OS/2 SVGA NETINFO

By Bernie Thompson
 * Revision 1.0
 * April 8, 1992

INTRODUCTION
This little document is meant to shed some light on how OS/2 can utilize SVGA hardware. I'll start out with a description of all of the files involved, their duties, and where they live; and I'll have a question and answer session with myself (schitzoid, but hopefully informative).

\OS2\SVGADATA.PMI
This file serves as a flag to tell OS/2 whether SVGA support has been enabled with SVGA ON. The file actually contains data on

1. What video chipset your SVGA card has.

2. What SVGA modes, from the supported list, your adapter is capable of setting. The list of supported modes is:
 * a. 640x480/256
 * b. 800x600/16
 * c. 800x600/256
 * d. 1024x768/16
 * e. 1024x768/256
 * f. 132x25 text
 * g. 132x43 or 44 text

3. What values are in the video registers when the card is in each mode. this data is used by OS/2 to save and restore the registers to their proper state when switching between sessions with different SVGA modes set.

This data file must be generated by typing SVGA ON from a DOS FULLSCREEN, because what SVGA ON actually does is set all the possible modes using the video card's BIOS and then read out the values of the registers into the .PMI file. If SVGA ON is run from a DOS window, OS/2's video virtualization takes over, and the BIOS doesn't set the svga modes properly.

\OS2\SVGA.EXE
This is the utility that generates the .PMI file and places it in the \OS2 subdirectory. Syntax is SVGA (ON)(OFF)(STATUS), where
 * ON: creates the \OS2\SVGADATA.PMI file and enables SVGA support.
 * OFF: deletes the .PMI file.
 * STATUS: returns the chipset type OS/2 thinks your card is.

\OS2\DLL\DISPLAY.DLL
This file determines what video resolution the PM desktop uses.

This is the PM display driver and the heart of OS/2 video. The equivalent file on a Windows system is the VGA.DRV (in the case of VGA) file. For the first release, SVGA systems will have a VGA display driver installed on their system. Already, SVGA drivers are available from most of the main board manufacturers. In this document, I'll try to list some of the ones that are working.

\OS2\DLL\BVHSVGA.DLL
This file is the Base Video Handler for OS/2. Any OS/2 application that sets a video mode calls this DLL. In mode cases, however, the only application that sets any video modes is the PM display driver and the MODE.EXE utility (for setting 132 column modes). The first time this DLL would be called is after the OS/2 bitmap logo appears (PM starts up then). This DLL is specified in the CONFIG.SYS in the following manner: SET VIO_VGA=DEVICE(BVHVGA,BVHSVGA) BVHVGA is used to set, save, and restore VGA modes, BVHSVGA for SVGA modes.

\OS2\MDOS\VSVGA.SYS
This is the virtual video device handler for DOS sessions. All calls to change the video mode from a DOS session are handled through this driver. This driver's job is to allow the user to set a SVGA mode, and when the user switches away, save the current state of the video card (its registers and its video RAM). Then, when the user returns to the DOS session, restore the video card to it's previous state. When there is no .PMI file (SVGA is OFF) this driver acts like a VGA driver, except for adapter-specific code in it to make sure the VGA modes work right on the SVGA adapter. Therefore, even if you don't want SVGA, you'll probably want VSVGA.

\OS2\MDOS\WINOS2\SYSTEM\VGA.DRV & \OS2\MDOS\WINOS2\SYSTEM\SWINVGA.DRV
These are the WINOS2 and seamless WINOS2 drivers, respectively. They determine what resolution WINSO2 uses.

QUESTION AND ANSWER
Q: I'm having problems with my video.

A: Start by reading the README in your root directory.

Q: I'm having problems with my video.

A: In many cases, OS/2 requires a different dip switch setup for your adapter. Try some of the suggested variations in your adapter manual.

Q: I have an adapter that uses the Tseng ET4000 chipset. My video goes out of sync when entering a DOS or WinOS2 fullscreen, what's the deal?

A: Tseng ET4000 chips with a batch # TC6059AF or higher will exhibit this effect. Through talking to Tseng, we have developed a solution, and hopefully by the time you read this your problem will be gone.

Q: What SVGA support is actually provided with OS/2 2.0 GA edition?

A: The only support that is provided in the shrink wrapped version is the ability to switch away from a DOS or OS/2 fullscreen and have the current state of your video card saved.. and this is only after you have turned SVGA ON, and if you have one of the adapters listed in the readme..although everyone with a Tseng, Trident, ATI, Headland, or Western Digital chipset should try turning SVGA ON at least for a while to see if it fixes any unseemly video problems they might be having.

