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CRT Terminator Digital VGA Feature Card ISA DV1000

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Reply 180 of 193, by clb

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Also now I see that the message about latching behavior that SNOOP.EXE reports is wrong and can be ignored (this was a bug in SNOOP that I have fixed, but I notice I didn't uploaded a fixed version of SNOOP to GitHub)

The palette snow message is likely related to the palanim flashing.

When you write that "palanim [...] looks perfectly smooth from the VGA out.", do you mean that the palette animation effect also correctly cycles when viewed on VGA? Or does VGA show static unmoving image?

Reply 181 of 193, by CircuitRewind

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clb wrote on 2025-02-01, 10:16:

That sounds unexpected/something that I feel like I haven't seen before. Would you be able to record a video of what that looks like?

https://youtu.be/FDsmeTsNm9s

My guess is that since the Terminator thinks its getting corrupt palette information, Entry 0 (or which ever is the entry for the background color) is being "updated" incorrectly, causing the flashing. The colors of the bars themselves are also often wrong, looking rainbowish.

Reply 182 of 193, by clb

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Thanks for the video. Something is definitely off here.

It does look like CRT Terminator is thinking that palette index 0 is getting programmed with something non-black (likely a result of some corruption/confusion). The PALANIM.EXE test program explicitly writes color 0=(0,0,0) at every loop iteration, so something unexpected is happening.

I added a new PALTEST.EXE program for unit testing palette upload behavior. Would you be able to give that program a go and see what it prints? Hopefully there might be able to give some clues to what is the source of the problem.

The PALTSR program should NOT be running when PALTEST.EXE is run. (it would confuse the test)

Reply 183 of 193, by CircuitRewind

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clb wrote on 2025-02-03, 20:28:

I added a new PALTEST.EXE program for unit testing palette upload behavior. Would you be able to give that program a go and see what it prints? Hopefully there might be able to give some clues to what is the source of the problem.

Thanks for the fast response! 😀

I've attached the output from the command, and yeah, its totally not happy all over the place. This is from a fresh-boot straight into DOS with a nearly empty autoexec.bat/config.sys

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Reply 184 of 193, by clb

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Ouch, yeah, the results are quite unexpected.

I presume if you run that multiple times, the printout will be randomly different with fluctuating fail rates and actual fail numbers that it prints?

This is starting to paint some kind of picture. There is definitely a problem with interfacing the ISA bus in general, and not just with the palette read/writes.

I updated PALTEST.EXE with a couple of new tests to probe a bit more information about the issue. Can you give this updated version a go?

https://github.com/juj/crt_terminator/commit/ … 5cbd9989d219205

Hopefully that will tell us a bit more about where the root cause of the ISA interface problems could lie.

Reply 185 of 193, by clb

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One more thing I notice is that you are on Windows 95. As a sanity check it might be good to try out real-mode DOS 6.22 to make sure there aren't any wholly unexpected things at play with Win95. (not sure what those could be, it should work there as well, just I haven't actually tested Windows 95 or newer with CRT Terminator, just on Windows 3.11)

Reply 186 of 193, by CircuitRewind

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clb wrote on 2025-02-04, 13:23:

I updated PALTEST.EXE with a couple of new tests to probe a bit more information about the issue. Can you give this updated version a go?

1) For testing, I've been booting straight into DOS, bypassing Windows loading. I've only been using my Windows CF card because it has easy network access to download new test files. 😀

2) The color issues persist even in the BIOS before the OS even loads. The palettes are entirely arbitrarily random. I've gotten a few times now where the initial bootup was black text on a black background through the Terminator, while of course will perfectly fine on the normal VGA output.

3) And yes, the errors seen while running the text are entirely random and different each time it is ran. Running it over and over again without rebooting or running anything else, and the error list changes.

4) Terminator has been tested in 3 separate ISA slots, all the same behavior. Card wont reach the 4th slot.

5) Other cards in the ISA slots work just fine, including the 3Com network card, Adaptec SCSI card, and SoundBlaster card.

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Reply 187 of 193, by clb

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Thanks for all the details, and the patience to persist to debug.

