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First post, by thothie

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My old BFG 6800GTOC AGP supported CGA in old dos applications at the command line. I have a few small, old, but critical aps that I need from time to time that use these graphics modes.

My new EVGA 7950GTKO gives me this error:

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16 bit MS-DOS Subsystem
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Command Prompt - portalinv
The NTVDM CPU has encountered an illegal instruction.
CS:c000 IP:d6fc OP:c6 7c 00 00 00 Choose 'Close' to terminate the application.
---------------------------
Close Ignore
---------------------------

I'm wondering - did the nVidia PCI-E line stop supporting DOS/CGA? I read elsewhere of a person with a 7800 who can get basic graphics in DOS - but I'm not sure if he's PCI-E or AGP.

Before you bring up DOSBOX, sadly neither of these programs will run under DOSBOX emulator software, so that's not an option in this case. (Although at least I can play Magic Carpet with that. 😎 )

Any and all DOS based graphics mode generate this blank screen of death and error. I actually went into my old copy of Qbasic and activated each mode, one at a time.

==================================================
As per the forum rules:
The following are things that should be in your help request:
* Motherboard: Intel DG965WH
* Processor type and speed: Conroe e6300
* Amount and type of RAM: 1GB DDR2
* Video board w/ RAM amount and type: EVGA nVidia 7950GT KO 512MB DDR3
* Sound board: Audigy2 ZS Platinum
* Operating system: Windows XP SP2
* Game name (and version, if applicable): All Dos Graphics
* Description of problem (be detailed: saying "it's jerky" doesn't help, saying "the player sprites seem to be jerky when I'm pressing any of the arrow keys" does): See Above
* Reproducibility of problem (always, only once, always but only on a specific level, etc.): Always
* Sound mode used: N/A
* Video mode (Software, OpenGL, Direct3D, or Glide, and resolution): Software/Any
* Steps already attempted to solve the problem: Virus/Spyware checks, Driver Clean + Reinstall, Clean Windows XP Reinstall

Reply 1 of 30, by eL_PuSHeR

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Hello, thothie. WELCOME TO THE FORUM.

Yes, modern nVIDIA cards (and probably all the rest too) are known to have dropped some backwards compatibility. That's one of the reasons why I prefer ATi these days (VESA support still working under WinXP).

How did you configure DOSBox for using those programs? Did you set machine=cga for them?

Could you tell us the name of these programs. Maybe the developers can do a quick test for you.

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Reply 3 of 30, by thothie

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Well, it's old custom inventory software, so I suspect I'd have to give it to them.

I'd think that it was that the graphics card simply doesn't support the format anymore, like you say - but I was talking to a guy on Guru 3D who was able to get CGA in DOS on a BFG nVidia 7800 - I'd downgrade my card one gen for that ability. I'm tempted to take the thing back due to other shortcomings as it is (EVGA=Crap).

Anyone here have a PCI-E Nvidia GeForce 7XXX card that runs CGA?

If it works right, this should turn your screen white (any key to exit):
http://www.thothie.com/4jiggly5/cga_test.zip
(If it don't, alt-tab and exit)

I'd just like to make sure the card I replace it with can handle it natively.

Reply 4 of 30, by eL_PuSHeR

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The test you posted works fine for me both under NTVDM and DOSBox 0.65 (machine=vga). I have got an ATi card (X800GTO AGP).

What videocard drivers are you using? Tried different driversets?

Intel i7 5960X
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Reply 6 of 30, by thothie

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Great, I've been nVidia for so many years, I've learned all the painful ins and outs, and I'm going to have to buy an ATI now? 😦 I did have a brief and painful experience with an ATI 9800XT years ago, I dropped it for an FX5600, so that should give you some idea of how bad the experience was. 😉

I've actually tried it with the raw-VGA drivers, and it gives the same error.

I've not tried older Forceware drivers, but I figure if the raw VGA gets the same error...

Wish I knew where I could go to get reliable info on which cards do and do not support this... Again, 3DGuru guy says he has it going on a BFG7800 - but again, don't know if his is AGP or PCI, and he's vanished.

Reply 7 of 30, by wd

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What happens when you set some cga mode? (especially try the cga graphics
modes and see if it stays in text mode or just screws up the screen).

What's exactly wrong with running it under dosbox?

Reply 8 of 30, by wd

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Any and all DOS based graphics mode generate this blank screen of death and error. I actually went into my old copy of Qbasic and activated each mode, one at a time.

Um so ANY modeset through int10 causes this crash?? Even mode12 and mode13?

Reply 10 of 30, by thothie

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What happens when you set some cga mode? (especially try the cga graphics
modes and see if it stays in text mode or just screws up the screen).

Goes blank for sec, then gives me that error pop-up I described in the first post. If I click ignore, the screen stays blank until I force it to close.

What's exactly wrong with running it under dosbox?

Just goes smashie, no error, no log - although DOSBOX can run that CGA test I sent out - if I am forced to do this through DOSBOX I'll setup a post on the subject in that forum. I'll get a new graphics card before I go that far though. Frankly, I'm not willing to tolerate lack of basic functions on my $300+ graphics card, when the $300+ from three years ago ran it just fine. I mean, what's next - no software mode support?

I'd really like to stick to a GeForce 7xxxx card if I can though, if I can find someone with one who can run CGA, I'll buy their brand.

