anybody have a idea what this hw modification is supposed to do? \ VOGONS

anybody have a idea what this hw modification is supposed to do?

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First post, by treeman

Posted on 2019-07-17, 23:58

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this is a 486 vlb motherboard with no cache, it is a dca tech (direct cache access) if it makes any difference.

I don't remember if this board ever booted but it is not posting now and I noticed a hardware mod on what I think is one of the buffers or hex inverter near the cpu. I am very curious what it is supposed to do, and if I reverse it maybye it will boot?

The chip in question is a QUAD 2-INPUT AND GATE FAST SCHOTTKY TTL

so from my poor understanding it is a gate chip that lets data through 1 way but not back the other?

anyway here is 2 pictures, one unmodified and second where I circled the 2 jumper cables that have been attached to the chip, the original pin removed and rerouted to a resistors

Reply 1 of 7, by Tiido

Posted on 2019-07-18, 00:06

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This is a factory fix and reverting it will most probably cause nothing to work at all. It probably exists to correct some timing issue or maybe an outright routing mistake.

T-04YBSC, a new YMF71x based sound card & Official VOGONS thread about it
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Reply 2 of 7, by retardware

Posted on 2019-07-18, 00:07

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I guess just some factory fix for the first series PCB.
I guess there happens nothing special. Just some pull-up of one gate input pin.
What chipset, if I may ask?

Reply 3 of 7, by treeman

Posted on 2019-07-18, 00:08

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I see, thank you the confirmation

Reply 4 of 7, by treeman

Posted on 2019-07-18, 00:09

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both the chips have a yellow sticker which says DCA octek technologies

Reply 5 of 7, by retardware

Posted on 2019-07-18, 00:34

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Mhh, sounds like Headland chipset.
I am searching for one such, so, in case you want to sell it, let me know.

Reply 6 of 7, by treeman

Posted on 2019-07-18, 00:44

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i took the stickers off out of curiosity and they are
LSI HT321 and HT342

thanx for the offer but sorry I only collect

Reply 7 of 7, by retardware

Posted on 2019-07-18, 01:05

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yes, Headland "Shasta" chipset.
As they already are labelled LSI, that mobo is made after Headland got bought by LSI.

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