varying voltages, rather
        than ON/OFF signals are provided for each color for mixing.
        Software and memory limitations pare the resulting infinite
        color possibilities down to a maximum of 256 colors chosen from
        a total palette of 262,144 in some display modes.


                   NEC's Brilliant Creation of the Multisync,
                       and 800 by 600 Resolution Graphics


        We've taken a detailed look at the evolution of IBM compatible
        display systems, focussing almost exclusively upon the multitude
        of standards which have first been set then soon superseded by
        IBM. We've seen that the various display adapters have always
        been "tightly coupled" to their display monitors and have
        frequently employed fancy "kludge" solutions (like conditional
        inverting of synchronization signal polarities) when necessary
        to maintain backward compatibility to the multitude of prior
        standards.

        Amid the wilderness created by the incredible array of vertical
        and horizontal scan rates, a solid alternative to the eternal IBM
        lock-step frenzy has arisen. Originally conceived by Nippon
        Electric Corporation (NEC) as an answer to just this problem, the
        so-called "multi-synchronous" display monitors are now selling in
        the hundreds of thousands for a very good reason.

        In what could only be called a truly astounding leap of insight,
        the designers at NEC integrated the past and predicted the
        future when they invented their original NEC Multisync, a single
        unified display monitor solution for all adapter technologies
        past, present, and future. Rather than following IBM with yet
        another tightly coupled clone display monitor, NEC invented a
        single monitor which quietly displayed anything it might be
        handed by the system's display adapter. By accepting an unheard
        of range of vertical and horizontal synchronization frequencies,
        as well as both digital and analog RGB intensity signals, the
        NEC Multisync became virtually obsolescence-proof.

        While IBM was busily requiring all of its EGA owners to
        completely scrap their "yesterday's solution," EGA monitors which
        would no longer be compatible with the VGA of today (and
        tomorrow?), and purchase the all new VGA displays, proud
        Multisync owners only needed to change their monitor's cable
        then flip a couple of switches at the rear of their displays.
        That's what I call truly brilliant engineering!

        Of course it wasn't long until everyone else recognized NEC's
        brilliance and began cloning multisynchronous monitors like mad.
        Today's mail order ads are drenched in "generic multisynch-ness"
        because it's simply the right way to go.

        However, there's something else which makes multisynching the
        right solution, and after extensive experimentation and
        comparison it has become an INFINITELY CRITICAL COMPONENT of
        Steve's Dream Machine: Support of the wonderful 800 x 600 pixel
        super high resolution modes which are now available from all
        state-of-the-art EGA and VGA display adapters.

        Many of you will remember that Steve's Dream Machine and I have
        been holding onto monochrome display technology for dear life...
        looking to monitors such as the Wyse-700/Amdek-1280 and MDS
        Genius to provide the truly useful bit-mapped graphics
        resolution which is, and will be, required by today's and
        tomorrow's desktop publishing, MS Windows, and OS/2 Presentation
        Manager applications. Until many months of searching yielded the
        incredible, ultimate, adapter/monitor combination, I didn't
        believe that a color system could really deliver "truly useful"
        (and in fact wonderful) high resolution bit-mapped displays. It
        can. I'll tell you about the results of my quest, but first we
        need a bit more foundation...

        It turns out that truly useful bit-mapped resolution requires
        stepping above even the VGA's new 640 by 480 resolution up to
        800 by 600. By cranking the horizontal sync up to 35,100 and
        sneaking the vertical refresh just a tad below 60 hertz to about
        56, any solid multisynchronous monitor can readily display 600
        lines of 800 full color pixels per line.

        There's something magical about the difference between 640 by
        350, 640 by 480, and 800 by 600. It's a staggering difference.
        The prior two resolutions simply pale by comparison to 800 by
        600. Trying to understand why things get so incredibly better as
        the resolutions are increased, I've decided that it's because
        the total pixel count increases with the PRODUCT of the
        horizontal and vertical resolutions. This is a powerful
        relationship. For example, on a screen with square resolution,
        the total pixel count would increase with the SQUARE of the
        screen's edge resolution, so a DOUBLING of edge resolution
        produces a QUADRUPLING of the total pixel count. Consequently
        the standard EGA resolution of 640 by 350 contains only 46% of
        the pixel count of 800 by 600, and even the VGA offers only 64%.
        800 by 600 resolution delivers 156% of the VGA's pixel count.

