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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
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