Video Display Adapter Timelines and Hardware Standards
Video graphics display adapter standards, timelines and connector pin outs.A board that plugs into a personal computer to give it display capability.
| Video Adapter Timeline | ||||||||
| Year: | Model: | By: | Max Pixels: | Colors: | Palette: | Type: | Refresh rate | |
| 1981 | MDA | Mono Display Adapter | IBM | 720x350 | 2 | 2 | TTL | 50 Hz |
| 1981 | CGA | Color Graphics Adapter | IBM | 160x200 | 4 | 16 | TTL | 60 Hz |
| 1981 | RGBI | Red Green Blue Intensity | IBM | 640x200 | 4 | 16 | TTL | 60 Hz |
| 1982 | HERC | Hercules Display Adapter | IBM | 720x348 | 2 | 2 | TTL | 50 Hz |
| 1984 | PGA | Professional Graphics Array | IBM | 640x480 | Analog | |||
| 1984 | EGA | Enhanced Graphics Adapter | IBM | 640x350 | 16 | 65536 | TTL | 60 Hz |
| 1987 | 8514/A | Video Standard for PCs | IBM | 1024x768 | 256 | 262,000 | Analog | 43.5 Hz |
| 1987 | MCGA | MultiColor Graphics Array | IBM | 720x400 | 256 | Analog | 60Hz | |
| 1987 | VGA | Video Graphics Array | IBM | 320x200 | 256 | 262144 | Analog | 70Hz |
| 1988 | VGA | Video Graphics Array | VESA | 1600x1200 | DDC | 85Hz | ||
| 1990 | XGA | eXtended Graphics Array | IBM | 1024x768 | 16 | 256 | DDC | 70 Hz |
| 1990 | SVGA | Super VGA | VESA | 1600x1200 | 256 | DDC | Analog | 60 Hz |
| 1991 | EVGA | Extended VGA | VESA | 1024x768 | 256 | DDC | Analog | 70 Hz |
| Never run your monitor out of spec. If your display is screwed up, there's a good chance that the frequencies are out, so turn off the monitor! | ||||||||
DB-9  Video Connector Pinouts | |||||||
| Pins | MDA | CGA | EGA | ECL | PGA | VGA | RGB |
| Pin 1 | Ground | Ground | Ground | ECL Video | Red | Ground | Red |
| Pin 2 | Ground | Ground | Red Intensity | ECL Video Return | Green | Ground | Green |
| Pin 3 | Not Used | Red | Red | Horizontal Sync | Blue | Red | Blue |
| Pin 4 | Not Used | Green | Green | Vertical Sync | Composite Sync | Green | Video Sync |
| Pin 5 | Not Used | Blue | Blue | +5v | Mode Control | Blue | +5v |
| Pin 6 | Intensity | Green Intensity | Green Intensity | ECL Video | Red Ground | Ground | Right Audio |
| Pin 7 | Mono Video | Blue Intensity | Blue Intensity | ECL Video Return | Green Ground | Not Used | Left Audio |
| Pin 8 | Horizontal Sync | Horizontal Sync | Horizontal Sync | Sync Return | Blue Ground | Horizontal Sync | Luma (Y) |
| Pin 9 | Vertical Sync | Vertical Sync | Vertical Sync | +5v Return | Ground | Vertical Sync | Chroma (C) |
DB-15  Video Connector Pinouts | ||||
| XGA | VGA | VESA VGA | ||
| Pin 1 | Red | Red | Red | |
| Pin 2 | Green | Green | Green | |
| Pin 3 | Blue | Blue | Blue | |
| Pin 4 | ID Bit | ID Bit | ID Bit | |
| Pin 5 | Self Test | N/C | N/C | |
| Pin 6 | Red Return | Red Return | Red Return | |
| Pin 7 | Green Return | Green Return | Green Return | |
| Pin 8 | Blue Return | Blue Return | Blue Return | |
| Pin 9 | No Pin | No Pin | No Pin | |
| Pin 10 | Ground | Ground | Ground | |
| Pin 11 | ID Bit | ID Bit | ID Bit | |
| Pin 12 | ID Bit | ID Bit | ID Bit | |
| Pin 13 | Horizontal Sync | Horizontal Sync | Horizontal Sync | |
| Pin 14 | Vertical Sync | Vertical Sync | Vertical Sync | |
| Pin 15 | ID Bit | ID Bit | ID Bit | |
| Recommended Monitor Size | |
| 640x480 | 13" |
| 800x600 | 15" |
| 1024x768 | 17" |
| 1152x864 | 19" |
| 1280x1024 | 21" |
| Monitor Size Viewing Area | |
| 12" | 10.5" |
| 14" | 12.5" |
| 15" | 13.5" |
| 16" | 14.5" |
| 17" | 15.5" |
| 18" | 16.5" |
| 19" | 17.5" |
| 20" | 18.5" |
| 21" | 19.5" |
| Standard Color Depth | |
| 32 bit | 16,777,216 (True Colors + Alpha Channel) |
| 24 bit | 16,777,216 (True Colors, SVGA) |
| 16 bit | 65,536 (High Color, XGA) |
| 8 bit | 256 colors (VGA) |
| 4 bit | 16 colors (EGA) |
| 2 bit | 4 colors (CGA) |
| 1 bit | 2 colors (monochrome) |
| Glossary | |
| Analog | The traditional method of modulating radio signals so that they can carry information. Amplitude modulation (AM) and frequency modulation (FM) are the two most common methods of analog modulation. Today, most U.S. cellular systems carry phone conversations using analog; the transition to digital transmissions is happening slowly. |