        So at this juncture we must leave IBM in the dust. Only enhanced
        EGA and VGA adapters are able to generate 800 by 600 pixels, and
        only multisynchronous displays can lock onto the extreme
        synchronization frequencies required for the delivery of this
        stunning and readily available resolution.


                        The Incredible SONY CDP-1302A...
                    Steve's Dream Machine Monitor of Choice!



        Having decided that Steve's Dream Machine monitor had to be
        multisynchronous in order to deliver the most resolution
        possible, the next obvious question was: Which one was the best?
        After staring endlessly at, and touching and feeling, just about
        every available candidate, I determined that no other monitor
        comes anywhere NEAR the quality of the Sony "Multiscan" CDP-
        1302A. The Sony Multiscan is solidly entrenched as the Steve's
        Dream Machine video display monitor. After purchasing several, I
        couldn't be more pleased.

        The single feature which distinguishes the CDP-1302A from the
        crowd, placing it heads and shoulders above the rest, is its
        image quality. Based upon Sony's legendary Trinitron color
        picture tube, the 1302A packs its primary red, blue, and green
        phosphors so closely together that white text actually looks
        white, rather than appearing as an ugly island of white fringed
        with red on one side, green on top, and blue on the other side.

        Coming from the purely monochrome character coloring of
        monochrome displays as I did, I just wasn't willing to sacrifice
        text color purity for the sake of color. The Sony 1302A is the
        ONLY monitor in the industry which doesn't compromise text
        appearance for color capability. As I write this column with PC-
        Write, I'm staring at white text on a blue background. With my
        nose one inch from the screen, aside from being cross-eyed, I
        absolutely cannot see anything but white text on a blue
        background. No other monitor delivers this quality.

        All contemporary color monitors operate through a process known
        as "SPATIAL COLOR MIXING." Though from a distance the screen
        appears smooth, homogeneous and continuous, it's actually
        composed of thousands of individual red, green, and blue
        phosphor regions. When the display's electron beams strike the
        phosphors from behind they fluoresce and glow in one of the three
        primary colors. By controlling the instantaneous voltages applied
        to each of the three electron beams at the back of the CRT, the
        red, green, and blue color phosphors in the region
        where the beams are striking are made to glow in proportionate
        brightness.

        Our eyes, having somewhat limited resolution, don't see the
        individual red, green, and blue phosphors in the region, but
        instead spatially mix these colors into a single composite.

        (It's rather incredible to realize then that the first thing our
        eyes do is to re-separate this composite color back into its
        red, green, and blue color levels since our eyes are built from
        light sensitive rods and cones which selectively respond only to
        red, green, and blue light!)

        However, our eye's ability to convincingly spatially mix the
        screen's primary colors is a function of the center-to-center
        inter-color spacing, which is also known as the display's "DOT
        PITCH." Not only does the Sony have a significantly tighter dot
        pitch than any other large display in the industry (0.26
        millimeters versus 0.31 or coarser for everyone else), but the
        Sony's Trinitron'ness seems inherently better suited to the job
        of helping our eyes to perform this mixing. It's almost as if
        the individual colors are being pre-mixed behind the screen
        before leaking out onto the tube's glass faceplate.

        This dot pitch also means quite a lot when the monitor is being
        called upon to display higher resolution images. As the number
        of displayed pixels per inch begins to approach the number of
        phosphor dots per inch a strange interaction known as "SPATIAL
        FREQUENCY BEATING" occurs. You can most easily see this by
        drawing single pixel wide horizontal, vertical, or slanted black
        lines against a solid white background. Rather than appearing as
        black, the line's width is so much smaller than the surrounding
        illuminated pixels that these too-fat pixels bleed their colors
        into the supposedly black line, rendering a non-black dimly
        colored line. In practice, high resolution black on white
        applications such as desktop publishing end up appearing
        disturbingly multi-colored rather than pleasingly black on
        white. The 800 by 600 pixel resolution which multisync displays
        provide at no cost requires the dot pitch to be as tight as
        possible.

        If you care about your eyes, I urge you to check into the Sony
        Multiscan CDP-1302A. This is NOT a place to compromise.



