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Chaintech 6VIA5T-D100A + AWE64 (CT4520) issue fix

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First post, by evgs

Posted on 
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Hi, vogons.
Chaintech 6VIA5T-D100A is a very good mainboard for building retro-machine (support Tualatin, AGP4x, and have ISA for old sounblaster-compatible soundcards)

But it have an issue, and this info may be interesting:
6VIA5T-D100A doesn't recognize SB AWE64 (CT4520)
I've tried to set IRQ/DMA manually in BIOS, tried different BIOS versions too.
I've tried 2 same motherboards and 2 soundcards but nothing helped.

People on the forum wrote they tried to flash different bios from
other motherboards (gigabyte GA-6VTXE, acorp 6VIA85T) based on same chipset and it helped. AWE64 was detected, but other bugs appeared.

Root of the problem here:
https://www.phantom.sannata.org/viewtopic.php … =499034#p499034

This mainboard doesn't have working 14MHz on ISA
This is BIOS bug, it doesn't sent 14MHz to ISA
and here is hardware fix:

resistor is 100-220 Ohm.
need to cut trace 2:

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Reply 1 of 1, by Tiido

Posted on 
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Rank l33t
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l33t

I originally did the mod to get CMI8330 based cards to work which also rely on 14MHz being present on the ISA slot, that's when I discovered that the signal was not oscillating. Luckily the second PLL output could be used to fix the issue.

T-04YBSC, a new YMF71x based sound card & Official VOGONS thread about it
Newly made 4MB 60ns 30pin SIMMs ~
mida sa loed ? nagunii aru ei saa 😜

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