Video Cards CS431 Class Presentation Ashish Bhat ( ) Nilesh Meshram ( )

Introduction Interface between computer and a display device Interface between computer and a display device Unless a computer has graphics capability built into the motherboard, the video card is required. Unless a computer has graphics capability built into the motherboard, the video card is required. The CPU, working in conjunction with software applications, sends information about the image to the video card. The video card decides how to use the pixels on the screen to create the image. It then sends that information to the monitor through output interface. The CPU, working in conjunction with software applications, sends information about the image to the video card. The video card decides how to use the pixels on the screen to create the image. It then sends that information to the monitor through output interface.

The Evolution of Video Cards IBM introduced the first video card in 1981 called a Monochrome Display Adapter (MDA), which provided text-only displays of green or white text on a black screen. IBM introduced the first video card in 1981 called a Monochrome Display Adapter (MDA), which provided text-only displays of green or white text on a black screen. Presently, the minimum standard for new video cards is Video Graphics Array (VGA), which allows 256 colors. Presently, 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. 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.

Components in a Video Card Graphics Controller / Graphic Processing Unit (GPU) Graphics Controller / Graphic Processing Unit (GPU) Video Memory (RAM) Video Memory (RAM) Digital-to-analog Converter (DAC) Digital-to-analog Converter (DAC) Attribute Controller Attribute Controller Output Interface - RGB, Composite, DVI Output Interface - RGB, Composite, DVI BUS Interface BUS Interface BIOS BIOS

Components in a Video Card

Video Card - GPU Similar to CPU but designed specifically to perform complex mathematical and geometric calculations necessary for graphics rendering Similar to CPU but designed specifically to perform complex mathematical and geometric calculations necessary for graphics rendering Less congestion on the system bus Less congestion on the system bus Reduction in the workload of CPU Reduction in the workload of CPU

Video Card - GPU Operations: bitmap transfers, painting, window resizing and repositioning, line drawing, font scaling and polygon drawing etc. Operations: bitmap transfers, painting, window resizing and repositioning, line drawing, font scaling and polygon drawing etc. Some GPUs have image enhancement algorithms built-in Some GPUs have image enhancement algorithms built-in –e.g. 3D edge smoothening

Video Card - GPU Some of the latest GPUs have more transistors than average CPU and produce a lot of heat. Heat-sinking and fan cooling are required Some of the latest GPUs have more transistors than average CPU and produce a lot of heat. Heat-sinking and fan cooling are required

Video Card - Memory Video Memory (RAM) is used for: Video Memory (RAM) is used for: –Frame Buffering: holding completed imaged until its time to display them –As the GPU creates images, the image information is stored in this video memory frame buffer as a digital bitmap –Total amount of video memory installed may not be needed for a particular resolution, the extra memory often used for caching information for the graphics processor for example, the caching of commonly used graphical items, such as text fonts and icons for example, the caching of commonly used graphical items, such as text fonts and icons

Unified memory architecture: Use of portion of system memory as frame buffer Unified memory architecture: Use of portion of system memory as frame buffer - Cost reduction - Inferior graphics performance The greater number of colors, or higher the resolution, the more video memory will be required. The greater number of colors, or higher the resolution, the more video memory will be required. However, since it is a shared resource reducing one will allow an increase in the other However, since it is a shared resource reducing one will allow an increase in the other Video Card - Memory

Video Card - DAC RAM connects directly to DAC RAM connects directly to DAC –known as RAMDAC Used to convert the digital image information stored in video memory into analog signals that a monitor can use Used to convert the digital image information stored in video memory into analog signals that a monitor can use The range of refresh rates decided by: The range of refresh rates decided by: - The rate at which the RAMDAC converts the information - The design of the graphics processor Multiple RAMDAC Multiple RAMDAC

Resolution Resolution - specified in terms of a row by column figure - the maximum number of displayable pixels - determined by the beam size and dot pitch - refers to the sharpness, or detail of the visual image Color Depth Color Depth determined by the intensity of three beams of light (Red, Green and Blue) and the amount of information stored about a pixel Different Modes Different Modes 8 Bit – 256 Color Mode 16 Bit – High Color mode 24 Bit – True Color Mode Video Cards - Resolution and Color depth

