Summary of Video Standards

• Hercules, MDA
• CGA Colour Graphics Adapter
• EGA Enhanced Graphics Adapter
• ECL, Sun and Apollo Monochrome
• VGA

EGA Enhanced Graphics Adapter

Video Type: TTL, 16/64 colours

This stands between CGA and VGA cards. It was introduced in 1984 and continued until 1987, when the first IBM PS/2 systems were introduced. It could produce 64 colours but display only 16 of them at one time when used with an EGA monitor. It had a high resolution mode and a monochrome mode and was compatible with all previous monitors, including CGA and monochrome.

EGA Pin Out

640 x 350, 15.7/21Khz, 60Hz

	Pin	Description
	1	Ground
	2	Red Intensity
	3	Red
	4	Green
	5	Blue
	6	Green Intensity
	7	Blue Intensity
	8	Horizontal Sync
	9	Vertical Sync

ECL, Sun and Apollo Monochrome

EGA Pin Out

640 x 350, 15.7/21Khz, 60Hz

	Pin	Description
	1	ECL Video
	2	ECL Video return
	3	Horizontal Sync
	4	Vertical Sync
	5	5 volts
	6	ECL Video
	7	ECL Video return
	8	Sync return
	9	5V return

Apple, Mac II/Quadra
640x480 to 1152x870
35-68kHz, 66.7-70Hz

Use of analogue video signals allows for unlimited colours to be produced. Macintosh graphic cards are unique in a couple of different regards. First, the variety of sync formats. In the past, sync has been available three different ways, and in some cases all from on card. Those formats are RGsB, RGBS, and RGBHV. Macintosh graphic cars also offer multiple lines rates and resolutions. These rates are resolutions are determined at boot up by the manner in which the sense lines (ID Bits) are terminated within the local monitor. Signal Type: Analogue

	Pin	Description
	1	Red Ground
	2	Red
	3	Composite Sync
	4	Sense 0
	5	Green
	6	Green Ground
	7	Sense 1
	8	N/C
	9	Blue
	10	Sense 2
	11	C/V Ground
	12	Vertical Sync
	13	Blue Ground
	14	Horizontal Ground
	15	Horizontal Sync

IBM, XGA, XGA-2, Super VGA
Extended Graphics Array
640x480 to 1600x1200

31.5 - 117kHz, 40 - 110Hz. IBM developed XGA/XGA-2 to provide a means to offer higher frequencies and resolutions in the "VGA" domain. These standards utilise software and ID bit termination to achieve these changes.

Custom XVGA, Up to 1600x1200 31-117kHz, 60-110Hz
Note: Many graphic card manufacturers offer super high resolution modes that are not necessarily a standard, like XGA or VESA. Thus, a customer running on of these standard modes can be displaying a graphics resolution up to 1600x1200 at 117kHz, horizontal.

VGA
640x480 31.5kHz, 60/70Hz

IBM developed VGA in 1987, as one of the first computer video types to use analogue signals. The ability to display sharper images with high colour depth is something that, even today, is being constantly expanded upon. The most commonly recognised resolution is 640x480, 31.5kHz with 16 displayable colours out of a colour palette of 64. Super VGA and XGA offer many more rates and resolutions.

VESA VGA (DDC)
VGA=Video Graphics Adapter or Video Graphics Array.
VESA=Video Electronics Standards Association.
DDC=Display Data Channel.
640x480 to 1600x1200
31.5-106kHz, 56-85Hz

This standards committee was adopted in 1988 to create a better standard than IBM VTGA version. So far, VESA has offered more variety in video resolutions and it is still adopting more standards each year. Signals type: analogue To date, VESA has adopted standards that range from standard VGA (at 640x480) to super high resolution graphics (1600x1200 at 106kHz). Most VESA graphics cards are capable of switching resolutions "on-the-fly" if you are using Windows 95.

