Cumulus Issues

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Dbug
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Re: Cumulus Issues

Post by Dbug » Wed Jul 16, 2014 11:14 am

NightBird wrote:Only chance? I do not think so, because IC12 is D7 (bit 7), and D7 is a little bit special on Microdisc. This line can be driven, and maybe the Cumulus is 'more severe' than Microdisc (Cumulus schematic quickly examined but did not saw a specific problem).
So, could it be a problem with timings in the Cumulus firmware when overlay is switched on/off?

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Re: Cumulus Issues

Post by Steve M » Wed Jul 16, 2014 12:02 pm

I was talking to someone who had some issues with 2600 RAM chips. There were some on a board I sold him and he said they were all a problem.

I've had other Orics with 2600 that seem to work fine, so there is maybe different tolerances?

Seem to recall someone recommending that the RAM should be used in pairs of the same kind. Is there any truth in that???

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Re: Cumulus Issues

Post by Godzil » Wed Jul 16, 2014 1:10 pm

Steve M wrote:I was talking to someone who had some issues with 2600 RAM chips. There were some on a board I sold him and he said they were all a problem.

I've had other Orics with 2600 that seem to work fine, so there is maybe different tolerances?
2600?
Seem to recall someone recommending that the RAM should be used in pairs of the same kind. Is there any truth in that???
You mistake with RAM modules for the PC insdustrie like it was on first gen Pentium.

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Re: Cumulus Issues

Post by NightBird » Wed Jul 16, 2014 10:09 pm

Dbug wrote:
NightBird wrote:Only chance? I do not think so, because IC12 is D7 (bit 7), and D7 is a little bit special on Microdisc. This line can be driven, and maybe the Cumulus is 'more severe' than Microdisc (Cumulus schematic quickly examined but did not saw a specific problem).
So, could it be a problem with timings in the Cumulus firmware when overlay is switched on/off?
When I put the probe scope on D7 (IC12 pin 14) with a 'faulty' DRAM, the system works (with the 3 'faulty' DRAM, works on 2)! Something disturbs D7? How to solve it (add a couple of resistor/capacitor, and where)?

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Re: Cumulus Issues

Post by Godzil » Thu Jul 17, 2014 11:05 am

NightBird wrote:
Dbug wrote:
NightBird wrote:Only chance? I do not think so, because IC12 is D7 (bit 7), and D7 is a little bit special on Microdisc. This line can be driven, and maybe the Cumulus is 'more severe' than Microdisc (Cumulus schematic quickly examined but did not saw a specific problem).
So, could it be a problem with timings in the Cumulus firmware when overlay is switched on/off?
When I put the probe scope on D7 (IC12 pin 14) with a 'faulty' DRAM, the system works (with the 3 'faulty' DRAM, works on 2)! Something disturbs D7? How to solve it (add a couple of resistor/capacitor, and where)?
This is clearly not a good sign, may mean there is a ground fault somewhere.

You should do a ground check to verify that there is no too high resistance between two (or more) ground point.

Does it do the same if you touch pin 2 (Data In) (Pin 14 is Data Out)

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Re: Cumulus Issues

Post by Steve M » Thu Jul 17, 2014 3:50 pm

Godzil wrote:
2600?
It was an INMOS memory chip that I've seen on later Orics.
http://www.ebay.co.uk/itm/INMOS-IMS2600 ... 0632692122

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Re: Cumulus Issues

Post by Godzil » Thu Jul 17, 2014 4:28 pm

Never saw one of them :)

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Re: Cumulus Issues

Post by NightBird » Sat Jul 19, 2014 4:32 pm

Godzil wrote:This is clearly not a good sign, may mean there is a ground fault somewhere.

You should do a ground check to verify that there is no too high resistance between two (or more) ground point.

Does it do the same if you touch pin 2 (Data In) (Pin 14 is Data Out)
Faulty DRAM with probe alone (1Mohm||18pF) is working:
faulty_DRAM_and_scope_probe_alone.png
Remarq: IC12 pin 2 and 14 are linked (please see the Oric schematic).

