New Member and New Oric Atmos Owner

If you want to ask questions about how the machine works, peculiar details, the differences between models, here it is !
How to program the oric hardware (VIA, FDC, ...) is also welcome.
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mikeb
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Re: New Member and New Oric Atmos Owner

Post by mikeb » Mon Dec 02, 2019 5:34 pm

SpaceFlightOrange wrote:
Mon Dec 02, 2019 12:25 am
Hopefully some replacements will turn up this week.
If it's still no go, then I think we're back to first principles -- get out the continuity tester, checking all 8 "row/col" addresses from the ULA are correctly connected to the correct pins on the multiplexer, that the other 8 address lines from the CPU into the multiplexer are connected correctly, that they then connect to each and every DRAM chip, that each DRAM chip's data IN and OUT pins are tied to each other and to the buss, that the R/W line on each and every DRAM is being driven ... same with the RAS and CAS lines. You've changed almost every chip in this path, and it still isn't working ...

It's always possible to exchange a faulty chip in a working board, for a working chip in a now-faulty board :(

SpaceFlightOrange
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Re: New Member and New Oric Atmos Owner

Post by SpaceFlightOrange » Tue Dec 03, 2019 1:51 pm

Thanks mike. I’ll get on that while I’m waiting.

I did check the dram lines when I socketed them but I didn’t check from the multiplexer to the ULA. But I’ll go back over everything.

omelette
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Re: New Member and New Oric Atmos Owner

Post by omelette » Thu Dec 05, 2019 3:01 am

Fascinating read, this thread. Not much to add except to say that I bought 2 8912 chips from China recently, for use in resurrecting some Oric-1's. They came well packaged in an anti-static tube. Removed one from tube, plugged it into Oric, powered it on and was treated to a constant tone, with no keys working. Plug the second one into the Oric and it worked perfectly! Imo, there seems to be little or no quality-control in operation from most of these cheap Chinese component manufacturers. So has Phil used to say on HSB, "let's be careful out there."

SpaceFlightOrange
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Re: New Member and New Oric Atmos Owner

Post by SpaceFlightOrange » Thu Dec 05, 2019 11:00 am

omelette wrote:
Thu Dec 05, 2019 3:01 am
Imo, there seems to be little or no quality-control in operation from most of these cheap Chinese component manufacturers. So has Phil used to say on HSB, "let's be careful out there."
I think you’re right. Best guess the ram I have is because they all appear to work they can’t be managing the advertised speed.

I’ve just bought a NOS 8912 from a UK Supplier so hopefully it’s ok. I can’t test it unfortunately as I haven’t socketed this yet and I don’t want to go down that road unless I have to.

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