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ISA Video card strange sparkly artifacts

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Divarin

Veteran Member
Joined
Mar 9, 2019
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565
Location
Cleveland, OH
Hi all, recently I posted about Recommendations on ISA SVGA card and I ended up buying an ET4000ax

The card I received works but I noticed that sometimes there's strange artifacts that appear usually at the top of the screen and usually while a scene is loading or unloading.

I looked around for similar issues or any similar screen shots and couldn't find any so I decided to just shoot a couple pics with my phone pointed at the monitor while running Future Crew's 2nd reality demo as these artifacts happen pretty consistently throughout that demo.

sparkles1.jpg



sparkles2.jpg



It seems that these sparkles come up while a scene is loading or unloading so I'm wondering if maybe it's bad ram on the video card and when certain locations of the ram are being written to that is causing it but I'm not sure about how that works and if that's possible.

The only thing I could think to try real quick was to try disabling video shadow ram in cmos but that had no effect.

Has anyone seen anything like this before?

It doesn't just happen in this demo it happens in some games as well.
 
Looking at the ram it looks like there are 4 chips:
2 HY534256S-70 (socketted)
2 MCM514256AP80 (non-socketted)

I also have two (seemingly compatible) ram chips on my OAK vga card:
2 MB81C4256A-60P (non-socketted)

so I could try desoldering the non-socketted chips and putting them in sockets then try replacing each chip one at a time with one of the chips from my oak card, assuming it won't take issue with having a 60ns chip mixed in with the 70 and 80 ns chips. Sounds like kind of a pain but not sure what else to try at the moment.

Is there maybe some program I can obtain (or write) that would let me test the vram while in use in the vga card?

Edit: I did try a couple of things.
I tried swapping the positions of the two socketted chips (thinking if one of those are bad then the issue might change, anomalies might appear on a different part of the screen or the system might lock up) but nothing changed.
I found something that's supposed to test vram (x-vesa) but when I run a test it seems to get stuck in the test forever. The screen is split up into 4 bands, the top 25% has some alternating colors, and each of the other quarters of the screen are solid colors (different colors)

I don't know if this means the ram is bad or the program doesn't work on my system, or I'm just supposed to wait forever for it to complete but the only way I can get out of the test is to ctrl+alt+del. I did try the supposedly fast test and it still seemed to just get stuck on that.
 
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Before you start desoldering chips I would try removing all non-essential ISA cards to rule out conflicts. Maybe also try different slots for the VGA.

I suppose it could be defective video memory. But in my experience that results in continuous on-screen garbage, even text modes.
 
I'd like to know what percentage of programs show this. If it is only a few I wouldn't bother doing any thing with the card just yet. Just because x86 hardware combinations were so diverse as was the software running on them
 
Plasma said:
Before you start desoldering chips I would try removing all non-essential ISA cards to rule out conflicts. Maybe also try different slots for the VGA.

I suppose it could be defective video memory. But in my experience that results in continuous on-screen garbage, even text modes.
Click to expand...
Okay I tried a different slot and removed non-essential cards but no difference. Although two cards are pretty much essential: IDE/floppy controller and NIC because I have an XT-IDE bios on the nic and without it my 2 gig HDD partition would be unreadable.

eswan said:
Not sure what bios options you have, but I'd check and see if the ISA bus is maybe running too fast.
Click to expand...
I'll have a look in my setup menu and see if there's anything related to bus speed that I can try changing.

Caluser2000 said:
I'd like to know what percentage of programs show this. If it is only a few I wouldn't bother doing any thing with the card just yet. Just because x86 hardware combinations were so diverse as was the software running on them
Click to expand...
That's a good point I think I'll take some time to just go through all of the games I have installed right now and record which ones have this issue and what video resolution it's running at the time.
 
looks like this issue happens in about half of the games I tried so far, almost always while a scene is fading in or out. However in simcity 2000 it's happening constantly throughout play but it's much more subtle, I didn't even notice it at first.
I mean it's probably something I could live with. strange thing is that I really haven't noticed any performance improvements over the crappy old OAK card I was using before. So far the only benefit is that I can get into simcity 2000 as it requires a vesa compliant card.
 
Could be, I did run the dazzle screen saver that does a lot of palette shifting and it didn't happen there but maybe it's in how the palette changes. Maybe tomorrow I'll try to shoot a video because I feel my explanations of what I'm seeing is not very good.
 
Divarin said:
strange thing is that I really haven't noticed any performance improvements over the crappy old OAK card I was using before.
Click to expand...

FWIW, one thing that *could* be a factor:

Divarin said:
NIC because I have an XT-IDE bios on the nic and without it my 2 gig HDD partition would be unreadable
Click to expand...

This is probably preventing your VGA card from running the BIOS in 16 bit mode because the requisite signal for that is qualified on 128k boundaries. The VGA BIOS is (almost always) 32k @C0000, and most AT bus motherboards don't let you put an option ROM above E0000, so unless your NIC has high/low sockets you're probably stuck with 8-bit ROM access because the NIC ROM is somewhere between C8000 and DFFFF.

I wouldn't think this would matter much for most games/graphical programs, though, only for the relatively rare case of programs using the BIOS text and (very limited) graphics routines; you should still be getting 16 bit VRAM access unless you are doing something like trying to run an MDA card at the same time.

If your computer has a BIOS option for VGA BIOS shadowing you might want to check it.
 
Eudimorphodon said:
FWIW, one thing that *could* be a factor:



This is probably preventing your VGA card from running the BIOS in 16 bit mode because the requisite signal for that is qualified on 128k boundaries. The VGA BIOS is (almost always) 32k @C0000, and most AT bus motherboards don't let you put an option ROM above E0000, so unless your NIC has high/low sockets you're probably stuck with 8-bit ROM access because the NIC ROM is somewhere between C8000 and DFFFF.

I wouldn't think this would matter much for most games/graphical programs, though, only for the relatively rare case of programs using the BIOS text and (very limited) graphics routines; you should still be getting 16 bit VRAM access unless you are doing something like trying to run an MDA card at the same time.

If your computer has a BIOS option for VGA BIOS shadowing you might want to check it.
Click to expand...

Interesting. No I don't have any other graphics cards installed (MDA or otherwise) I did try disabling Video shadowing (it was enabled by default) but it didn't have any effect on this issue so I re-enabled it.
I guess if I could think of a game that is a) small enough to fit on a floppy disk and b) has these graphical glitches then I could remove the NIC, boot off floppy, and see if these glitches are gone (and possibly if there's any improvement in performance) though off the top of my head I'm coming up empty thinking of a game/demo I could try.
Maybe I can go through scene.org's smaller demos.

Is there a way I can test if the video card is running in 16 bit mode or not?
 
Update: found a game that fits: hexxagon.
Put it on a floppy, removed the nic, booted off a different floppy then loaded up hexxagon.
Glitches are still there.
I don't know about performance as this game isn't very demanding.
 
Can you please post a high resolution picture of the card? I've recently come across an ET4k that had memory clock selectable by jumper
 
maxtherabbit said:
Can you please post a high resolution picture of the card? I've recently come across an ET4k that had memory clock selectable by jumper
Click to expand...

Sure, the only other jumper besides the 0ws jumper that I see is one labeled IRQ2, which is set to OFF.

s-l1600.jpg


This is actually the image from the ebay listing but I looked the card over and as far as I can tell the card I received is exactly like it minus the stray "1" sticker on the card edge. There are subtle differences like the label on one of my rom chips is slightly torn but the labels of the roms themselves match up.

I'm not exactly sure what would happen if I enabled the IRQ2 jumper, I guess I can try it and see.
 
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