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Pocket386 ISA Expansion board orientation?

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First post, by Tumerboy

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I snagged one of the Pocket386's off AliExpress, and with it, one of the ISA8-EXP-01 expansion boards. This is a board that connects via ribbon cable to the back of the Pocket386, and then has 3x 8bit ISA slots for use with. . . whatever.

These showed up yesterday, and I have an old ISA Sound Blaster in the archives, so I was going to plug it together and see if I could get some better audio out of it.

Problem is, 8-bit ISA isn't keyed, and can be inserted either direction, and the board has no obvious marking telling me which way is which.

I'm not as experienced with this stuff as most of you, but my instinct says plugging a card in backwards might be bad. Is there some way of telling which way is which on this? There are markings at one end of each slot (You can kind of see them at the top of the picture) indicating an "A" side and a "B" side to each slot? But I'm not sure if that corresponds to something on the card?

I'd appreciate any help or insights y'all can offer. Thanks

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Reply 1 of 3, by Horun

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with a digital volt meter check the ohms from slot to ground. you can use on of the soldered mount circles on each corner as they should be grounded....
there are 3 grounds in ISA 8 bit on the "B" side and no grounds on the "A" side. they are pin 1, 10 and 31.
just check one slot as all will be same. once you know which side has the grounds you know which side is the "solder side" or B side. components are on A side.....
hope that makes sense...

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 3 of 3, by Tumerboy

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Thanks folks, I was able to get it plugged together. With no drivers I could hear midi play beautifully through the board, but sounds came through the Pocket386's speakers. I tried a couple of different combos of turning the internal amp/opl on and off, but to no avail.

I tried installing regular dos SB16 drivers, but it complains that I'm actually in Windows 95 (I'm just working with the original CF card, I'll make my own if need be).

Then I tried installing UniSound, and it recognizes the card on boot, but nothing else seems to. The only sounds I've been able to get out of the speakers is garbage tweets and pops.

I'll play with it more and see if I can get something working. I should probably just make up my own dos install CF sooner rather than later anyway.

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