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First post, by 8bitbubsy

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I just got a miroCRYSTAL 20SD (S3 Vision864 2MB , old card revision), and I found out that my system won't POST if my VLB Multi-I/O card (PTI-255W v1.2, Winbond chipset) is also connected. With an older S3 805 GPU, I have no issues whatsoever.

Any idea what could cause this? I've tried different RAM, restoring default BIOS settings, changing VLB waitstates on both motherboard and GPU+I/O card, cleaned connectors, tried a different CPU (486DX2-66 -> Cyrix DX2-66), etc. I also tried to disable everything on the Multi-I/O card, but still no POST. The only thing that works is if I remove the multi-I/O card.

EDIT: Also tried to swap the cards, tried all three VLB slots.

The motherboard is a "SIS 486G 3.3/5V Ver:E".

Last edited by 8bitbubsy on 2021-11-25, 13:20. Edited 2 times in total.

486:
- Motherboard: "SIS 486G 3.3/5V Ver:E" w/ 256kB L2 cache
- CPU: Intel 486DX2 66MHz (soon DX4-100)
- RAM: 32MB FPM 60ns
- VGA: S3 805 1MB VLB (soon S3 Vision864 2MB VLB)
- Audio: SB16 CT2800 (real OPL3)
- ISA PS/2 mouse card

Reply 2 of 10, by 8bitbubsy

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kixs wrote on 2021-11-25, 13:19:

Did you try in different slots (swap I/O card with 20SD)?

Yes I did, I forgot to mention this in the post.

EDIT: One thing I'm going to try is another Vision864 VGA BIOS. The one on the card is a very old version (v1.00-04). I just have to wait for a W27E257-12 chip to arrive, and that takes time. 🙁

486:
- Motherboard: "SIS 486G 3.3/5V Ver:E" w/ 256kB L2 cache
- CPU: Intel 486DX2 66MHz (soon DX4-100)
- RAM: 32MB FPM 60ns
- VGA: S3 805 1MB VLB (soon S3 Vision864 2MB VLB)
- Audio: SB16 CT2800 (real OPL3)
- ISA PS/2 mouse card

Reply 3 of 10, by kixs

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You can always use an ISA I/O card. If you don't use special drivers for VLB I/O card, there won't be any difference.

My Amibay | - Updated on 2021-12-01 | Requests also possible

Reply 4 of 10, by 8bitbubsy

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I only use MS-DOS and Windows 3.11 without any VLB IDE driver, so yeah, this is a solution too. However, I want to try a different VGA BIOS first.

486:
- Motherboard: "SIS 486G 3.3/5V Ver:E" w/ 256kB L2 cache
- CPU: Intel 486DX2 66MHz (soon DX4-100)
- RAM: 32MB FPM 60ns
- VGA: S3 805 1MB VLB (soon S3 Vision864 2MB VLB)
- Audio: SB16 CT2800 (real OPL3)
- ISA PS/2 mouse card

Reply 5 of 10, by retardware

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One of the reasons why I don't consider VLB good.
It's just gambling, especially if you use cards from inferior manufacturers like Miro, in this case.
Maybe try a Spea Mercury VLB instead? Spea usually made outstandingly good stuff.
(Miro bought cheap Taiwan stuff and sold it as "German quality". Drivers were just abysmal. Many of their monitors were just garbage, for example.)

Last edited by retardware on 2021-11-25, 16:25. Edited 1 time in total.

Reply 6 of 10, by 8bitbubsy

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No way, I already spent way too much money on this. It should be a solid performer once I get the system up and running.

486:
- Motherboard: "SIS 486G 3.3/5V Ver:E" w/ 256kB L2 cache
- CPU: Intel 486DX2 66MHz (soon DX4-100)
- RAM: 32MB FPM 60ns
- VGA: S3 805 1MB VLB (soon S3 Vision864 2MB VLB)
- Audio: SB16 CT2800 (real OPL3)
- ISA PS/2 mouse card

Reply 7 of 10, by TheMobRules

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Try setting your bus speed to 25MHz and see if you get a POST with both cards at that speed. That could help troubleshoot the issue.

Also, what are the jumpers on your motherboard and graphics card for controlling the VLB delay/waitstates? Usually there should be at least 2 settings in the motherboard (one for the waitstates and one for <= or > 33MHz).

Reply 8 of 10, by 8bitbubsy

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There's a setting for VLB waitstates, and a setting for FSB (not for setting the FSB, but a jumper that needs to be set accordingly).
My FSB is 33MHz, and waitstates is set to 0, and the Mhz thing is set to <=33. I have tried all possible combination on it, and it didn't help.

However, I have not tried to set an FSB of 25MHz. I'll try tomorrow.

486:
- Motherboard: "SIS 486G 3.3/5V Ver:E" w/ 256kB L2 cache
- CPU: Intel 486DX2 66MHz (soon DX4-100)
- RAM: 32MB FPM 60ns
- VGA: S3 805 1MB VLB (soon S3 Vision864 2MB VLB)
- Audio: SB16 CT2800 (real OPL3)
- ISA PS/2 mouse card

Reply 9 of 10, by kixs

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retardware wrote on 2021-11-25, 15:57:
One of the reasons why I don't consider VLB good. It's just gambling, especially if you use cards from inferior manufacturers li […]
Show full quote

One of the reasons why I don't consider VLB good.
It's just gambling, especially if you use cards from inferior manufacturers like Miro, in this case.
Maybe try a Spea Mercury VLB instead? Spea usually made outstandingly good stuff.
(Miro bought cheap Taiwan stuff and sold it as "German quality". Drivers were just abysmal. Many of their monitors were just garbage, for example.)

I don't have bad experiences with Miro cards. On the other hand I can't say much good about SPEA cards - unfortunately 🙁

My Amibay | - Updated on 2021-12-01 | Requests also possible

Reply 10 of 10, by 8bitbubsy

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TheMobRules wrote on 2021-11-25, 20:33:

Try setting your bus speed to 25MHz and see if you get a POST with both cards at that speed. That could help troubleshoot the issue.

I set FSB to 25MHz, still no post. Another interesting fact is that if I connect another VLB GPU while the S3 Vision864 is connected, the system posts, so it really sounds like it's the VLB multi-I/O card itself that somehow makes a conflict with this GPU.

486:
- Motherboard: "SIS 486G 3.3/5V Ver:E" w/ 256kB L2 cache
- CPU: Intel 486DX2 66MHz (soon DX4-100)
- RAM: 32MB FPM 60ns
- VGA: S3 805 1MB VLB (soon S3 Vision864 2MB VLB)
- Audio: SB16 CT2800 (real OPL3)
- ISA PS/2 mouse card