EET Advanced Digital Display Adapters

A vital part to the system provides the visual part of the Human/Computer interface In boot process, goes through a variety of steps from mono-text through the highest color mode available Display unit must support the output

Board Types VGA boards - standard now Super VGA - follow VESA standards for high resolutions Graphic Accelerator - include 2D drawing instructions 3D accelerator board - includes 3D/rendering commands

Adapters Process - depends on commands from the CPU to display information –source of image may be from RAM, Disk, or created ‘on the fly’ –Accelerator chips provide hardware support for the ‘on the fly’ image generation –all other image forms are restricted by bus speed.

Technologies that affect speed –Chip-sets for accelerators –BUS technology –Register width of D/A card –Memory technology used VRAM –Designed to be accessed by both input and output devices at the same time

Video Memory SGRAM – Synchronous Graphics RAM –Not dual ported – used on moderate to high end cards WRAM – Window RAM –Faster & less expensive than VRAM –Supports full motion video 3-D RAM – designed to improve simulated three dimensional representations

–Resolution support 3 basic resolutions 640x480, 800x600, 1024x768 See Table 9-8 –Color support (mode) 24 bit or Mhues –Speed rating resolution vs frame rate –Bus bandwidth ISA – 16 bit, PCI - 32, AGP – 64 bit

Other Issues BIOS support OS support MMX Technology (3DNow) –Graphics accelerator in the CPU (Pentium)

Video Controllers CRTC – CRT Controller –Motorola 6845 – single chip control of traditional monochrome display. –Pages of text information, erase, scroll, etc. VGA Controller –Added control registers to allow complex control of detailed color images with greater color depth Cursor control –Included in hardware

RAM DAC Random Access Memory – Digital to Analog Converter –Provides analog control voltage for color control. Video information must be stored in MEMORY –Memory contents (text or graphic information) is converted to display

BIOS PC Video Bios –Original PC design provided CRT controls in BIOS VGA Bios –Extended BIOS controls to include color palettes & LCD control information Super VGA –VESA Bios extensions

Mode Numbers VESA Standard modes –See Table 16.5

Interfaces ISA VESA Local Bus UMA – Unified Memory Arch. VGA Auxiliary Video Connector –Card edge connector on VGA Board VESA feature Connector/ Advanced Feature Connector

Interfaces VESA Media Channel –Uses PCI Standard for video control features Advanced Graphics Port

Speed Comparison Each of the standard ports for Video Adapters are classified as ‘Local Bus’

FeatureVL-BusPCIAGP Speed132 MB/s 533M/1.06G Slots34/51 PnPNoYes CostInexpensiveHigherSim. to PCI Use486Pentium/P6PII/III etc StatusObsoleteCurrent

Other Video Issues TV Tuner Video Capture –NTSC –PAL –SECAM –HDTV

Troubleshooting Video Problems Power Light (LED) does not go on; No Picture –Check power –Check fuse –Check voltage select switch

Troubleshooting Video Problems Power LED is on; no picture –Check settings (contrast, etc) –Check Cable –Check System Configuration – hardware and software –Test Monitor on known good system –Reseat video card –Check socketed chips –Disable shadow video RAM

Troubleshooting Video Problems Power on, but monitor displays wrong characters. –Check Video card –Check motherboard

Troubleshooting Video Problems Monitor Flickers and/or has wavy lines –Check cable connection –Degauss –Check for nearby RF interference Fluorescent lights, speakers –Check settings for refresh rate

Troubleshooting Video Problems No graphics display or blank screen when loading certain programs –Check program requirements –Verify that card has necessary capabilities –Check adapter driver

Troubleshooting Video Problems –Other problems Screen goes blank after 30 seconds Poor quality color display Out of focus Other adjustments

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