Issue with MSI 3113-7 386DX Mainboard \ VOGONS

Issue with MSI 3113-7 386DX Mainboard

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First post, by egrath

Posted on 2023-08-12, 20:00

egrath Offline

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Hi,

i just finished my first ever retro PC build to play some games i used to play in the late 80s and early 90s. It's based around a MSI 3113-7 386 Mainboard and is working fine generally. But there's one issue:

It just runs at 16 Mhz (according to Checkit 3) even though a 33 Mhz CPU is installed. The CPU was already installed when i got the board and the previous owner didn't knew anything about it, so i can't tell for sure if the jumpers are in the correct positions. Unfortunately, there is no manual available and no printing on the silk screen to indicate which jumpers need to be set in which position.

This is the board in question:

The attachment board.jpg is no longer available

I assume the block of 4 jumpers bottom next to the cache module to be the selectors, but i'm not sure about it and don't want to risk damaging the board. Anyone has the same board and can give me any hints? Additionally, what might be interesting or could help: There's a header on the board for the usual indicators like power led, reset, and so on. There's also one for "TURBO". If this one isn't closed the board does not boot at all.

With best regards,
Egon

Reply 1 of 8, by rasz_pl

Posted on 2023-08-13, 00:19

rasz_pl Offline

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Have you tried Turbo switch on/off?

https://github.com/raszpl/FIC-486-GAC-2-Cache-Module for AT&T Globalyst
https://github.com/raszpl/386RC-16 memory board
https://github.com/raszpl/440BX Reference Design adapted to Kicad
https://github.com/raszpl/Zenith_ZBIOS MFM-300 Monitor

Reply 2 of 8, by egrath

Posted on 2023-08-13, 07:15

egrath Offline

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Yes, does not boot.

Reply 3 of 8, by TheMobRules

Posted on 2023-08-13, 08:22

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The picture in The Retro Web (https://theretroweb.com/motherboards/s/msi-3113-7) shows a board apparently configured for 25MHz and all 4 jumpers in the JP2 block are closed. You could try that, if that configuration works for that board (50MHz oscillator divided by 2) it should be no different on yours for 33MHz (66MHz oscillator divided by 2).

Reply 4 of 8, by CoffeeOne

Posted on 2023-08-13, 14:43

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egrath wrote on 2023-08-13, 07:15:

Yes, does not boot.

So when Turbo is on, it does not boot?

Reply 5 of 8, by egrath

Posted on 2023-08-18, 16:28

egrath Offline

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Yes, that's exactly the behavior of the device. In the meantime i was able to solve the issue.

Problem seems to be related the way the BIOS handles it's CMOS settings when the backup battery was disconnected. Essentially, there are two BIOS parts in the device: The basic one, which let's you specify basic parameters like date, time, floppy and hdd configuration. And the second part, accessible through another keyboard shortcut, for advanced settings like bus frequency divider, cas latency and so on. As soon as the device lost it's cmos ram content because the backup battery is removed, there's probably garbage in this area of the cmos ram and the bios does not handle it correctly - and only boots with turbo off. As soon as you write the default values once, the system works flawless at turbo speed. The behavior is reproducable by disconnecting mains and the backup battery.

Maybe this description helps others who suffer from similar issues.

Reply 6 of 8, by root42

Posted on 2024-10-10, 07:18

root42 Offline

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Hi Egon,

egrath wrote on 2023-08-12, 20:00:

This is the board in question:

The attachment board.jpg is no longer available

Do you still have the board? Would it be possible to post high quality pictures of the top and bottom side of the cache module? Those seem to be very rare, and it might help people in recreating them.

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Reply 7 of 8, by rasz_pl

Posted on 2024-10-10, 08:07

rasz_pl Offline

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TheMobRules wrote on 2023-08-13, 08:22:
The picture in The Retro Web (https://theretroweb.com/motherboards/s/msi-3113-7

Wrong Cache description. 82C310 has 128Byte of 2-way set associative cache build in. Whole 32 cache pages hehe 😮 Would love to see how much difference 32 pages make vs no cache in something like FastDoom.
OP picture has 64KB module fitted, tracing even from this single lowres picture shouldnt be insurmountable with available 310 pinout.

Reply 8 of 8, by root42

Posted on 2024-10-10, 08:30

root42 Offline

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rasz_pl wrote on 2024-10-10, 08:07:

TheMobRules wrote on 2023-08-13, 08:22:
The picture in The Retro Web (https://theretroweb.com/motherboards/s/msi-3113-7

Wrong Cache description. 82C310 has 128Byte of 2-way set associative cache build in. Whole 32 cache pages hehe 😮 Would love to see how much difference 32 pages make vs no cache in something like FastDoom.
OP picture has 64KB module fitted, tracing even from this single lowres picture shouldnt be insurmountable with available 310 pinout.

Exactly, I was hoping that this would be possible. Board looks rather simple.

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