Maybe the problem is DRAM tolerance? I used a 'faulty' DRAM on another unit and it is working...
Try to change IC12 when the Oric has randomized character on boot (try different DRAM trades)...

Note that if only IC12 needs to be replaced, is there a timing problem with D7?

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Re: Cumulus Issues

Post by NightBird » Sat Jul 19, 2014 4:37 pm

Dbug wrote:So, could it be a problem with timings in the Cumulus firmware when overlay is switched on/off?
Maybe? With the 'probe jig', and the demo file 'PushingTheEnvelope', when I remove the probe, the system is working some seconds (about 2 to 5) then crash.

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Re: Cumulus Issues

Post by metadata » Mon Jul 28, 2014 11:02 am

peacer wrote: My PSU is giving 12 V and over 12 VA, not 9 V. it runs Oric and microdisc drive at the same time well. But as you know Cumulus doesn't work..
so your powersupply only have 1A at 12V? And the VA is on the inputside of the supply, right? So you have not 1A output maybe only 60-80% of 1A at the output side?

have you tried another powersupply?

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Re: Cumulus Issues

Post by peacer » Mon Jul 28, 2014 12:19 pm

I am on vacation now and my Oric is away..

I am not good on hardware. That is what my dad said as my PSU has 12 v voltage and 12 VA amperage.. I don't know if this is input or output..

On the other hand.. We have tried another PSU connected to an accumulator with changable - adjustable voltage output and that does not work either. With that power supply, decreasing of voltage from 12 to 9 creates artifacts on the display with lines suitable with low voltage..

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Re: Cumulus Issues

Post by jorodr » Sun Aug 03, 2014 11:28 am

Hello,
I'm unhappy to say that my Cumulus had stop working. It was used only 2-3 times for about 4-5 minutes since buying it, but now when I tried to start and it is absolutely dead.
Is there any support for these devices?

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Re: Cumulus Issues

Post by Dbug » Sun Aug 03, 2014 2:10 pm

jorodr wrote:Hello,
I'm unhappy to say that my Cumulus had stop working. It was used only 2-3 times for about 4-5 minutes since buying it, but now when I tried to start and it is absolutely dead.
Is there any support for these devices?
I guess by "absolutely dead" you mean that the screen does not show anything?
Does the Oric boots like if there was nothing connected at all on the bus?

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Re: Cumulus Issues

Post by metadata » Thu Aug 07, 2014 1:22 pm

jorodr wrote:Hello,
I'm unhappy to say that my Cumulus had stop working. It was used only 2-3 times for about 4-5 minutes since buying it, but now when I tried to start and it is absolutely dead.
Is there any support for these devices?
does the screen backlight turn on when you power it up?
Have you tried to reflash the firmware?

Before you send it back and i send you a new one we can test a few things out. Maybe we can get it back to work.

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Re: Cumulus Issues

Post by jorodr » Thu Aug 07, 2014 1:47 pm

Metadata it's not your fault.
Me and my friend Ivan (iss) have realised that the screen connector is unsoldered. Then we tried to boot "in blind" and voila - the image booted. Then Ivan said:
"Let's see if it works on Pravetz 8D."
I have turned the buffer board (you know Pravetz 8D motherboard is face up) and then everything had stopped working. No more asking for insert disc, just lines on the screen. Anyway, iss told me that it's Cumulus had crashed in same way with Pravetz 8D and the Cumulus screen was black. Afret reflashing the PIC the screen light up, suggesting to choise the disc image, but nothing more. It's seems that the matrix is don't working too. Unfortunately I have troubles compiling the source. WDC 1793 is compilling correct, but Cumulus.vhdl is not. Is there some jed file anywhere?
The other question is: I have JTAG cable with TTL levels 5V. Is it possible to program the matrix with it or must low down the program levels to 3.3V?

Thanks in advance,
George

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