Re: CMD products for GS (NTSC->RGB?, Scan Doublers, 20MHz)

[supertimer@aol.com (Supertimer)]

Someone said that if CMD was interested in tapping the GS market,
it would be more interested if there was a product already
designed that they could build with no additional R&D.  There is
also talk that the Second Sight card is not the best that the GS
can do.  Presenting the TurboRez GS card, by RezTek.  TurboRez is
a fully designed graphics accelerator card for the GS.  After
spending years designing and redesigning the card, the designer
shelved the project because the Second Sight beat them to the
market.  Today, many people express distain for the Second Sight's
performance.  The designer of the TurboRez had misjuged the
market.  They had the better card and had the TurboRez been made,
it would be the dominant card today.  Many people still yearn for
a better graphics card.  CMD (or Alltech or others) has a chance
to pick up this fully designed, ready to manufacture card and
provide the GS community with a new product.  This card offers
new capabilities and has a market in the GS community where many
users want better video but reject the Second Sight for its
limitations.  CMD has shown that a market still exist in an
orphaned platform like the Commodore 64 and 128.  The GS community
is a similar group of hackers, waiting to be wowed.  If you are
interested in building for us, there is a market here.


PRESENTING THE TURBOREZ GS


AN OVERVIEW
        The TurboRez GS card is a circuit board that plugs into one
of the 7 peripheral slots inside the IIGS. It's RGB video output
(Turbo HiRes or THR) is merged with the SHR video on the GS
motherboard. They both leave on the standard RGB video port at the
rear of the GS. Until the TurboRez card is activated by an
application that's aware of its presence, it stays in the
background and doesn't interfere with normal GS operations. Which
brings up the question: Are existing applications automatically
enhanced by the TurboRez card? The answer is no and the main
reason is that when those applications were originally written,
cards like the TurboRez didn't yet exist.

        TurboRez can generate a 256 color display (That is, it can
display up to 256 colors on a line versus the stock GS's 16 color
per line limitation). This applies to both the 320 and the 640
display modes. There's also an extended palette feature that
allows up to 7000+ colors onscreen. This is done in a somewhat
similar fashion as the "3200" color mode used on the stock SHR
display, except that with TurboRez it's totally handled by the
hardware (so no software loading). Here, you have the advantage of
additional shading capability and yet retain the ability to do
palette-cycling for "cheap but fast" animation (Something you
give up when using a "True-Color" display).

        In addition to the standard 200 line (vertical) display
mode, there's also an interlaced 400 line mode available. This
works on a stock GS RGB monitor. There's also the ability to switch
into a true Overscan mode. This makes it possible to extend the
display to fill up the monitor screen completely (Extra pixels are
added to do this). Note: A 640 mode VGA adaptor is available
separately.

MULTIPLANE TECHNOLOGY
        On a typical Single Plane display system, animated
"sprites" or "shapes" pass over or under each other, or in front of
or behind fixed scenery in the background image. To make all of
this appear seamless, the application software has to stay very
busy not only erasing and redrawing the sprite of interest every
time it's to be moved, but also any other sprite or scene element
that it happens to overlap (even if those other objects are not due
to be moved during this frame). As you might imagine, all of this
activity slows the CPU down tremendously
        On a MultiPlane display, there can be several separate
images that overlay one another. Modifying one of them doesn't
affect the contents of the others. This reduces or eliminates
the duplicated and timewasting gyrations necessary on a single
plane system.

A BLITTER, YOU SAY?
        The term "blitter" comes from an obscure acronym used on
earlier graphic hardware. It's commonly accepted meaning is
basically the act of efficiently moving groups of pixel data from
from one place in memory to another. During this process, the pixel
data can be modified if needed. For instance, "transparent" pixels
could be detected and not written, or the source bitmap could be
scaled as it's being read. The key is to move image data as fast as
possible. A higher transfer speed means larger shapes can be drawn
and/or higher animation frame rates can be maintained (i.e.
"smoother" motion).

        Now, a CPU chip can execute code and operate as a "software
blitter" but, as is the case with other functions, dedicated
hardware can easily outperform it. As an example, the Second Sight's
onboard CPU is capable of software blitting at about
4 megapixels/sec (1 pixel=1 byte). On a TurboRez card with .5 meg of
ram, the hardware blitter can transfer at 16 megapixels/sec, about 4
times faster. On a TurboRez with 1 meg of ram, the blitter can
achieve 32 megapixels/sec, or about 8 times as fast.

        In the above example, we're only dealing with straight
blitting. That is, we're only talking about reading pixels from one
place and writing them to another without doing any kind of
modifications. For a software blitter, this is as good as it gets
because, to modily the pixel data as we "blit" it, means adding
more instructions for the CPU to execute (per pixel). In the case
of the transparent source pixel detect or in the process of scaling
a source bitmap (shrinking or expanding it), the software blitter
takes a big hit in performance. Now, instead of 4 megapixels/sec,
we drop to about .5 megapixels/sec (with the software blitter).

        Ah, but even while performing scaling or transparent pixel
detect operations, the TurboRez's hardware blitter still operates
at its normal speed, it doesn't suffer from the "extra" workload. So
comparisons now reveal TurboRez performance as being anywhere from
32(16/.5) to 64(32/.5) times faster than the Second Sight, under
these conditions.

LINE DRAWING, SCALING AND ROTATION
        The TurboRez's hardware line drawing feature shares the
blitter circuitry and so it has similar performance specifications.
Again, this is because the process of drawing a sloped line involves
a heavier workload for a software blitter, whereas a hardware
blitter takes it in stride. Because the TurboRez line drawing
hardware can scale (shrink/expand) a source bitmap as it drwws, we
gain the ability to Scale with Rotation. This is extremely useful
for many drawing and animation tasks. It allows us to use a master
set of bitmaps and then modify them in "real time" as they're being
drawn. Say, for instance, a spinning object that approaches and
recedes.

        This Scaling and Rotation capability also comes in handy for
"texture mapping" operations. This is a process where a source
bitmap is applied to the face of an onscreen object, much like
sticking a decal on a plastic model. In this way, a pseudo 3D scene
can be built up onscreen in a very rapid manner. Many popular games
on the PC ("Doom", for one) use techniques similar to this to
generate virtual worlds for gameplayers to explore and interact
with. With TurboRez's fast hardware drawing power, GS users will be
able to experience full-screen, high frame-rate, texture mapped
environments.

        Why the overiding concern with drawing speed? Think about
it: A 320 by 200 byte-per-pixel display is about 60K in size. A 640
by 400 display is 4 times that, a whopping 240K! Since realistic
animation demands frame rates of 15 per second and higher, dealing
with display memory buffers this big requires some pixel moving
muscle. And that's where TurboRez comes in....

CONTACT INFORMATION:
RezTek owns the design to the TurboRez card.

RezTek
2301 Cotton Ct
Santa Rosa, Ca 95401
707-573-9257

Last known email address: REZTEK@GENIE.COM