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.

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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."

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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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Re: New Member and New Oric Atmos Owner

Post by SpaceFlightOrange » Sun Dec 08, 2019 11:47 am

signal-2019-12-08-085024.jpeg
signal-2019-12-08-085024.jpeg (199.07 KiB) Viewed 119 times
Thank You, and, Goodnight :D

RAM arrived from Bulgaria (Finally) NOS Fujitsu MB8264-15. It's been sitting there for a few days to be honest, but I was trying to get the Spectrum refurb done, but the keyboard was giving me some grief (its in a Lo>>Profile Keyboard case, and the tails had been badly repaired resulting in some solder tabs being destroyed, and when reassembling it, I struggled to get even pressure and the odd key didn't work).

I pulled the dodgy Chinese ram out and continuity tested all the address lines between the ULA and the Multiplexers, from the multiplexers to the ram, the address lines between the ULA and the CPU, the RAM and the CPU and the RAM and the VIA. all were ok

I then individually tested the new chips using DRAMArduino and fitted them. I booted using Mike's diagnostic ROM. on first startup I get nice straight vertical black and white bars. All tests up to the printer one passed. I stopped there because I haven't yet made the loopback connectors so that's the next thing.

Swapped the original ROM back in and started up fine, and "ping" and "explode" work! happy days.

So I now have a bunch of spares available (ULA, ROM, CPU, VIA, AY, and more RAM thats due to arrive). Unfortunately I have no way of testing the spare AY and I'm not desoldering the one from the Oric if I can help it. I am able to test the rest (CPU and VIA in the Beeb)

The original RAM was clearly bad from the beginning, evidenced by the dodgy $ being displayed randomly around the screen and the available memory only being 315 bytes free. Me shorting the regulator cured its headache for good, but how I never killed anything else (apart from the multiplexers, possibly? I'll re-test the originals), I have no idea!!

Thank you all so much for your support. Couldn't have done it without you.
Last edited by SpaceFlightOrange on Sun Dec 08, 2019 1:01 pm, edited 1 time in total.

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Vyper68
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Re: New Member and New Oric Atmos Owner

Post by Vyper68 » Sun Dec 08, 2019 12:30 pm

Great result!

I bought my DRAM and spare ULA as well as a 8912 from Bulgaria. Does this mean someone has a load of Pravetz spares?
Bazinga!

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iss
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Re: New Member and New Oric Atmos Owner

Post by iss » Sun Dec 08, 2019 2:14 pm

@SpaceFlightOrange: Great picture! Congrats for the result and happy time with your Oric.
Vyper68 wrote:
Sun Dec 08, 2019 12:30 pm
I bought my DRAM and spare ULA as well as a 8912 from Bulgaria. Does this mean someone has a load of Pravetz spares?
Yes, there should be lot. As I already said all chips on eBay with sellers from Bulgaria are fine. They are remains after Pravetz 8D production was stopped and someone was clever to get them for cents (or maybe for free?). I don't know personally the seller but it seams he is honest enough and reliable as source for Oric parts. IMO the prices are bit high but this is how the monopoly works. :(

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Chema
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Re: New Member and New Oric Atmos Owner

Post by Chema » Sun Dec 08, 2019 4:32 pm

Great news! Congratulations. Enjoy your machine!

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mikeb
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Re: New Member and New Oric Atmos Owner

Post by mikeb » Sun Dec 08, 2019 6:50 pm

Excellent news -- another one rescued :)

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