Video CardsVideo Cards

CS431 Class PresentationCS431 Class Presentation

Ashish Bhat (02007025)Ashish Bhat (02007025)Nilesh Meshram (02007027)Nilesh Meshram (02007027)

IntroductionIntroduction

Interface between computer and a display Interface between computer and a display devicedevice

Unless a computer has graphics capability Unless a computer has graphics capability built into the motherboard, the video card is built into the motherboard, the video card is required. required.

The CPU, working in conjunction with The CPU, working in conjunction with software applications, sends information software applications, sends information about the image to the video card. The video about the image to the video card. The video card decides how to use the pixels on the card decides how to use the pixels on the screen to create the image. It then sends screen to create the image. It then sends that information to the monitor through that information to the monitor through output interface. output interface.

The Evolution of Video The Evolution of Video CardsCards

IBM introduced the first video card in 1981 IBM introduced the first video card in 1981 called a Monochrome Display Adapter (MDA), called a Monochrome Display Adapter (MDA), which provided text-only displays of green or which provided text-only displays of green or white text on a black screen. white text on a black screen.

Presently, the minimum standard for new Presently, the minimum standard for new video cards is Video Graphics Array (VGA), video cards is Video Graphics Array (VGA), which allows 256 colors. which allows 256 colors.

With high-performance standards like With high-performance standards like Quantum Extended Graphics Array (QXGA), Quantum Extended Graphics Array (QXGA), video cards can display millions of colors at video cards can display millions of colors at resolutions of up to 2040 x 1536 pixels. resolutions of up to 2040 x 1536 pixels.

Components in a Video Components in a Video CardCard

Graphics Controller / Graphic Graphics Controller / Graphic Processing Unit (GPU)Processing Unit (GPU)

Video Memory (RAM) Video Memory (RAM) Digital-to-analog Converter (DAC)Digital-to-analog Converter (DAC) Attribute ControllerAttribute Controller Output Interface - RGB, Composite, DVIOutput Interface - RGB, Composite, DVI BUS InterfaceBUS Interface BIOSBIOS

Components in a Video Components in a Video CardCard

Video Card - GPUVideo Card - GPU

Similar to CPU but designed Similar to CPU but designed specifically to perform complex specifically to perform complex mathematical and geometric mathematical and geometric calculations necessary for graphics calculations necessary for graphics renderingrendering

Less congestion on the system busLess congestion on the system bus Reduction in the workload of CPUReduction in the workload of CPU

Video Card - GPUVideo Card - GPU

Operations: bitmap transfers, painting, Operations: bitmap transfers, painting, window resizing and repositioning, line window resizing and repositioning, line drawing, font scaling and polygon drawing, font scaling and polygon drawing etc.drawing etc.

Some GPUs have image enhancement Some GPUs have image enhancement algorithms built-inalgorithms built-in– e.g. 3D edge smootheninge.g. 3D edge smoothening

Video Card - GPUVideo Card - GPU

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

Video Card - MemoryVideo Card - Memory

Video Memory (RAM) is used for:Video Memory (RAM) is used for:– Frame Buffering: holding completed Frame Buffering: holding completed

imaged until its time to display themimaged until its time to display them– As the GPU creates images, the image As the GPU creates images, the image

information is stored in this video memory information is stored in this video memory frame buffer as a digital bitmap frame buffer as a digital bitmap

– Total amount of video memory installed Total amount of video memory installed may not be needed for a particular may not be needed for a particular resolution, the extra memory often used resolution, the extra memory often used for caching information for the graphics for caching information for the graphics processor processor

for example, the caching of commonly for example, the caching of commonly used graphical items, such as text fonts used graphical items, such as text fonts and icons and icons

Unified memory architecture: Use of portion Unified memory architecture: Use of portion of system memory as frame buffer of system memory as frame buffer - Cost reduction - Cost reduction - Inferior graphics performance- Inferior graphics performance

The greater number of colors, or higher the The greater number of colors, or higher the resolution, the more video memory will be resolution, the more video memory will be required. required.

However, since it is a shared resource However, since it is a shared resource reducing one will allow an increase in the reducing one will allow an increase in the otherother

Video Card - MemoryVideo Card - Memory

Video Card - DACVideo Card - DAC

RAM connects directly to DACRAM connects directly to DAC– known as RAMDACknown as RAMDAC

Used to convert the digital image information Used to convert the digital image information stored in video memory into analog signals stored in video memory into analog signals that a monitor can usethat 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 - The rate at which the RAMDAC converts the information information - The design of the graphics processor - The design of the graphics processor

Multiple RAMDACMultiple RAMDAC

ResolutionResolution- specified in terms of a row by column figure - specified in terms of a row by column figure - the maximum number of displayable pixels - the maximum number of displayable pixels - determined by the beam size and dot pitch - determined by the beam size and dot pitch - refers to the sharpness, or detail of the visual image - refers to the sharpness, or detail of the visual image

Color DepthColor Depthdetermined by the intensity of three beams of light (Red, determined by the intensity of three beams of light (Red, Green and Blue) and the amount of information stored Green and Blue) and the amount of information stored about a pixelabout a pixel

