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AGP
Accelerated graphics port. The standard PC interface for videocards. The current spec is AGP 8x, which provides
about 2.1GB/s of bandwidth between the videocard and motherboard chipset.
AGP APERTURE SIZE:
The amount of system memory an AGP videocard can use for storing 3D information.
AGP FAST WRITES:
Enabling AGP Fast Writes lets a program access the videocard directly, instead of through system memory. This reduces
bandwidth demands on the bus.
AGP PRO:
A beefy version of the AGP interface designed to deliver extra power to workstation-class videocards. AGP Pro uses
a slightly longer AGP slot, and comes in two flavors, 50-watt and 110-watt. Current consumer accelerators from
ATI and nVidia use an onboard Molex connector to draw additional power, because the AGP Pro interface isn't ubiquitous.
ALPHA CHANNEL:
Every pixel in a game is described by four color channels: R, G, B and alpha. The first three channels store data
on the pixel's mixture of red, green and blue, while the alpha channel describes a pixel's relative opacity. In
32-bit integer color, the alpha value is contained in the last 8-bits of the pixel's color info.
ANISOTROPIC FILTERING:
An advanced filtering technique that corrects a texture's perspective when the texture is drawn on an object that
stretches deep into a scene.
ANTIALIASING:
Any technique used to smooth jagged edges that are created when straight lines are drawn in 3D game or program.
API:
Application programming interface-basically a set of rules and routines that developers can use to design games
and applications. APIs provide programmers with a set of pre-defined function calls that can be used for basic
tasks, such as drawing windows and buttons, or advanced operations, like applying a bump map to a polygon.
The most basic filtering strategy, bilinear filtering reduces texture pixelization by blending adjoining textures at their seams. Modern 3D accelerators use bilinear filtering by default.
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CG:
nVidias high-level shaded language. It includes all the functions of Microsoft's high-level shader language(HLSL),
as well as some functions specific to nVidia GPUs.
CORE CLOCK:
The speed at which a 3D card;s graphics chip runs, usually measured in megahertz(MHz).
DB-15:
The standard 15-pin connector for analog monitors. If you use a CRT or analog LCD monitor, this is the connector
you use.
DDR:
Double data rate, usually used to describe memory. DDR memory can transfer two chunks of data every clock cycle,
a "double-pumped" strategy that effectively double memory speed.
DDR-II:
The latest version of DDR memory. DDR-II memory doesn't transfer more data per clock cycle than the original DDR
memory, but it has been modified to run at much higher clock speeds than plain DDR.
DIRECT3D:
Microsoft's 3D API. Includes all the function calls a developer needs to program old-style fixed-function games
as well as new programmable shader games.
DVI:
The connector used for digital LCD monitors; effectively eliminates the video noise from digital-to-analog-to-digital
conversion.
DVI-D:
A DVI hardware spec that only includes support for a digital signal. DVI-I cables will not fit into a DVI-D connector.
DVI-I:
A DVI hardware spec that allows both analog and digital signals to be passed out the DVI port.
FIXED-FUNCTION:
3D chips running fixed function 3D pipelines can execute a limited number of functions very rapidly. Unfortunately
fixed-functions pipelines are also inflexible, and developers can't easily use any functions that aren't built
into the chip. Programmable shader pipelines are replacing fixed-function pipelines.
FLOATING-POINT COLOR:
Floating-point numbers use decimals(e.g., 5.78) to describe a value. When games and applications use floating-point
numbers to describe color, rendering errors are minimized, and color become richer and more true to life. Videocards
with DirectX 9 support must be able to use high-precision, 128-bit floating-point numbers to describe colors.
Graphics processing unit—the main chip on a videocard. The GPU performs all the calculations that draw 3D images on your screen. GPUs include a rudimentary level of programmable shader support, whereas VPUs are totally programmable.
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HARDWARE TRANSFORM AND LIGHTING:
A graphics chip's hardware "T&L" engine can perform lighting calculations very quickly. Prior to
the introduction of hardware T&L, these calculations were performed by the already overloaded CPU.
HIGH-LEVEL SHADER LANGUAGE:
HLSL, the shader language that is included with DirectX 9. High-level shader languages allow game developers to
use a C-like programming language to write shader programs for gamers and graphic applications. Without an HLSL,
developers would have to use a confusing, hardware-specific assembly-level language.
Integer numbers have been used to describe color information since 3D graphics first appeared on the PC. Compared with floating-point number, integer numbers provide a very limited palette of colors. Integers are whole numbers (e.g., 4).
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MEMORY BANDWIDTH:
The amount of data that can be transferred between a graphics chip and its onboard memory. Measured in megabytes
per second(MB/s). To calculate memory bandwidth, multiply your memory bus bit-width by the speed of the memory
and the number of chunks of data transferred per clock, then divide that number by 8. For example: For 128-bit
DDR memory running at 500MHz, you would multiply 128 by 500 by 2, and then divide the product by 8. The result
is 16,0000MB/s, or 16GB/s.
MEMORY BUS WIDTH:
The size of each data chunk tat the memory bus can transfer each clock cycle. Usually measured in bits.
MIP-MAPPING:
Mip-mapping provides several different levels of detail for every texture in a scene, and places low-quality, low-res
textures in the background (where they're not easily noticed) and high-quality, high-res textures in the foreground(where
game players focus their attention). Because low-res textures consume relatively little memory, mip-mapping can
help speed up frame rates. Unfortunately, without filtering, demarcation lines can occur where different mip-map
levels intersect.
