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Commodore PET 2001-8 Question
- Thread starter dondi
- Start date
daver2
10k Member
That looks right for running EVERYTHING from the PET.
Go back to the PETTESTER and check the checksum that is reported (change ROM Enable E from OFF to ON).
Dave
Go back to the PETTESTER and check the checksum that is reported (change ROM Enable E from OFF to ON).
Dave
dondi
Experienced Member
daver2
10k Member
It seems to have now gone back to what it was before (if memory serves me correctly).
What I can do (it will have to be tomorrow now) is to download the image files for the two (2) Kernal ROMs in your machine and calculate the checksum for what they should be. If they are the same as in my PETTESTER manual, we know that one (or both) are duff.
I see you have an interesting 'B' ROM checksum now - or is that still changing randomly?
I am out training people to use our new digital audio mixer desk at Church tonight - so I have to finish off my 'real' work for the day yet...
Dave
What I can do (it will have to be tomorrow now) is to download the image files for the two (2) Kernal ROMs in your machine and calculate the checksum for what they should be. If they are the same as in my PETTESTER manual, we know that one (or both) are duff.
I see you have an interesting 'B' ROM checksum now - or is that still changing randomly?
I am out training people to use our new digital audio mixer desk at Church tonight - so I have to finish off my 'real' work for the day yet...
Dave
dondi
Experienced Member
B ROM checksum changes constantly.
Just a reminder that the 6520 in B8 is still removed. Not sure if that matters.
Just a reminder that the 6520 in B8 is still removed. Not sure if that matters.
daver2
10k Member
Nope - the 6520 in B8 is for the IEEE488 bus. We are not using that at the moment.
My PETTESTER is only driving the ROMs and the keyboard 6520 at this stage of the test. Of course, it is using the low 512 bytes of main RAM and the screen as well - but these were tested previously as part of tests that ran fine.
Dave
My PETTESTER is only driving the ROMs and the keyboard 6520 at this stage of the test. Of course, it is using the low 512 bytes of main RAM and the screen as well - but these were tested previously as part of tests that ran fine.
Dave
dondi
Experienced Member
daver2
10k Member
Be careful. These devices are masked programmed ROMs - so despite the fact that they are identified as a 6540 - it may not contain the same program as you want! The other numbers on the chip tell us what is stored into the ROM itself!
You can't change the device either. The 6540 devices are ROMs, not EPROMs or EEPROMs - so not erasable or programmable.
Dave
You can't change the device either. The 6540 devices are ROMs, not EPROMs or EEPROMs - so not erasable or programmable.
Dave
dondi
Experienced Member
Ok thanks!
dave_m
Veteran Member
That top ROM is stamped 6540-014 and is from a BASIC 1 set and the chip goes into socket H6. Here is the info on that part:
H6 901439-06 6540-014 ROM Basic 1 D800-DFFF
And note that there are no way to know that this 45 year old part is still working unless it was recently tested.
daver2
10k Member
dondi
Experienced Member
Thank you for the data dave_m
dondi
Experienced Member
I took the time to mend a fence on my property. It never goes as easy as you think it will!
daver2
10k Member
Ok, I have found the files I need.
I will have a look at them tomorrow now I think.
I have a fence to replace - but I am going to get some 'men' in...
Dave
I will have a look at them tomorrow now I think.
I have a fence to replace - but I am going to get some 'men' in...
Dave
daver2
10k Member
Right. So an interesting afternoon fighting with PET ROMs and checksums... I will have to include an expanded section in the V5 manual...
The 'C' ROM checksum of CCC9 indicates that your ROM set is actually BASIC2. Basically BASIC1 with a working IEEE488 port!
However, on none of the checksums do I get what you have for ROM 'F'.
What I would suggest next (as Nivag has already proposed) is to setup the RAMulator board to run the VOSSI tester. Nivag has pointed you at the PDF file to do this, but I have included it here for convenience if you don't like reading!
RAM link OFF, EAzy link OFF.
ROM Enable links = OFF OFF OFF ON.
ROM Bank links = OFF OFF OFF ON.
This should run the VOSSI test ROM on power-up. It still won't test your F0 and F8 ROMs but it will test the rest (including the EDIT ROM).
Let's see what that does for us.
After that, we will try and run your ROMs - but with the 'F' ROMs emulated by the RAMulator. But leave that for now until we get the VOSSI results in.
Dave
The 'C' ROM checksum of CCC9 indicates that your ROM set is actually BASIC2. Basically BASIC1 with a working IEEE488 port!
However, on none of the checksums do I get what you have for ROM 'F'.
What I would suggest next (as Nivag has already proposed) is to setup the RAMulator board to run the VOSSI tester. Nivag has pointed you at the PDF file to do this, but I have included it here for convenience if you don't like reading!
RAM link OFF, EAzy link OFF.
ROM Enable links = OFF OFF OFF ON.
ROM Bank links = OFF OFF OFF ON.
This should run the VOSSI test ROM on power-up. It still won't test your F0 and F8 ROMs but it will test the rest (including the EDIT ROM).
Let's see what that does for us.
After that, we will try and run your ROMs - but with the 'F' ROMs emulated by the RAMulator. But leave that for now until we get the VOSSI results in.
Dave
dondi
Experienced Member
daver2
10k Member
That looks OK as well. It is giving the ROMs a clean bill of health.
Ignore the H4 being OK message - as this is testing Nivag's code rather than the 'real' ROM.
Also, ignore the IEEE488 errors. I assume the 6520 is still missing!
What I suggest now is mapping Nivag's BASIC 2 kernal ROM in and seeing if we can get BASIC to run (again).
To do that I think you set Nivag's links as follows:
ROM Enable F to ON - all others OFF.
Select bank 3 ROM by setting the links to OFF OFF ON ON.
Dave
Ignore the H4 being OK message - as this is testing Nivag's code rather than the 'real' ROM.
Also, ignore the IEEE488 errors. I assume the 6520 is still missing!
What I suggest now is mapping Nivag's BASIC 2 kernal ROM in and seeing if we can get BASIC to run (again).
To do that I think you set Nivag's links as follows:
ROM Enable F to ON - all others OFF.
Select bank 3 ROM by setting the links to OFF OFF ON ON.
Dave
dondi
Experienced Member
daver2
10k Member
Oh well, that's rubbish isn't it!
It clearly isn't random, so the CPU is trying to clearly do something...
Let's run the entire ROM set out of Nivag's board by setting ROM Enable CD and E from OFF to ON as well as leaving F ON.
Dave
It clearly isn't random, so the CPU is trying to clearly do something...
Let's run the entire ROM set out of Nivag's board by setting ROM Enable CD and E from OFF to ON as well as leaving F ON.
Dave
