by March 31, 1998 0 comments

Along with the monitor,
the display adapter (or video card as it is commonly
referred to) determines the picture quality of your
computer. If you’re a computer junkie who spends
between eight and fifteen hours a day staring into the
screen, its definitely worth spending that extra bit to
get a sharp, clear, and stable image. Even if you’re
not, the benefits of a decent video card soon become
apparent, especially in a multitasking environment, such
as Win 95, or if you play lots of games.

 
Powerful
2D accelerators, such as the Millenium II, are
the ideal choice for most graphics intensive
applications
 

Display cards,
however, is one area where just bigger, better, and
faster won’t necessarily help you. These cards are
available for a wide variety of applications. Simply
buying the fastest card won’t help because you would
probably never use most of its features.

These cards are basically
of three types. The old unaccelerated type, such as early
Cirrus Logic and Trident cards; those which incorporate
2D acceleration, such as the Matrox Millenium, Diamond
Stealth, and (on the lower end) the S3 Trio family; and
finally the new breed of high-end 3D accelerators. At the
high end, you have two further sub-divisions, those like
the RIVA and Voodoo, which are typically used for gaming,
and those based on 3D Labs chipsets, such as the Permedia
2, used for high-end 3D modeling.

Simply put, buying an
unaccelerated card today does not make any sense for any
user. Irrespective of what you use your computer for, you
will be far better off choosing a card that offers high
resolutions and refresh rates to protect eyes strain
commonly caused by working with low refresh rates and
cheap monitors.

To understand the
advantages of an accelerator, you need to understand what
goes into producing even a simple movement on the screen.
A common example is of dragging a window with its
contents showing, as allowed by the Microsoft Plus! pack.
As you drag a window, the computer has to perform a large
number of matrix calculations that determine the current
location of the window, create it in memory, and then
copy it to the video frame buffer to be displayed on the
screen. On an unaccelerated system, the CPU has to
perform these calculations, which means that even a
slightly older Pentium struggles to cleanly move the
window without jerkiness or visible screen redrawing. On
a system with an accelerated display adapter, however,
the card intercepts the bitblt and stretchblt
API calls used to move the image, and implements it
directly on the frame buffer of the display card. As a
result, the CPU is let free to process other tasks while
the window is dragged smoothly. This is perhaps the
simplest form of acceleration, performed by almost any
card you can buy today. Other acceleration features
include X and Y scaling to allow videos to run smoothly
at any resolution, and hardware MPEG decoding implemented
on some of the more expensive cards.3D accelerators are more
complex. They are required to implement hundreds of
functions of the DirectX and OpenGL APIs to create fast
and realistic animations. There are divisions even within
this category. High-end workstation-class cards usually
support only the OpenGL API, which is the standard for
advanced 3D modeling and rendering. The new breed of
gamers cards, however, are optimized purely for games,
and usually support Microsoft’s DirectX API and
other proprietary APIs used mainly for gaming. (For more
information see PC Quest February 1998.)

It’s important to
decide what you need and match it to your computer’s
capabilities before you choose a card. If you’re a
graphics designer or even involved purely with CAD work,
you stand to gain very little or even nothing by going in
for a 3D accelerator. However, you will benefit
enormously from a fast 2D accelerator, such as the Matrox
Millenium II.

The average user will want
a card that is capable of displaying resolutions of up to
1024×768 at high color on a 15" or 17" monitor.
An important aspect of the card to look at is the refresh
rates it produces. Based on your monitor and
applications, you should determine the kind of
resolutions and color depths you are going to be working
at, and check that the card is capable of supplying high
refresh rates (above 75 Hz) for all but the very highest
of those resolutions. Refresh rates of display card are
dependent on two factors: the type of memory used and the
RAMDAC. A fast RAMDAC, in the region of 150..250 Hz, is
recommended as they can provide refresh rates to satisfy
almost any monitor. The type of memory is important as it
determines the overall performance of the card. DRAM is
now totally out. Almost all newer cards use either EDO
RAM or VRAM, with SGRAM (which is the graphics equivalent
of SDRAM) fast becoming more popular. Many manufacturers
still stick to their own proprietary technologies, such
as MDRAM, WRAM, etc, which provide adequate performance.

Like any other component,
a good display adapter goes a long way in improving the
overall look, feel, and performance of your system.
Choosing the right card not only increases your
productivity, but saves you from the discomfort of
squinting into a dim screen with a poorly formed image.

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