MULTI-SAMPLING:
An antialiasing technique that draws only the extra pixels needed to antialias jagged lines. Each GPU manufacturer
uses a different algorithm to perform a multi-sampling, so it's difficult to do an apples-to-apples comparison
with anti-liasing enabled. Multi-sampling is the preferred AA technique.
NV30:
The code-name for nVidia's first DirectX 9 GPU, which is the core for the GeForce FX line. It operates at speeds
up to 500MHZ, and is fabbed on a 0.13-micron process. The 5800 and 5800 Ultra use the NV30 core, while the 5200
series uses the NV34 core, and the 5600 series uses the NV31 core.
NV35:
nVidia's follow-up to the NV30. Fabbed on a 0.13-micron process, and the first nVidia chip to use a 256-bit memory
pipeline.
A 3D API designed by an independent standards body. OpenGL differs from DirectX mainly in its extensibility—it can be changes and added to between major revisions to take advantage of new hardware features.
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PCI EXPRESS:
The next-gen PCI replacement, slated to appear in late 2003 or early 2004. PCI Express will also replace the AGP
bus with PCI Express for Graphics, which should deliver 4GB/s of bandwidth to and from the 3D accelerator.
PIXEL SHADER:
A Programmable shader unit that manipulates individual pixels Pixel shaders can create bump maps, reflective surfaces,
and even programmatically generated textures.
PROCESS:
In respect to microprocessors, the term refers tot he size of transistors on a chip. Formerly measured in microns(one
millionth of a meter), but now measured in nanometers (one billionth of a meter). A smaller process technology
lets chips run at higher speeds and lower temperatures.
PROGRAMMABLE SHADER:
Programmable shader units are the areas of GPUs that can run generalized programs rather than fixed 3D functions.
There are two basic types of programmable shader units: pixel and vertex.
PROGRAMMATICALLY GENERATED TEXTURE:
Traditional textures in a 3D game are created in a bitmap editor, such as Photoshop, whereas programmatically generated
textures are described in real-time using shader programs. The newfangles textures do not require trilinear or
anisotropic filtering in order to maintain the proper perspective when they're applied to a 3D model.
R300:
The code-name for ATI's first DirectX 9 core. Fabbed on a 0.15-micron process, runs up to 325MHz, and supports
a 256-bit memory pipeline. The R300 is used in the Radeon 9500, 9500 Pro, 9700, 9700 Pro, and All-in-Wonder 9700
Pro.
R350:
ATI's follow-up to the R300. Fabbed on a 0.15-micron process, but operates at speeds up to 380MHz. The Radeon 9800,
9800 Pro, and All-in-Wonder 9800 Pro use the R350 core.
RAMDAC:
Random access memory digital to analog converter. The RAMDAC converts the digital signal that is output from your
3D card's frame buffer into an analog signal that your CRT monitor can understand, Your videocards's maximum resolution
and refresh rates are determined by RAMDAC strength.
RENDERMAN:
A high-level language for the complex shaders that are used in very detailed animated movies(such as shrek). Renderman
shaders use multiple computers working in tandem to draw a single frame. It's a very long and laborious process,
but 3D hardware companies hope to run Renderman-like shaders on consumer gaming hardware—at 60 frames per second—within
the next few years. Full Renderman shaders can run on DirectX 9 cards, but not at full speed.
SDRAM:
Synchronous dynamic random access memory. SDRAM is the dominant form of memory on today's videocards. Its low cost
and high speed make for a perfect combo. Variants of SDRAM (e.g., DDR SDRAM) run as high as 500MHz and provide
more than 20GB/s of memory bandwidth.
SUPER-SAMPLE:
An antialiasing technique. Super-sampling renders a scene at a high resolution, then filters it down tot eh desired
size, While this produces a terrific AA effect, its very slow, especially compared with multi-sampling. Super-sampling
isn't used on modern 3D accelerators.
TEXTURE COMPRESSION:
Most modern APIs include some from of texture compression. Because most textures are simply bitmaps, they're easily
compressed. This conserves the limited bandwidth between system memory and video memory, and between video memory
and the GPU, with virtually no degradation in image quality.
TRILINEAR FILTERING:
A texture filtering technique that blends pixels in different mipmaps to hide the seams between different mipmap
levels.
VERTEX SHADERS:
A programmable shader unit that specializes in geometry calculations. Vertex shaders handle terrain morphing, some
lighting calculations, and some shadow calculations.
VERTICAL SYNC:
A setting that allows you to synchronize the frame rate of your 3D accelerator's output to the refresh rate of
your monitor. Disabling vsync may allow your frame rate to go higher than your monitor's refresh rate, but at the
expense of nasty horizontal tears across the full-screen image.
VPU:
Visual processing unit. Some 3D companies designate their 3D chips as "VPUs." VPUs are fully programmable.
In fact, in theory you could perform any calculation on a VPU that would run on a CPU. On the other hand, GPUs
are capable of just a limited number of sequential operations.
VOLUMETRIC TEXTURE:
3D textures that can describe the rings of objects like tree rings. Volumetric textures consume significantly more
space—and thus memory bandwidth— than normal two-dimensional textures, but can be efficiently generated using pixel
shader programs.
The Z-buffer controls an object's distance from the camera in 3D rendered scene. It's also called the depth buffer. Low precision Z-buffers can make objects seem to pop, or clip, through each other.
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