EET 450 - Advanced Digital

Display Adapters

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 32 - 16.7 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’

Feature VL-Bus PCI AGP

Speed 132 MB/s 132MB/s 533M/1.06G

Slots 3 4/5 1

PnP No Yes Yes

Cost Inexpensive Higher Sim. to PCI

Use 486 Pentium/P6 PII/III etc

Status Obsolete Current Current

Other Video Issues

• TV Tuner

• Video Capture– NTSC– PAL– SECAM– HDTV

Assignment

• Review ‘Flat Panel Displays’

• Write 1-2 page ‘summary’ of information found - include periodicals – SEE WEB PAGE