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Cbm 2001 Pet strange boot

Dave_C78 said:
I don't have any tester board....i have only Pettester :(
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A ROM/ROM board, either a ROMulan RAMulator, BiTFixer ROMulator or a Tynemouth ROM/RAM or equivalent are a handy tool. 9 out of 10 owners say it reduces their level of desperation.
Even then... some problems require additional tools... logic analyser, multi-channel scope etc...
 
No he doesn't. I have been trying to persuade Dave to increase his stock of test equipment since he is repairing every dead PET in Italy :)...

One possibility, to rule out the ROMs, is to put them into another (working) PET (if they are socketed also). If they work for a day, they must be good.

If they are not socketed, you can put them one at a time into the option ROM socket and write a little bit of BASIC to continuously checksum it in a loop. If the checksum changes during the test period, it is suspect.

I seem to remember some BASIC code floating about for this somewhere. @dave_m do you know where?

Dave
 
Again I think the suggestion I have made twice previously would solve the problem if it is ROM related (or PIA too).

Simply create a new complete set of good ROMs, that is easy with the GQ-4x he has and some 2716 and 2532 ROMS . Replace them all at the same time and fit two new PIA's for that matter.They are all in sockets so its easy.

Then soak test the PET.

If the problem is still there, then obviously it is not ROM or PIA related.

If the problem vanishes, then re-insert the original ROMs and PIA's one by one with a soak test in between. You will soon find the one/s that were faulty this way, and it may be more than one them.
 
The ROM checksums are correctly shown in PETTESTER somewhere above so I'm not convinced this is a ROM problem.

I would like to see PETTESTER running for a while against RAM; the leap towards getting it all running was IMHO premature and likely to lead to confusion and worse... D.........
 
I'm desperate!
I run Pet only with Pettester eprom on UD9 and char rom but i have always same fault....
I tried also with Ice spray on all roms and rams but nothing changes....
 
Now Pettester give me this error (in picture)... i think that's caused by bad ram or logic....right?
 

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I can see it now you have added it...

028b is the 16-bit address in memory that the fault occurred at.

The next byte (08) has a bit set indicating the memory bit that was in error (in this case 08 = 00001000 = data bit 3.

Note these numbers down in your notebook (along with the next byte (38) for completeness).

Press the reset button and wait for it to error again...

Keep doing this to see if the error bit is consistent or across all of the bits, or across a number of bits. Ditto for the addresses; are they always in bank 0 or 1 or both or are they grouped together.

You now have to be patient and do some graft to collect evidence...

Dave
 
Ok Dave thanks....I suspect there is some fault on the rams or correlated logic....but which?? :(
 
this time it froze at this point:
 

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In this point i pressed reset button and
the test still crashed with this error... Please give me an exorcist!!!
 

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At this stage it could still be anything.

I am afraid we need to simplify the test programs to get rid of the RAM altogether and to prove the kernel ROM, CPU and video RAM.

Basically, a pure and simple test program that constantly writes the same thing to the VDU memory but provides some feedback that things are still working.

If that runs for a very long period of time, then you probably have a RAM fault and we can then concentrate on capturing that.

But you can do that yourself by buying Nivag's ROMulan RAMulator as I have stated previously.

That should rule out everything but the RAM...

Incidentally, was the keyboard PIA in or out when you took the photograph in post #597?

Yes, the voltage regulators will be hot - but very hot is not descriptive enough... Remember the voltage regulator on your monitor?!

Dave
 
daver2 said:
Incidentally, was the keyboard PIA in or out when you took the photograph in post #597?
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Not PIA and not VIA on board during this test!
Where i can buy ROMulan?? Can otherwise testing with logic probe or scope ??
 
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