Processor and Memory

Like a motherboard, a graphics card is a printed circuit board that houses a processor and RAM. It also has an input/output system (BIOS) chip, which stores the card's settings and performs diagnostics on the memory, input and output at start up. A graphics card's processor, called a graphics processing unit (GPU), is similar to a computer's CPU. A GPU, however, is designed specifically for performing the complex mathematical and geometric calculations that are necessary for graphics rendering. Some of the fastest GPUs have more transistors than the average CPU. A GPU produces a lot of heat, so it is usually located under a heat sink or a fan.

In addition to its processing power, a GPU uses special programming to help it analyze and use data. ATI and nVidia produce the vast majority of GPUs on the market, and both companies have developed their own enhancements for GPU performance. To improve image quality, the processors use:

• Full scene anti aliasing (FSAA), which smoothes the edges of 3-D objects
• Anisotropic filtering (AF), which makes images look crisper

­ Each company has also developed specific techniques to help the GPU apply colors, shading, textures and patterns.

The Evolution of Graphics Cards Graphics cards have come a long way since IBM introduced the first one in 1981. Called a Monochrome Display Adapter (MDA), the card provided text-only displays of green or white text on a black screen. Now, the minimum standard for new video cards is Video Graphics Array (VGA), which allows 256 colors. With high-performance standards like Quantum Extended Graphics Array (QXGA), video cards can display millions of colors at resolutions of up to 2040 x 1536 pixels.­

­ As the GPU creates images, it needs somewhere to hold information and completed pictures. It uses the card's RAM for this purpose, storing data about each pixel, its color and its location on the screen. Part of the RAM can also act as a frame buffer, meaning that it holds completed images until it is time to display them. Typically, video RAM operates at very high speeds and is dual ported, meaning that the system can read from it and write to it at the same time.

­ The RAM connects directly to the digital-to-analog converter, called the DAC. This converter, also called the RAMDAC, translates the image into an analog signal that the monitor can use. Some cards have multiple RAMDACs, which can improve performance and support more than one monitor. You can learn more about this process in How Analog and Digital Recording Works.

The RAMDAC sends the final picture to the monitor through a cable. We'll look at this connection and other interfaces in the next section.

How Graphics Cards Work

The images you see on your monitor are made of tiny dots called pixels. At most common resolution settings, a screen displays over a million pixels, and the computer has to decide what to do with every one in order to create an image. To do this, it needs a translator -- something to take binary data from the CPU and turn it into a picture you can see. Unless a computer has graphics capability built into the motherboard, that translation takes place on the graphics card.

A graphics card's job is complex, but its principles and components are easy to understand. In this article, we will look at the basic parts of a video card and what they do. We'll also examine the factors that work together to make a fast, efficient graphics card.

Think of a computer as a company with its own art department. When people in the company want a piece of artwork, they send a request to the art department. The art department decides how to create the image and then puts it on paper. The end result is that someone's idea becomes an actual, viewable picture.

A graphics card works along the same principles. The CPU, working in conjunction with software applications, sends information about the image to the graphics card. The graphics card decides how to use the pixels on the screen to create the image. It then sends that information to the monitor through a cable. ­

Creating an image out of binary data is a demanding process. To make a 3-D image, the graphics card first creates a wire frame out of straight lines. Then, it rasterizes the image (fills in the remaining pixels). It also adds lighting, texture and color. For fast-paced games, the computer has to go through this process about sixty times per second. Without a graphics card to perform the necessary calculations, the workload would be too much for the computer to handle.

GRAPHIC CARDS

Video or graphics circuitry, usually fitted to a card but sometimes found on the motherboard itself, is responsible for creating the picture displayed by a monitor. On early text-based PCs this was a fairly mundane task. However, the advent of graphical operating systems dramatically increased the amount of information needing to be displayed to levels where it was impractical for it to be handled by the main processor. The solution was to off-load the handling of all screen activity to a more intelligent generation of graphics card.

As the importance of multimedia and then 3D graphics has increased, the role of the graphics card has become ever more important and it has evolved into a highly efficient processing engine which can really be viewed as a highly specialized co-processor. By the late 1990s the rate of development in the graphics chip arena had reached levels unsurpassed in any other area of PC technology, with the major manufacturers such as 3dfx, ATI, Matrox, nVidia and S3 working to a barely believable six-month product life cycle! One of the consequences of this has been the consolidation of major chip vendors and graphics card manufacturers.

Chip maker 3dfx started the trend in 1998 with the its acquisition of board manufacturer STB systems. This gave 3dfx a more direct route to market with retail product and the ability to manufacture and distribute boards that bearing its own branding. Rival S3 followed suit in the summer of 1999 by buying Diamond Mulitmedia, thereby acquiring its graphics and sound card, modem and MP3 technologies. A matter of weeks later, 16-year veteran Number Nine announced its abandonment of the chip development side of its business in favour of board manufacturing.

The consequence of all this manoeuvring was to leave nVidia as the last of the major graphics chip vendors without its own manufacturing facility - and the inevitable speculation of a tie-up with close partner, Creative Labs. Whilst there'd been no developments on this front by mid-2000, nVidia's position had been significantly strengthened by S3's sale of its graphics business to VIA Technologies in April of that year. The move - which S3 portrayed as an important step in the transformation of the company from a graphics focused semiconductor supplier to a more broadly based Internet appliance company - left nVidia as sole remaining big player in the graphics chip business. In the event, it was not long before S3's move would be seen as a recognition of the inevitable.

In an earnings announcement at the end of 2000, 3dfx announced the transfer of all patents, patents pending, the Voodoo brand name and major assets to bitter rivals nVidia and recommended the dissolution of the company. In hindsight, it could be argued that 3dfx's acquisition of STB in 1998 had simply hastened the company's demise since it was at this point that many of its hitherto board manufacturer partners switched their allegiance to nVidia. At the same time nVidia sought to bring some stability to the graphics arena by making a commitment about future product cycles. They promised to release a new chip out every autumn, and a tweaked and optimized version of that chip each following spring. To date they've delivered on their promise - and deservedly retained their position of dominance!