Video Card - Attribute Controller Contains the Color Look-up-table (CLUT) which determines which color will be displayed for a given pixel value in the video memory Contains the Color Look-up-table (CLUT) which determines which color will be displayed for a given pixel value in the video memory Used when the display mode is not true color (24bit or 48bit). In such cases the most used colors are stored in this CLUT Used when the display mode is not true color (24bit or 48bit). In such cases the most used colors are stored in this CLUT Dithering Dithering - uses two colors to create the appearance of a third - gives a smoother appearance to abrupt transitions - gives a smoother appearance to abrupt transitions example color palette

Video Cards – Resolution and Colors 16.7 million1600x1200Ultra XGAUXGA 16.7 million1280x1024Super Extended Graphics Array SXGA 16.7 million1024x768Extended Graphics ArrayXGA from 262, x x200 Video Graphics Array VGA from 64640x350Enhanced Graphics Adapter EGA1984 None x x200 Color Graphics Adapter CGA1981 No. of colorsResolutionDescriptionStandardDat e

Output Interface - RGB Most CRT monitors require signal in analog form. This interface is known as RGB interface Most CRT monitors require signal in analog form. This interface is known as RGB interface This interface has three separate lines for the red, green and blue color signals, and two lines for horizontal and vertical sync signals This interface has three separate lines for the red, green and blue color signals, and two lines for horizontal and vertical sync signals CRT controller in the video card generates horizontal and vertical sync signals CRT controller in the video card generates horizontal and vertical sync signals

Output Interface - Composite Composite video interface is used in Television Composite video interface is used in Television First RGB data is converted into chrominance (color) and luminescence (intensity) signals and then both are time multiplexed with horizontal and vertical sync signals to give a single composite video signal First RGB data is converted into chrominance (color) and luminescence (intensity) signals and then both are time multiplexed with horizontal and vertical sync signals to give a single composite video signal

Output Interface - DVI LCD Monitors work in digital mode and require display data in digital form LCD Monitors work in digital mode and require display data in digital form RAMDAC is thus bypassed and data is sent directly in digital form. This interface is known as DVI (Digital Video Interface) RAMDAC is thus bypassed and data is sent directly in digital form. This interface is known as DVI (Digital Video Interface) Output interface requirement for different monitors

Video Card - BUS Interface ISA Interface (Obsolete) ISA Interface (Obsolete) PCI Interface (Obsolete) PCI Interface (Obsolete) AGP Interface AGP Interface PCI Express Interface PCI Express Interface

AGP Interface AGP = Accelerated Graphics Port AGP = Accelerated Graphics Port Single dedicated Point-to-point Connect Single dedicated Point-to-point Connect Pipelined transfers Pipelined transfers Video RAM Sharing Video RAM Sharing Being replaced by new PCI Express Being replaced by new PCI Express

Video Card - BIOS Initialization of hardware setting during boot-up Initialization of hardware setting during boot-up Provides a set of standard routines to control and use the video card Provides a set of standard routines to control and use the video card –e.g. change display mode, gotoxy, change color, write text etc. –traditionally video cards were built according to certain standards (CGA, VGA, SVGA etc.) and provided the same functionality through these standard routines.

Video Card Interfacing Older video cards provide a set of standard routines accessed through BIOS Older video cards provide a set of standard routines accessed through BIOS Display Drivers Display Drivers

Video Card Interfacing in Windows User Applications OpenGL APIDirectDraw APIWindows GDI Display DriverOpenGL DriverDirectDraw Driver Video Card

References

Thank you!

Video Card – Types of Memory Standard DRAM – Used in earlier system Standard DRAM – Used in earlier system Video memory implementation on graphics board Video memory implementation on graphics board - VRAM - WRAM - EDO - SDRAM - DDRRAM - RDRAM