Q: For what adapters has DOS + OS/2 fullscreen save/restore been tested?

A:
 * ATI VGA Wonder XL
 * Boca Reseach SVGA
 * Orchid Prodesigner II
 * STB Powergraph
 * Trident 8900C and 8900B
 * Video 7 VRAM II
 * Paradise VGA Professional

Q: Are these the only cards which are "compatable" with OS/2?

A: NO. Our support is designed to be generic for the Trident, Tseng, ATI, Headland, and Western Digital chipsets. There are likely many more cards which work under OS/2 which we havn't even tried. If you have a card which isn't on this list, but does work, please send a note to the email address at the bottom of this document with the name of the card and any small limitations you found.

Q: How do I get my PM desktop to use SVGA?

A: OS/2 does not provide any PM SVGA drivers.. they are available from the board manufracturers. At this time, there are drivers from Trident, Orchid, ATI, Tseng, Paradise, and probably countless others. Check around for more updated lists than this.

Q: Will my W*nd*ws 3.0 drivers work in WinOS2?

A: Yes, you should be able to simply update the SYSTEM.INI to point to a new windows display driver, or just copy over VGA.DRV in the OS2\MDOS\WINOS2\SYSTEM directory. Keep in mind, however, that Windows in SVGA will only work if you have SVGA ON.

Q: Why do I have to deal with this SVGA ON and OFF crap?

A: Because we've torn out many clumps of hair discovering all of the crazy things that can happen when you try to provide video support for for so many different boards, each with their own quirks. Most importantly, we found that turning SVGA ON actually caused some system's video to become worse.. so we had to have a way to give the user the ability to switch back and forth. And so was born the SVGA ON OFF thing. Hopefully a more elegant system will be developed in the future.

Q: I have an ATI 8514 Ultra.. does it work under OS/2?

A: Yessir. Because of it's 8514 compatability, this is a keen card. If your Ultra is hooked into an SVGA card, you will probably have to change the line in your CONFIG.SYS that reads: DEVICE=\OS2\MDOS\VVGA.SYS to: DEVICE=\OS2\MDOS\VSVGA.SYS

This will make OS/2 alot more friendly towards your Ultra's little brother.

Other than the complication of which card the Ultra is hooked into, OS/2 treats it just like a 8514 card. Contact ATI for any special problems with this card.

Q: I'm getting some corruption returning to my WinOS2 fullscreen

A: Set your VIDEO_SWITCH_NOTIFICATION in the DOS SETTINGS to ON.

Q: Even in VGA, games in a DOS fullscreen are shakey

A: Set your VIDEO_RETRACE_EMULATION in the DOS SETTINGS to OFF.

Q: Alot of DOS apps in a window have messed up colors

A: This is a limitation of the VGA desktop. The color palatte of the DOS session has to be translated to PM, and the 640x480/16 desktop doesn't offer enough colors to do a good translation. The only solution to the problem is to use a 256 color PM driver.

Q: My friend has the same video card as me, and it doesn't work.. can't I just give him a working SVGADATA.PMI file?

A: No. The SVGADATA.PMI has to be specific to each adapter/monitor setup.

Q: If I have SVGA ON, can I use 132 column modes in an OS/2 fullscreen?

A: yep.

Q: If I have SVGA ON, can I window a DOS fullscreen onto the PM desktop, even if it is Super VGA?

A: yep!

Q: If I have SVGA ON, can I take a window with a SVGA image in it can paste to the clipboard?

A: YEP!

Q: Hey, wait a minute. A month ago in 304e, there was no SVGA support at all!

A: Yep! Long hours, buddy, long hours.

Q: Who were the guys who did all the work on OS/2 SVGA support?

A: Dale Whitfield and Bill Boden. They aren't on the net, but still give them a hand for the cool stuff that's here and still to come.

Bernie Thompson PSU student and IBM co-op

I don't know if this will eventually end up in his hands, but I'd like to thank Timothy F. Sipples, Keeper of the OS/2 Frequently Asked Questions, for all of his work over the last couple months. OS/2 owes you one.

DISCLAIMER
The opinions and suggestions contained herein are my own and not those of my employer. This document does not represent any sort of guarantee or assurance. Just tips guys... nothing legal, get it? Good.