Different ModesDifferent Modes8 Bit – 256 Color Mode 8 Bit – 256 Color Mode 16 Bit – High Color mode16 Bit – High Color mode24 Bit – True Color Mode 24 Bit – True Color Mode

Video Cards - Resolution and Video Cards - Resolution and Color depthColor depth

Video Card - Attribute Video Card - Attribute ControllerController

Contains the Color Look-up-Contains the Color Look-up-table (CLUT) which table (CLUT) which determines which color will determines which color will be displayed for a given be displayed for a given pixel value in the video pixel value in the video memorymemory

Used when the display mode Used when the display mode is not true color (24bit or is not true color (24bit or 48bit). In such cases the 48bit). In such cases the most used colors are stored most used colors are stored in this CLUTin this CLUT

Dithering Dithering - uses two colors to create - uses two colors to create the appearance of a thirdthe appearance of a third

- gives a smoother - gives a smoother appearance to abrupt appearance to abrupt transitions transitions

example color palette

Video Cards – Video Cards – Resolution and Colors Resolution and Colors

16.7 million1600x1200Ultra XGAUXGA

16.7 million1280x1024Super Extended Graphics Array

SXGA

16.7 million1024x768Extended Graphics Array XGA1990

16 from 262,144

256

640x480

320x200

Video Graphics

Array

VGA1987

16 from 64640x350 Enhanced Graphics

Adapter

EGA1984

None

16

640x200

160x200

Color Graphics

Adapter

CGA1981

No. of colorsResolutionDescriptionStandardDate

Output Interface - RGBOutput Interface - RGB

Most CRT monitors require signal in Most CRT monitors require signal in analog form. This interface is known analog form. This interface is known as RGB interfaceas RGB interface

This interface has three separate lines This interface has three separate lines for the red, green and blue color for the red, green and blue color signals, and two lines for horizontal signals, and two lines for horizontal and vertical sync signals and vertical sync signals

CRT controller in the video card CRT controller in the video card generates horizontal and vertical sync generates horizontal and vertical sync signalssignals

Output Interface - Output Interface - CompositeComposite

Composite video interface is used Composite video interface is used in Televisionin Television

First RGB data is converted into First RGB data is converted into chrominance (color) and chrominance (color) and luminescence (intensity) signals luminescence (intensity) signals and then both are time and then both are time multiplexed with horizontal and multiplexed with horizontal and vertical sync signals to give a vertical sync signals to give a single composite video signalsingle composite video signal

Output Interface - DVIOutput Interface - DVI

LCD Monitors work in LCD Monitors work in digital mode and digital mode and require display data in require display data in digital formdigital form

RAMDAC is thus RAMDAC is thus bypassed and data is bypassed and data is sent directly in digital sent directly in digital form. This interface is form. This interface is known as DVI (Digital known as DVI (Digital Video Interface)Video Interface) Output interface

requirement for different monitors

Video Card - BUS Video Card - BUS InterfaceInterface

ISA Interface (Obsolete)ISA Interface (Obsolete) PCI Interface (Obsolete)PCI Interface (Obsolete) AGP InterfaceAGP Interface PCI Express InterfacePCI Express Interface

AGP InterfaceAGP Interface

AGP = Accelerated Graphics PortAGP = Accelerated Graphics Port

Single dedicated Point-to-point Single dedicated Point-to-point ConnectConnect

Pipelined transfersPipelined transfers Video RAM SharingVideo RAM Sharing

Being replaced by new PCI ExpressBeing replaced by new PCI Express

Video Card - BIOSVideo Card - BIOS

Initialization of hardware setting Initialization of hardware setting during boot-upduring boot-up

Provides a set of standard Provides a set of standard routines to control and use the routines to control and use the video cardvideo card– e.g. change display mode, gotoxy, e.g. change display mode, gotoxy,

change color, write text etc.change color, write text etc.– traditionally video cards were built traditionally video cards were built

according to certain standards (CGA, VGA, according to certain standards (CGA, VGA, SVGA etc.) and provided the same SVGA etc.) and provided the same functionality through these standard functionality through these standard routines. routines.

Video Card InterfacingVideo Card Interfacing

Older video cards provide a set of Older video cards provide a set of standard routines accessed standard routines accessed through BIOSthrough BIOS

Display DriversDisplay Drivers

Video Card Interfacing Video Card Interfacing in Windowsin Windows

User Applications

OpenGL API DirectDraw APIWindows GDI

Display Driver OpenGL Driver DirectDraw Driver

Video Card

ReferencesReferences

http://www.howstuffworks.comhttp://www.howstuffworks.com http://www.pctechguide.com/http://www.pctechguide.com/ http://www.epanorama.nethttp://www.epanorama.net

Thank you!Thank you!

Video Card – Types of Video Card – Types of MemoryMemory

Standard DRAM – Used in earlier systemStandard DRAM – Used in earlier system Video memory implementation on Video memory implementation on

graphics boardgraphics board- VRAM- VRAM- WRAM- WRAM- EDO- EDO- SDRAM- SDRAM- DDRRAM- DDRRAM- RDRAM- RDRAM