What about the jumpers on the I/O card, have you tried a different configuration?

Could it be just marginally bad, so card's io decoding would overlap with other peripherals?
Another possibility if you have the compact flash adapter that grounds the ALE signal, this causes all kinds of addressing issues. It even might survive certain combinations of hardware, making you think the cause is not in CF but in something else.

dominusprog wrote on 2025-02-09, 15:00:

What about the jumpers on the I/O card, have you tried a different configuration?

I have not, but the BIOS is reporting the hard drive, floppy, serial and parallel controllers are all not present. And the floppy address cannot be changed.

I tried clearing the CMOS to no avail. I tried changing the video card back to 8 bit but it won't POST unless it's set to 16 bit.

vstrakh wrote on 2025-02-09, 15:01:

Could it be just marginally bad, so card's io decoding would overlap with other peripherals?

Always possible, but I'd hazard a guess that the 8900 contains that. This board does contain an odd arrangement of jumpers that makes me wonder about things like that. For example to switch to 16 bit mode, 6 jumpers need to be set and one of them is a set of 3 that the function of each is unclear.

vstrakh wrote on 2025-02-09, 15:01:

Another possibility if you have the compact flash adapter that grounds the ALE signal, this causes all kinds of addressing issues. It even might survive certain combinations of hardware, making you think the cause is not in CF but in something else.

I'm not using a CF card, but an IDE SSD through an adapter I made to keep the SSD from hogging the bus, something that CF cards also seem to like doing.

But maybe you're on to something! I was using a super-IO board based on a Holtek HT6550A that I have 2 of and have used in other configurations. It's always worked great, but I replaced it with a generic floppy/HDD controller I have with no serial/parallel and it works! So I have something to work off now.

eesz34 wrote on 2025-02-09, 16:37:

dominusprog wrote on 2025-02-09, 15:00:

What about the jumpers on the I/O card, have you tried a different configuration?

I have not, but the BIOS is reporting the hard drive, floppy, serial and parallel controllers are all not present. And the floppy address cannot be changed.

I tried clearing the CMOS to no avail. I tried changing the video card back to 8 bit but it won't POST unless it's set to 16 bit.

These I/O cards have jumpers for both IRQ and the address. Post a photo of the card.

dominusprog wrote on 2025-02-10, 13:37:

eesz34 wrote on 2025-02-09, 16:37:

dominusprog wrote on 2025-02-09, 15:00:

What about the jumpers on the I/O card, have you tried a different configuration?

I have not, but the BIOS is reporting the hard drive, floppy, serial and parallel controllers are all not present. And the floppy address cannot be changed.

I tried clearing the CMOS to no avail. I tried changing the video card back to 8 bit but it won't POST unless it's set to 16 bit.

These I/O cards have jumpers for both IRQ and the address. Post a photo of the card.

There are various configurations for parallel, serial, and hard drive interface. The floppy drive interface is either enabled or disabled, and that's it. When the Trident is used, everything present on this I/O card is missing. There's something weird about this VGA card because I've used this I/O card with Tseng and C&T ISA video cards without issue.

eesz34 wrote on 2025-02-09, 14:51:

Why would a video card conflict with I/O controllers?

It should not. Some mobos are very picky about which slot you put the video card in, but that's mostly older 286 mobos that lack termination for ISA slots. Post some photos of your mobo and card.

I have 8900D exactly like TRW photos except better build quality (axial caps instead of most ceramic discs and 0 ohm resistors instead of wire jumpers). Works without issues on 386 mobos I have but does not like older 286 mobos at all (black screen) - possibly due to issues with ALE. I seem to recall some CF card detection issues on another old mobo but can't quite recall the details now.

BTW you should have J1, J7 and J8 open, J3 as well if all RAM banks are populated, and J6 open, J9 all open, J10 closed. That's the correct config for 16-bit ISA bus. J2 (0WS jumper) is up to you, I have it closed for performance and didn't have issues except what I described above.

Deunan wrote on 2025-02-11, 14:17:

It should not. Some mobos are very picky about which slot you put the video card in, but that's mostly older 286 mobos that lack […]
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eesz34 wrote on 2025-02-09, 14:51:

Why would a video card conflict with I/O controllers?

It should not. Some mobos are very picky about which slot you put the video card in, but that's mostly older 286 mobos that lack termination for ISA slots. Post some photos of your mobo and card.

I have 8900D exactly like TRW photos except better build quality (axial caps instead of most ceramic discs and 0 ohm resistors instead of wire jumpers). Works without issues on 386 mobos I have but does not like older 286 mobos at all (black screen) - possibly due to issues with ALE. I seem to recall some CF card detection issues on another old mobo but can't quite recall the details now.

BTW you should have J1, J7 and J8 open, J3 as well if all RAM banks are populated, and J6 open, J9 all open, J10 closed. That's the correct config for 16-bit ISA bus. J2 (0WS jumper) is up to you, I have it closed for performance and didn't have issues except what I described above.

The MB has MR BIOS that is not original. I should probably try the original BIOS. I don't know how likely that is to cause this. By the way the MB photo is from when I first received it before I took the NiCd off, it's already long gone!

The video card photo is the seller's photo, and how I first tried it. The jumpers have been changed around multiple times.

I have in my notes that I tried those jumper settings, and attempted others as well but I will go back and try again. I tried setting to 8 bit mode but still black screen.

Ahh the joys hardware incompatibilities from the 80s and 90s. It's much easier to deal with when it's not your main computer.

For the 8-bit mode to work properly on this card it needs to be in 8-bit slot. If you try to force 8-bit but install it in 16-bit slot it might not work. Again I can't remember the details but that was my conclusion. Also it's sometimes better to force it than to let the card auto-detect but you can also try the jumper settings I gave you in the 8-bit slot. See if that does anything.

Your mobo is not of the "old" types that I mentioned, it should accept the card into any slot, but just to be sure try the first and last (closest to CPU and closest to mobo edge). BTW it would be best to use POST card to see what BIOS is doing, is the card really crashing the system completly or just fails to initialize. At least have the speaker connected for beep error codes.

Deunan wrote on 2025-02-11, 21:58:

For the 8-bit mode to work properly on this card it needs to be in 8-bit slot. If you try to force 8-bit but install it in 16-bit slot it might not work. Again I can't remember the details but that was my conclusion. Also it's sometimes better to force it than to let the card auto-detect but you can also try the jumper settings I gave you in the 8-bit slot. See if that does anything.

Your mobo is not of the "old" types that I mentioned, it should accept the card into any slot, but just to be sure try the first and last (closest to CPU and closest to mobo edge). BTW it would be best to use POST card to see what BIOS is doing, is the card really crashing the system completly or just fails to initialize. At least have the speaker connected for beep error codes.

I worked on this again and I think what was occurring was something really stupid. I noticed that when I plug the I/O card into the slot closest to the keyboard connector, where I've been using it, the bottom of the PCB hits the BIOS chip. This prevents full insertion into the slot. Things just worked out so it quit working with the Trident but worked with the ET4000. I have no other explanation. I played with the FIFO and WS jumpers and they didn't change anything obvious.

Ugh the lack of full standardization is what makes things frustrating, or interesting, I suppose.