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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.

Unisys SG2400:
- CPU: 486DX2-66
- RAM: 16MB (0 waitstates)
- VGA: Diamond SpeedSTAR VGA (ET4000AX 1MB ISA)
- Audio: Sound Blaster 16 CT2800
- 8GB SSD
- ISA USB card (for USB sticks)
- MR BIOS

Reply 2 of 13, 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. 🙁

Unisys SG2400:
- CPU: 486DX2-66
- RAM: 16MB (0 waitstates)
- VGA: Diamond SpeedSTAR VGA (ET4000AX 1MB ISA)
- Audio: Sound Blaster 16 CT2800
- 8GB SSD
- ISA USB card (for USB sticks)
- MR BIOS

Reply 3 of 13, 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.

Visit my AmiBay items for sale (updated: 2025-03-14). I also take requests 😉
https://www.amibay.com/members/kixs.977/#sales-threads

Reply 4 of 13, 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.

Unisys SG2400:
- CPU: 486DX2-66
- RAM: 16MB (0 waitstates)
- VGA: Diamond SpeedSTAR VGA (ET4000AX 1MB ISA)
- Audio: Sound Blaster 16 CT2800
- 8GB SSD
- ISA USB card (for USB sticks)
- MR BIOS

Reply 5 of 13, 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 13, 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.

Unisys SG2400:
- CPU: 486DX2-66
- RAM: 16MB (0 waitstates)
- VGA: Diamond SpeedSTAR VGA (ET4000AX 1MB ISA)
- Audio: Sound Blaster 16 CT2800
- 8GB SSD
- ISA USB card (for USB sticks)
- MR BIOS

Reply 7 of 13, 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 13, 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.

Unisys SG2400:
- CPU: 486DX2-66
- RAM: 16MB (0 waitstates)
- VGA: Diamond SpeedSTAR VGA (ET4000AX 1MB ISA)
- Audio: Sound Blaster 16 CT2800
- 8GB SSD
- ISA USB card (for USB sticks)
- MR BIOS

Reply 9 of 13, 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 […]
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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.)

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

Visit my AmiBay items for sale (updated: 2025-03-14). I also take requests 😉
https://www.amibay.com/members/kixs.977/#sales-threads

Reply 10 of 13, 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.

Unisys SG2400:
- CPU: 486DX2-66
- RAM: 16MB (0 waitstates)
- VGA: Diamond SpeedSTAR VGA (ET4000AX 1MB ISA)
- Audio: Sound Blaster 16 CT2800
- 8GB SSD
- ISA USB card (for USB sticks)
- MR BIOS

Reply 11 of 13, by 8bitbubsy

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kixs: I flashed the card with your BIOS dump now, but it still doesn't post if the VLB Multi-I/O card is present, but it works fine without it (so the BIOS seems to be compatible, and I'll stick with it since it's newer).
I'm getting an ISA Multi-I/O card for free from a friend. I'll update you in this thread if it works with that one.

Unisys SG2400:
- CPU: 486DX2-66
- RAM: 16MB (0 waitstates)
- VGA: Diamond SpeedSTAR VGA (ET4000AX 1MB ISA)
- Audio: Sound Blaster 16 CT2800
- 8GB SSD
- ISA USB card (for USB sticks)
- MR BIOS

Reply 12 of 13, by 8bitbubsy

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Update: Got my ISA Multi-I/O card, and now the machine boots with the S3 Vision864 card.
I had to revert to the original VGA BIOS because I got corruption in some text-mode programs (like Impulse Tracker 2).

By the way, the HDD read/write speed in DOS went from 4MB/s to 2MB/s when using an ISA card instead of VLB. So yeah, it really does make a difference. 2MB/s is more than enough, though. 😀

Unisys SG2400:
- CPU: 486DX2-66
- RAM: 16MB (0 waitstates)
- VGA: Diamond SpeedSTAR VGA (ET4000AX 1MB ISA)
- Audio: Sound Blaster 16 CT2800
- 8GB SSD
- ISA USB card (for USB sticks)
- MR BIOS

Reply 13 of 13, by kixs

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I guess it's a compatibility issue but in the end it's important it works 😉

Also interesting the HDD transfer rate dropped so much. When I tested a few VLB & ISA I/O cards there wasn't a big difference.

Visit my AmiBay items for sale (updated: 2025-03-14). I also take requests 😉
https://www.amibay.com/members/kixs.977/#sales-threads