                         And the Paradise VGA Plus Card,
                       The Ultimate VALUE in VGA Adapters


        Having answered the burning question of the ultimate video
        monitor for Steve's Dream Machine with my enthusiastic ravings
        about the marvelous Sony CDP-1302A multiscan monitor, the final
        question to be answered for our display sub-system project is:
        What's the ultimate display adapter?

        Determining the correct answer to this question was complicated
        substantially by the simple fact that the VGA marketplace is
        filled with an incredible degree of clutter, misdirection,
        overstatement, and outright lies. What you see and hear is
        almost always FAR FAR different from what you actually get. Wild
        claims made by VGA adapter manufacturers abound, the ads are
        largely full of baloney, and it's quite hard to really know
        what's true. It's also quite hard to know what really makes a
        DIFFERENCE in VGA adapters, so consequently even the normally
        shrewd buyer will wind up guessing.

        As my research into VGA adapters progressed, and I learned more
        and more, I became increasingly upset by the state of affairs and
        committed a disproportionate amount of time and energy to
        the task of finding out what's REALLY going on. Getting
        underneath the covers to substantiate or debunk various claims
        required the creation of special benchmarking software to
        directly measure critical adapter parameters such as horizontal
        sweep rates, overall vertical refresh rates, and raw low-level
        adapter data bandwidths. What I discovered amazed me, and even
        though the results of this research may upset some significant
        players in the industry, I feel compelled to share what I found.

        Since I don't want to tease you any more than necessary, I'm
        telling you right up front, here and now, that for my money,
        there is no adapter in the industry which delivers more overall
        value than the inexpensive, analog-only, 8-bit, incredible
        Paradise VGA Plus. Though the VGA Plus is currently in very
        short supply, being affected both by its own popularity as well
        as by our industry's current dynamic RAM shortage, it's an
        incredible value at its current street price of between $230 and
        $260.

        I urge you not to purchase any other display adapter, VGA or
        otherwise, until you've heard me out. Though you might have to
        struggle and/or wait a while to find one, it'll be a decision
        you couldn't regret.

        The various VGA adapters in the industry may be differentiated
        by applying the following tests and comparisons: raw low-level
        data bandwidth, companion software drivers, display monitor
        compatibility, IBM VGA register level compatibility, system-
        level hardware compatibility, and to a lesser degree backward
        compatibility with prior display standards.

        Of all these characteristics, only video display compatibility
        and backward compatibility are obvious from the surface. Every
        other characteristic must be determined through actual use and
        testing. The only negative feature of the Paradise VGA Plus in
        this regard is it's total lack of support for the older digital-
        only monitors including the original IBM monochrome, CGA, and
        EGA displays. You won't be able to use the VGA Plus if you have
        one of these, though Paradise has stated that they will make a
        version of their card for sale to large OEM customers which will
        support both digital and analog monitors. This liability is
        shared by the Compaq and Video Seven Fastwrite and VRAM cards,
        so the Paradise is in good company. Of course this is no problem
        if you already own or intend to purchase any multisync monitor
        like Steve's dream monitor, the Sony CDP-1302A.

        Almost every VGA adapter in the industry is a so-called "five-
        in-one" card. Five-in-one refers to MDA, CGA, Hercules, EGA, and
        VGA, and means that such cards can run virtually any software
        ever written to any of these major standards. The two notable
        exceptions are IBM and Compaq which lack support for the
        Hercules standard. Even though Compaq's VGA adapter utilizes the
        Paradise PVGA1A VGA chip, and could thus have easily implemented
        Hercules backwards compatibility and the useful extended
        resolutions as do the Paradise VGAs, Compaq chose not to bring
        these features to their purchasers, apparently preferring to
        remain more strictly IBM compatible. For this reason, and
        considering its high price, you'd have to really love the Compaq
        name in order to intelligently purchase Compaq's VGA adapter.
        It's a very nice adapter, but the Paradise Plus or Pro do more,
        cost less, and are otherwise identical, all being based upon the
        same VGA chip.



                           Display System Performance


        It's hardly surprising that the single hottest issue in the VGA
        marketplace is performance. People want machines that don't
        slow them down, and since our video display screens are the
        windows into the souls of our machines, it's only natural to
        want a screen that can keep up with the CPU which lurks behind.