Um so ANY modeset through int10 causes this crash?? Even mode12 and mode13?

Yeah, even 12 and 13, oddly enough (aren't those text modes!?). Screen 0 works fine.

"mode con: cols=80 lines=25" gives me a mode that looks like screen 13, as does the diagnostic screen I get when it boots up. "mode con:cols=40" doesn't get me the classic 40 col PCjr text mode, but I don't think it ever did in XP.

What happens under real ms-dos? Could you test some modes?

I got some servers running underneath me at the moment, but as soon as it's clear I'll stick in a boot disk and see what happens.

The graphics card isn't the only thing I've updated though... The CPU, Mobo, and Memory are all new as well (hence the need for a new graphics card - I was quite happy with my BFG6800GT.) It seems the most likely culprit though. My mobo has graphics as well (although I'm sure it's insufficient), I'll give that a shot and see what happens as well.

Reply 11 of 30, by wd

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Hex modes 12/13 are standard vga modes, so they *should* work
(640x480x16col and 320x200x256col).
Either something is bugged in the vga bios (it would not work then
under raw dos as well), or it's some funny incompatibility with the OS
(if it works under dos). Not sure how much effect drivers can have on
int10. But in all cases you could try debugging the int10 handler,
yet that might be more trouble than it's worth.

For dosbox: try the debugger-enabled build, it gives by times interesting
information. Also try to play with the ems/xms settings in dosbox.conf,
and use loadfix before starting the prog.

Reply 12 of 30, by thothie

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THE MYSTERY THICKENS

Alright... I booted onto a floppy with Qbasic... Guess what, on the pure-dos floppy, IT WORKS. So it's not that the modes aren't there, it's just it won't use them at the Windows command line without going smashie.

The on-board Intel Graphics card DOES work in DOS and the Windows Command Line, just fine. So it IS the EVGA 7950GT graphics card at fault here...

Sadly, this brings me no closer to a solution.

EVGA tech support has still not responded. I could call BFGtech, but I know their level 2 techs aren't in on the weekends. Come Monday I'll have to seriously look into returning the card.

I'd hate to turn this card in, only find another brand with the same issue.

So far I've not verified that anyone with a PCI-E card can get CGA graphics at the command line.

Reply 13 of 30, by eL_PuSHeR

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Hey hold on for a second...

You say you are using an integrated Intel graphic card under ms-dos. Have you disabled onboard video in bios? We need to test the EVGA under ms-dos, not the onboard one. Or you could try taking the EVGA out of the machine and test those modes under Windows but using onboard video.

Intel i7 5960X
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8 GB DDR4 (2100)
8 GB GeForce GTX 1070 G1 Gaming (Gigabyte)

Reply 14 of 30, by thothie

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No, I'm saying I tested both ways.

The EVGA card works in pure DOS, but not in Windows.

The integrated card works in both.

Ergo, the EVGA card sux. (It's not the fault of the CPU, mobo, memory, or something else.)

And yes, disabled through the BIOS (actually no other way to switch between the cards on this board, can't have both active at the same time.)

Reply 15 of 30, by eL_PuSHeR

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Thanks. So it seems the EVGA is the culprit here. Bad backwards compatibility I guess. But it's weird that neither mode 12h nor 13h won't work.

Intel i7 5960X
Gigabye GA-X99-Gaming 5
8 GB DDR4 (2100)
8 GB GeForce GTX 1070 G1 Gaming (Gigabyte)

Reply 16 of 30, by thothie

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My *guess* is (or rather, I should say, my *fear* is) that the NTVDM CPU's virtual int10 can't translate to PCI-E cards, so any attempt to change the screen mode from the command prompt fails, even if it's valid or pure text.

Again, I've not found anyone with a PCI-E card who can tell me if the CGA test works or not.

Reply 17 of 30, by eL_PuSHeR

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I don't think that is the case. 😒

Problem must lie somewhere else.

By the way... Can you do the following?

1. Make a backup copy of both AUTOEXEC.NT, CONFIG.NT that are located at the \WINDOWS\SYSTEM32 folder.

2. Replace them with copies found at \WINDOWS\REPAIR

3. Reboot and see if that makes any difference.

Intel i7 5960X
Gigabye GA-X99-Gaming 5
8 GB DDR4 (2100)
8 GB GeForce GTX 1070 G1 Gaming (Gigabyte)

Reply 18 of 30, by thothie

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Did that. :\

Also did SFC /scannow.

Also, mind you, did fresh XP install.

Basically, until I find someone with a PCI-E card that can do CGA, I think I'm SOL.

In some chinese forum on the subject I managed to extract this related VDD registry path:
HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Control/VirtualDeviceDrivers [ key: VDD type: Reg_Multi_Sz Data: (empty) ]

I notice if I fux with that, I can make it crash different, but at the same function (ie. change graphics mode, it yells at me about invalid VDD instead of the above error). I'm wondering if there's some way to point the VDD to my graphic driver, or... Somethin... (shot in the dark to say the least.)

Reply 19 of 30, by tannerstevo

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The cga test works with my ati x1900 crossfire card, both in single and crossfire mode, but my card has some other issues with older games (tomb raider most notably). So I would say that all manufacturers are dropping some backwards compatibilty.