In the screenshot, I now see that the result from the first tests actually scroll outside the screen and are not visible in the screenshot. Were there any tests that would have showed a PASS, or did all the tests fail, even those that scrolled off the screen?

One hypothesis here is an ISA I/O address conflict with another device on the ISA bus. CRT Terminator uses ISA I/O address range 120h-12Fh.

If you haven't already, try removing any other ISA cards to see if that would affect the issue.

Also if there might exist any BIOS settings that might affect ISA bus communication, could be useful to try.

Another hypothesis is some kind of a timing issue with ISA bus reads or writes. The test [Test ISA bus Read no intr] in the beginning of the run might be able to help diagnose this.

Reply 188 of 193, by CircuitRewind

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Okay, this setup is getting super duper weird.

I disabled the onboard IDE controller and pulled all ISA cards from the machine.

Doing so, no more palette errors.... but even worse, no more palette reading -at- -all-

Putting in ANY ISA card into any slot, regardless of card (sound, modem, SCSI, NIC) would allow the Terminator to see palette updates again, but often corrupt.

But I noticed, despite some tests "passing" with all the cards removed, info from the Terminator card seems bokt? Just look at the reported version number from it!

I've also been testing with and without the paltsr just in case, but that changes very little.

Also, just now while uploading these pics, I realized that the two runs of "snoop" show wildly different model numbers for the card at the top.

The card looks like it gets stuck sometimes reporting 0xE8 for all responses. 0xE8E8 being 59624 value seen as well.

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Reply 190 of 193, by CircuitRewind

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keenmaster486 wrote on 2025-02-06, 16:04:

Voltage stability problem?

I highly doubt it in my case. Symptoms don't line up. And when I've tested voltage stability for other things with this rig prior, it was perfectly fine. Additionally, I've put some serious hours into this machine without the CRT Terminator, and every other thing is functioning as expected.

I have however ordered more testing hardware so will be able to do a deeper dive here in a couple weeks.

Reply 191 of 193, by clb

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Thanks, great data. That got me on the right track to look for issues.

I found one problem in the test program itself. On my 16MHz 286 PC (which I didn't originally see on my 80 MHz 486 PC), right after issuing an OUT I/O write command, I need to wait for a few NOPs, before issuing a IN I/O write command to read data back.

Otherwise without pausing between writes and reads, I got exactly the same problem as you were seeing - the reads would come out incorrect.

Uploaded a fixed test program now that adds 5 NOP commands after an I/O write, before issuing the next I/O read: https://github.com/juj/crt_terminator/commit/ … 2cfc9ae5R75-R79 . That fixes the test on my 286.

However, that is possibly not the root problem in the equation - but hopefully will help clear the smoke to zoom in to the remaining problems.

The hypothesis here is that there is an ISA I/O conflict with other hardware. And after removing the peripherals and the conflict, this test program problem unsurfaced.

So please give the above listed updated version a try. Hopefully it will start to report passes for the tests, and we can see what failures remain.

For the next steps, I am working on building a new firmware that has a battery of built-in diagnostics in it that can detect ISA bus conflicts, and allows disabling CRT Terminator's 8bpp palette path to rule out any conflict there. I'll post it soon once it is ready for testing.

Reply 192 of 193, by CircuitRewind

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clb wrote on 2025-02-06, 19:17:

Uploaded a fixed test program now that adds 5 NOP commands after an I/O write, before issuing the next I/O read: https://github.com/juj/crt_terminator/commit/ … 2cfc9ae5R75-R79 . That fixes the test on my 286.

Nope, still lots of "232" in every single returned value.

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Reply 193 of 193, by clb

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Oh, bummer. 😒

No trouble though, we do have a couple of leads on the root cause. I am working on a new firmware that should be done over the weekend. It will help diagnose these issues on the ISA bus from several different angles. I'll reply once that is ready (instructions for flashing are at https://oummg.com/manual/#firmware_update )

That should be able to help us differentiate whether there might be something incompatible with the motherboard or the integrated adapter, or whether to take the suspect to be a problem with the CRT Terminator card instead.