Category : Printer + Display Graphics
Archive   : CSHOW873.ZIP
Filename : VIDEO.DOC

Video overview
--------------

CompuShow knows what "class" of video adapter (CGA, Hercules, EGA, MCGA, or
VGA) you have and therefore what graphics display modes are available. This
means that you DON'T NEED TO DO ANYTHING SPECIAL in order to display graphics
on ANY IBM COMPATIBLE graphics adapter.

However, there are two situations that CompuShow can't know about unless you
tell it; either that your video board has PROBLEMS with certain display modes,
or that it has ADDITIONAL display modes that go beyond the capabilities of a
"plain vanilla" board. For example, to get the most out of a Super-VGA, you'll
want to select the right video driver for it.

"Built-in" graphics modes
-------------------------

All "IBM standard" graphics displays, Hercules monochrome graphics, and two
non-standard 256-color modes (which work on the PS/2 and register-compatible
VGAs) are "built-in".

Mode (width x height x colors) Cga PCjr Ega MCGA VGA
+-+--------------------------------+---+----+---+----+---+
| |640x200 monochrome CGA | Y | | Y | | |
| |320x200x4 color (4 palettes) | Y | | Y | Y | Y |
|F|320x200x16 color PCjr | | J | | | |
|F|640x200x4 color PCjr | | J | | | |
| |320x200x16 color EGA | | | Y | | Y |
| |640x200x16 color EGA | | | Y | | Y |
| |640x350x16 color EGA | | | Y | | Y |
|F|640x480x16 color "Super-EGA" | | | S | | |
| |640x350 monochrome EGA | | | M | | |
| |640x480 monochrome MCGA/VGA | | | | Y | Y |
| |320x200x256 color MCGA/VGA | | | | Y | Y |
| |640x480x16 color VGA | | | | | Y |
+-+--------------------------------+---+----+---+----+---+
| |720x348 monochrome Hercules | | | | | |
|N|320x400x256 color non-standard | | | | P | P |
|N|360x480x256 color non-standard | | | | P | P |
+-+--------------------------------+---+----+---+----+---+
^
+-- N=oN unless turned off
F=oFf unless turned on
M=EGA with monochrome monitor
J=PCjr (Tandy-1000) graphics
S="Super-EGA"
P=PS/2 and register compatible VGAs

Enabling/Disabling built-in modes
---------------------------------

The command-line switches described under "Start-up options" in SETUP.DOC
enable or disable these built-in modes and features:

The non-standard 320x400x256 and 360x480x256 modes work on the PS/2 and all
hardware-compatible VGAs, giving a "plain vanilla" VGA something approaching


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Super-VGA quality. However, laptops in particular (perhaps some others) may
not be able to do one (or both) of these modes.

Some (early non-IBM) EGA adapters could not do hardware panning. If your EGA
graphics display is "scrambled", turn this off.

The program can set the color palette in MCGA/VGA 16 and 256 color modes
either through the video BIOS or by programming the hardware directly. You may
find that one technique is smoother (or quicker) than the other (check it by
rotating the palette).

If you have a "Super-EGA", with a 640x480x16 mode, your owner's manual should
indicate the "mode number" (you'll need to enter the DECIMAL mode number).

PCjr graphics modes (320x200x16 and 640x200x4) are also available on a number
of Tandy 1000 models. Enabling these modes reserves 32k of memory, so this
option is found under "Memory options (and PCjr/Tandy graphics)".

Extended Graphics Modes
-----------------------

In addition to the built-in display modes, CompuShow supports a wide-range of
extended graphics adapters by means of over thirty special video drivers
(which are listed, below).

In CompuShow, F1help then "S" executes the SETUP program. It has two
selections to help if you're not sure which driver you need. "Attempt to
identify Super-VGA chipset" tests the installed VGA adapter and presents a
list of possible matches. If the list includes "VESA", that's probably the
best choice for your computer. "Peek at VGA BIOS area" may show a
manufacturer's name.

Of course, if your adapter doesn't go beyond the standard modes, then you
DON'T NEED a video driver. Drivers are listed alphabetically in four groups:

Modern Super-VGAs
Older Super-VGAs
Modern non-SVGAs
Early video adapters

____Modern Super-VGA adapters_______________________________

A modern Super-VGA should have VESA BIOS Extensions (VBE). The Video
Electronics Standards Association (VESA) is an industry organization and every
major video board manufacturer belongs. They've established a standard so that
software developers no longer have to 'scramble' to keep up with dozens of
different ways of programming Super-VGA adapters from different manufacturers.
The VBE are in the Video BIOS ROM chip on most high quality Super-VGA boards.
(Some of the lower quality boards may require you to load the VBE as a TSR
program, although hopefully this practice is dying out.)

Our VESA video driver supports all 20 VESA Super-VGA graphics modes, in 16,
256, 32k, 64k, and 16m colors and resolutions ranging from 640x400 through
1280x1024. (CompuShow is limited to 15 video driver modes. While we have yet
to find a board with over 15 VESA modes, a special selection routine is used
to pick the 15 "best" modes in the VBE.)


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In the early days of VESA, some board manufacturers failed to support all the
graphics display modes in their VBE. If your board's VBE doesn't support the
modes that it should, contact the manufacturer for an upgrade. If you're
having trouble with a Diamond (SpeedStar, Stealth, Viper, etc), see the note
at the end of this document.

