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Choosing A Display Adapter

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PCQ Bureau
New Update

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.

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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.

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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

1024x768 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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