VESA Super VGA

In an attempt to bring some order to the chaos of competing and incompatible Super VGA standards on the market, the Video Electronics Standards Association (VESA) has worked to establish new video interface standards. The intention of these standards is to once again provide a standardised application program interface between video hardware and application software. This would allow software developers to write their code to work with a single standard video model instead of having to write custom code to support the many different cards in use in the market today. Originally ignored by many vendors, VESA support is now becoming generally accepted as beneficial, and something that buyers look for when shopping for a video card. This is in part due to the growing number of programs (especially games) that require VESA SVGA compatibility in order to function at peak performance. The VESA SVGA standard is called the VESA BIOS Extension, sometimes abbreviated as VBE. There are actually more than one now, as more than one version of the standard exists. What is interesting about VBE is that it can be implemented in either hardware or software. Some video cards support a particular VBE standard in hardware. Those that do not can use a small memory-resident program, which is sometimes called a "VESA driver" even though it technically is not a driver--that will provide VESA support for many cards that do not support VBE natively. This flexibility has helped encourage the widespread adoption of the standard because even proprietary hardware can be made to work with standard software, mostly transparently. There are two common VBE standards currently in use: version 1.2 and version 2.0. Obviously, version 1.2 is seen much more in hardware than version 2.0 because it is older. Many newer cards provide native VBE 2.0 support. For those that do not, there are memory-resident programs such as SciTech Display Doctor that can be used to provide VBE 2.0 support. For older cards, a program such as Display Doctor can actually improve performance because it controls the hardware more efficiently than the onboard BIOS does. Hardware support for VBE version 2.0 is preferable as this avoids the necessity of using a software program to provide VESA support. However, there are reports of some cards that have buggy implementations of VBE 2.0 that do not always work 100% correctly. In these cases supplementing with something like UniVBE can eliminate some of these problems.

VESA Feature Connector 26 Pin Idc at the Video card.

13W3 IBM PowerPC
640x480 to 1600x1200
31 - 61 kHz, 60 - 87Hz

Some versions of the IBM PowerPC computer come equipped with a 13W3 video connector. This connector is utilised to maintain the signal integrity at the high frequencies at which this computer is capable of operating.

13W3 Sun Colour
1152x900
61 - 89 kHz, 60 - 80Hz

Sun manufactures high end computers that are capable of very high resolutions. They are able to output these various resolutions from the same card, this is determined at boot up by the manner in which sense lines (ID Bits) are terminated within the local monitor.

Monitor Sense Bits Defined:

13W3 SGI (Silicon Graphics)
1024 x 768 & 1280x1024
30-82kHz, 60-76Hz

Silicon Graphics manufacturers high end computers that are sued in graphic rendering and CAD/CAM applications. This computer generally operated at two different frequencies (48kHz and 64kHz), which is determined upon boot up. This computer type outputs sync RsGsBs, RGsB, RGVS and RGBHV.

13W3 NeXT Colour
1152x870
63.9kHz, 60Hz

This computer type utilises the 13W3 video connector to display high resolution graphics. The video output generally operates at 63kHz an is designed to work in conjunction with its local monitor.

13W3 Intergraph

* Used only with 2 MPIXEL Monitors
(GT + Graphics Engine MSMT081)

PGA

In 1984, IBM introduced the Professional Graphics Array, or PGA. The name gives away its intended audience. This system, priced at almost $5,000, was intended for serious scientific or engineering applications. With a built on 8088 processor, it could perform 3D manipulation and animation at up to 60 frames per second. Besides the price, this system took up a total of three motherboard slots. Obviously, the cost precluded this system from ever taking on to the general public, and was later dropped for the VGA adapter.

VGA, 9 Pin
VGA = Video Graphics Adapter or Video Graphics Array.

8514/A

8514/A is a standard produced by IBM to work with its MCA bus. It works well, producing high resolutions on interlaced monitors. A later adaptation allowed fast refresh rates on noninterlaced monitors, producing high quality flicker free images. 8514/A works quite differently than a VGA, although they both use the same kind of monitor. On a 8514/A, the computer tells the video card what to do and the video card figures out how to do it. For example, it says "Draw a circle" and the card figures it out. These are higher level commands and are quite different than the pixel by pixel instructions which must be calculated by the CPU in standard VGA cards. This is called hardware acceleration.
8514/A cards are much faster than VGA cards and often provide higher quality images than the VGA card. Nevertheless, IBM discontinued this format in favour of the more advanced XGA.

MCGA

The multicolour Graphics Array is archaic hardware. It was integrated into the motherboards of old PS/2 models 25 and 30. When coupled with a proper IBM display, it supported all CGA modes, but it was not compatible with previous monitors. MCGA could muster 64 shades or grey, thereby giving it the ability to simulate colour images on monochrome monitors.