        Being a performance fanatic myself, the first thing I did was to
        write a machine language benchmarking program to determine the
        fundamental raw machine-level data throughput of VGA adapters.
        As a low-end reference point, the true Blue IBM VGA adapter can
        accept text data at 569 Kbytes per second and graphics data, when
        in 640 by 480 resolution, at 592 Kbytes per second.

        The IBM's raw text throughput of 569 Kbytes per second means
        that the entire 4000 byte text screen could be re-written 142
        times per second. Since display screens are only displayed 60 to
        70 times per second, anything faster than this is completely
        invisible and represents wasted performance. The point is, when
        displaying a 25 line by 80 column text screen, even the SLOWEST
        VGA card on the market (which the IBM VGA is) is twice faster
        than is even visible! Those "8 times faster" performance claims
        being made by several VGA competitors are based upon their
        card's text-mode throughput and are about as useful as a jet
        engine on a skateboard. I ignore such nonsense and the companies
        behind it.

        However, what's true for text mode performance is not
        necessarily true for bit-mapped graphics. While an entire text
        screen is specified by just 4000 bytes of data, a 16-color 800 by
        600 high resolution bit-mapped image requires 240,000 bytes of
        data! Even so, IBM's 592 Kbytes of graphics throughput can still
        paint an entire VGA image in four-tenths of one second. That
        really isn't bad.

        So how do the other boards in the market compare? Well any board
        based upon the Tseng Labs (pronounced sang) chipset will deliver
        approximately IBM-grade performance. Tseng Labs based boards
        such as those from Genoa, Orchid, Sigma, STB, and Tecmar have
        throughputs of 591 Kbytes for text and 588 Kbytes for graphics,
        which is actually a bit slower than IBM. The advantage these
        boards have over the IBM is 5-in-1 backwards compatibility.
        Unfortunately, this comes with an expense of yawning performance.
        Several also utilize the Tseng Labs 1024 by 768 resolution mode.
        This requires display screen interlacing which halves the overall
        refresh rate and produces completely unacceptable display flicker
        when using Ventura or with Window's color mixing scheme known as
        dithering.  One positive feature of these cards is their full
        support for the digital-only MDA, CGA, and EGA monitors, but
        since such monitors aren't state-of-the-art anyway, it would be a
        shame to choose a poor performing VGA adapter for the sake of
        running a poor performing display. For these reasons, I don't
        recommend Tseng Labs chip based VGA adapters.

        Video Seven has been generating quite a lot of press attention
        lately with their FastWrite and VRAM VGA adapters. Having
        studied these boards at length with the hope that they would
        turn out to be real screamers, I have to admit to being less
        than fully impressed. I had significant hardware and software
        incompatibility problems with the FastWrite and VRAM boards and
        none with any others. Though I've heard that newer revisions
        have solved many of the earlier problems, I still feel shy toward
        them.  Also, the incompatible way their video BIOS was designed
        prevents multitasking software from freely and properly
        switching tasks between various extended modes. This alone would
        keep me away from Video Seven's products.

        However, it can't be denied that the Video Seven pair are
        uncontested winners when raw throughput alone is considered. In
        640 x 480 mode, the FastWrite came in with 1.812 megabytes per
        second throughput, and the VRAM delivered a screaming 2.885
        megabytes per second.

        I was puzzled at this point because my favorite little Paradise
        Plus board, with its 1.139 megabytes per second throughput, just
        didn't SEEM to be any slower than the VRAM. It occurred to me
        that the board's raw throughput was being "watered down" by
        "software overhead" which would tend to equalize performance.
        After writing a new set of benchmarks to test performance
        THROUGH their respective Windows drivers, I found what I
        expected. Despite the fact that the VRAM board could accept raw
        bit-map data 153% faster than the Paradise Plus, the software
        overhead in the Windows drivers resulted in a performance
        difference of only 54%! When the application's own overhead was
        factored into this, the VRAM edge was even further blunted.

        Due to architectural characteristics of the Paradise PVGA1A VGA
        chip, Paradise's 16-bit boards actually deliver NO MORE
        PERFORMANCE than the inexpensive 8-bit Paradise Plus, Steve's
        Dream Machine VGA board.