| DDC | Display Data Channel, a VESA standard for communication between a monitor and a video adapter. Using DDC, a monitor can inform the video card about its properties, such as maximum resolution and color depth. The video card can then use this information to ensure that the user is presented with valid options for configuring the display. |
| dpi | dots per inch, which indicates the resolution of images. The more dots per inch, the higher the resolution. A common resolution for laser printers is 600 dots per inch. This means 600 dots across and 600 dots down, so there are 360,000 dots per square inch. |
| ISA | Industry Standard Architecture, is the bus design that has been used in most PCs since IBM released the PC/AT more than a decade ago. It's a limited 8-bit and 16-bit bus, but it's so widely compatible that it has outlasted technologically superior and much faster bus standards like PCI. |
| PCI | Peripheral Component Interconnect, a self-configuring PC local bus called PCI. Designed by Intel, PCI has gained wide acceptance (even by Apple, in its PowerPC series). It beats out the VESA Local Bus spec from a technical standpoint and will presumably win out in the long run. The bottom line: if you have a Pentium, make sure any add-in board you buy is a PCI device. |
| Pixel | A pixel on a monitor is a number of red, green, and blue phosphor dots. These dots are "excited" to varying degrees by the monitor's three electron guns, and the results mix additively to generate a specific color. By manipulating large numbers of pixels in precise ways, patterns emerge to make up an identifiable picture. |
| Refresh rate | The image on your computer monitor doesn't just appear fully formed on the screen's phosphors: it's drawn line by line with beams fired from three electron guns at the back of the CRT. (The three guns are for different colors--red, green, and blue. The colors blend to build all the colors you see.) The frequency at which they redraw the image is called the refresh rate, and it's an important measure of how steady the image will appear. |
| Resolution | A monitor's resolution refers to the number of pixels in the whole image, because the number of dots per inch varies depending on the screen's dimensions. For example, a resolution of 1,280 by 1,024 means that 1,024 lines are drawn from the top to the bottom of the screen, and each of these lines is made up of 1,280 separate pixels--and in turn, each dot may have any number of combinations of red, green, and blue intensities. |
| RGB | RGB refers to the so-called scientific hues--the additive primary colors red, green, and blue--that, when mixed together in equal amounts, create white light. Television sets and computer monitors display their pixels based on values of red, green, and blue. |
| TTL | Transistor-Transistor Logic, a common type of digital circuit in which the output is derived from two transistors. The first semiconductors using TTL were developed by Texas Instruments in 1965. The term is commonly used to describe any system based on digital circuitry, as in TTL monitor. |
| Video Adapter | A board that plugs into a personal computer to give it display capabilities. The display capabilities of a computer, however, depend on both the logical circuitry (provided in the video adapter) and the display monitor. A monochrome monitor, for example, cannot display colors no matter how powerful the video adapter. |
| VESA | This industry organization formed to create various personal computer standards, including those for Super VGA video displays and the VLB bus standard. |
| VLB | VESA Local Bus, This 32-bit, far speedier improvement over the IBM PC's 8-bit and 16-bit ISA bus architecture gained popularity with the advent of Intel's 80486 processor. However, VLB has been superceded recently with the introduction of the Pentium and Intel's superior PCI bus. |
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Created 9:52 AM 1/9/01
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Copyright © 2001 Eric A. Arnold
Last Modified on: 10:47 PM 12/7/01