VESA BIOS Extensions
800x600x16 1024x768x16 1280x1024x16 640x400x256 640x480x256 800x600x256
1024x768x256 1280x1024x256 640x480x32k 800x600x32k 1024x768x32k 1280x1024x32k
640x480x64k 800x600x64k 1024x768x64k 1280x1024x64k 640x480x16m 800x600x16m

1024x768x16m 1280x1024x16m

____Older Super-VGA adapters________________________________

AcuMos
800x600x16 1024x768x16 640x400x256 640x480x256 800x600x256

Ahead Systems
800x600x16 1024x768x16 640x400x256 640x480x256 800x600x256 1024x768x256

ATI VGAs
800x600x16 1024x768x16 640x400x256 640x480x256 800x600x256 1024x768x256
640x480x32k

Chips & Technologies
800x600x16 640x400x256 640x480x256 800x600x256

Compaq QVision
640x480x256 1024x768x256 640x480x32k 512x480x16m 640x400x16m

Diamond Speedstar 24 (not "24X")
640x400x256 640x480x256 800x600x256 1024x768x256 640x480x32k 800x600x32k
640x480x16m

Everex VGAs
800x600x16 1024x768x16 640x400x256 640x480x256 800x600x256 1024x768x256

Genoa 6400 GVGA
800x600x16 1024x768x16 512x512x256 640x350x256 640x400x256 640x480x256
800x600x256

NCR
800x600x16 1024x768x16 640x400x256 640x480x256 800x600x256 1024x768x256

Oak Technologies
800x600x16 1024x768x16 640x480x256 800x600x256 1024x768x256

Early Oak VGAs had a serious BIOS bug (which was apparently corrected in later
models). Attempting to use a video mode which wasn't available on a particular
model would prevent the board from doing graphics again until the computer was
re-booted. So if you find a mode that doesn't work (and disable it), you may
have to re-boot the computer before you can use the other graphics modes.

Paradise/WestrnDigtl
800x600x16 1024x768x16 640x400x256 640x480x256 800x600x256



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STB EM16+
800x600x16 1024x768x16 640x400x256 640x480x256 800x600x256 1024x768x256

STB Ergo+Sierra DAC
640x400x256 640x480x256 800x600x256 1024x768x256 320x200x32k 640x480x32k
800x600x32k

Trident VGA
800x600x16 1024x768x16 640x400x256 640x480x256 800x600x256 1024x768x256

Tseng 3000
800x600x16 1024x768x16 640x350x256 640x480x256 800x600x256

Tseng 4000
800x600x16 1024x768x16 640x400x256 640x480x256 800x600x256 1024x768x256

Tseng4000+Sierra DAC
640x400x256 640x480x256 800x600x256 1024x768x256 640x400x32k 640x480x32k
800x600x32k

Video 7
800x600x16 1024x768x16 640x400x256 640x480x256 800x600x256 1024x768x256

____Modern non-SVGAs________________________________________

DGIS
[Available modes depend on the video adapter and DGIS interface]

Hercules GraphxStatn
640x400x256 640x480x256 800x600x256 1024x768x256 1024x768x256 640x480x32k
512x480x16m
[The first 1024x768x256 is interlaced, the second is non-interlaced]

IBM XGA
1024x768x16 640x480x256 1024x768x256 640x480x64k

IBM 8514/A
640x480x16 1024x768x16 640x480x256 1024x768x256
[Load the "adapter interface" (HDILOAD) in AUTOEXEC.BAT]

TIGA
[Available modes depend on the video adapter and TIGA interface]

____Early video adapters____________________________________

Amstrad PC1512
640x200x16

ATI Graphics Solution (plantronics)
320x200x16 640x200x16

AT&T 6300
640x400x2 640x400x16

AT&T DEB
640x400x16


[VIDEO.DOC] Page 4
Cirrus
640x400x16 720x540x16 800x600x16

Hercules InColor
720x348x16

IBM CGA
160x100x16

IBM PGC
640x480x256

Plantronics
320x200x16

Tandy 1000SL/TL
640x200x16

Problems with Diamond VGAs
--------------------------

Unfortunately, we've had literally dozens (perhaps hundreds?) of calls and
messages from people having trouble getting a Diamond VESA BIOS to work. For
months, the Diamond tech support area on CompuServe has been "buzzing" with
angry messages from frustrated Diamond customers!

As of this writing (1/94) we've been contacted by Diamond tech support, and it
sounds like they're FINALLY looking into their VESA BIOS bugs. While there's
no way of knowing how long it may take them to fix the problems, it does
appear that they're now working on them, so PLEASE CONTACT THE DIAMOND TECH
SUPPORT people to see if they have a fix for your model.

In the meantime, since Diamond's VESA BIOSes have had so many bugs, a couple
of ShareWare replacements have proven to be the only answer for some Diamond
models. One is specifically for the Diamond "Viper" model. It can be found as
VPRVS*.ZIP in CompuServe's IBM hardware forum (GO IBMHW) in library 3. The
other is a "universal" VESA BIOS (which supports 15-20 Super-VGA chipsets). It
can be found as UVBE*.ZIP in the IBMPRO forum, library 12. We'll have a copy
of each (which may not be as up-to-date as CompuServe) on the GraF/X BBS (602-
282-9035).


















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