                            The Display System Series
                                   Loose Ends



        Let's finish our study of the state of the art in IBM video
        display technology by tying down a variety of loose ends. As
        we've seen, my display adapter of choice is Paradise's 8-bit VGA
        Plus. Surprisingly, the architecture of the PVGA1A chip, which
        forms the heart of every VGA adapter from Paradise as well as
        the VGA systems produced by AST Research and Compaq, gains
        NOTHING from a 16-bit bus connector when the boards are used in
        their high resolution bit-mapped modes. This means that except
        for the additional memory on the Paradise VGA Pro board, there's
        absolutely no benefit to purchasing it over the less expensive
        8-bit Paradise Plus. In fact, the temptation would then be to
        run the Pro card in its 256 color mode, but my benchmarks
        revealed that display performance suffers with higher color
        counts. This is hardly surprising since additional colors depend
        upon the use of additional memory which must be managed by the
        driving software.

        After declaring the Sony "Multiscan" CDP-1302A to be today's
        ultimate video display, I was contacted by many competing vendors
        who wanted me to believe that their displays were better. As a
        result of entertaining several such possibilities I'm more
        certain now than ever that the Sony blows EVERYTHING else away.

        As I acquire increasing experience with 800 by 600 resolution,
        which you get "free" when the Sony is paired with the Paradise
        VGA Plus, I'm becoming more and more certain that it's ultimately
        the best general purpose resolution. When running at 800 by 600
        resolution, the Sony produces an active image area which is 10
        inches wide by 7.5 inches tall. Dividing each of these lengths
        into the pixel resolution in that dimension yields exactly 80
        pixels per inch IN EACH DIRECTION. This beats the Macintosh's 72
        ppi resolution with a much larger screen while delivering the
        Macintosh's popular "square" pixels which are exactly as wide as
        they are tall. It's nice to have a system on which circles
        appear circular and squares really are square!

        While I'm thinking about high resolution under Microsoft
        Windows, I really need to make sure you know about Micrografx's
        incredible Designer product. Designer feels to me like a highly
        evolved CAD package with an exquisite state-of-the-art Windows
        user interface. Using Designer has become fast and reflexive. It
        has that rare easy-to-learn feeling which results from several
        generations of detail polishing. While Designer completely
        answers my desire for the lightning fast creation of structured
        graphics, I've been surprised and delighted to find that several
        of my died-in-the-wool traditional "CAD freak" friends have
        completely switched to Designer after seeing me mouse my way
        around it. If you have any need for PC based drawing, I'd urge
        you to take a peek at Micrografx's Designer.

        I'm addicted to Ventura Publisher for the creation of all manner
        of high grade hard copy, so the quality and legibility of
        Ventura's displayed image has profound importance for me. If
        you've been reading this column for long, you probably know that
        I tend toward perfectionism, always needing to get the most out
        of my system. So I've been irked by Ventura's three fixed
        display screen zoom factors. At each zoom setting the image is
        always either too small, leaving an unused "grey zone" to the
        right of the page's image, or too large, requiring a horizontal
        scroll to see everything.

        Bitstream Inc. has developed and sells a fabulous technology
        called FONTWARE which generates any size and resolution of
        ultra-high-quality typefaces from a set of sophisticated
        typeface outline masters. Since the EGA's pixels aren't square,
        the EGA-compatible screen fonts which are shipped with Ventura
        aren't specifically tailored for 800 by 600 resolution. So I
        decided to used Bitstream's Fontware to regenerate an entirely
        new set of Ventura screen fonts with SQUARE pixels, and while I
        was at it, to choose a screen font resolution which would give
        me EXACTLY the Ventura zoomed sizes I wanted.

        After some experimentation, I'm delighted to tell you that I now
        have exactly what I want from Ventura. By asking Bitstream's
        Fontware technology to rebuild Ventura's screen fonts at 100 by
        100 pixel resolution the text of a standard 8.5 by 11 inch page
        with one inch margins EXACTLY FILLS the screen in Ventura's
        "normal" viewing mode with Ventura's mode selection icons
        displayed. The result is an incredibly clear and legible image
        in 800 by 600 resolution which puts the VGA's defacto 640 by 480
        image to shame.

        Micrografx can be contacted about Designer at (800) 272-3729 and
        Bitstream can tell you more about Fontware at (800) 522-3668.

                                   - The End -

                     Copyright (c) 1989 by Steven M. Gibson
                             Laguna Hills, CA 92653
                            **ALL RIGHTS RESERVED **



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