Looking for help with a Commodore Pet 2001

[daver2]

Yes and no - your choice...

F04 fits into the Kernal ROM socket (H7) (and doesn't require the Kernal ROM to be operational).

V04 fits into the EDIT ROM socket (H3) (but does require the Kernal ROM to be partially operational).

Possibly the F04 is better (if you have the choice).

Dave

 

[rglenn]

Thanks.

 

[Jannie]

Have you tried running my PETTESTER firmware?

This makes diagnosis of a PET somewhat easier...

You can't (unfortunately) just burn an EPROM for the 2001 without an adapter. If you have one of the ROMulators, some of these are equipped with my PETTESTER and will work in a 2001.

Dave

A trick that can help for people who can't program old EPROMS, is to write PETTESTER to a 28C16 EEPROM. For me it worked, so far, on all the different boards I've repaired.

 

[Nivag Swerdna]

@daver2 Is V5 ready? 2K Checksums would be nice here!

 

[daver2]

Too busy at work I am afraid at the moment... Have been for a while...

Dave

 

[Nivag Swerdna]

Well I should have warmed up the soldering iron so I could put @rglenn 's ROM in the post but I couldn't resist a small hack of the PETTESTER source...


ROM Top line is original sums... next line should be a sum of only the first 2K... in the E case they match since only 2K of E is summed first time around. I'm sure it could be made prettier.

 

[Nivag Swerdna]

On my way to the post box.

 

[rglenn]

I received the PETTESTER v4 IC today and placed it in H3. I have a Tynemouth Software Mini PET ROM/RAM board installed so I booted it with the ROM/RAM board enabled and again with it disabled.
The first pic is with it disabled and the 2nd enabled. The screens never change - or at least not within a minute.

 

[daver2]

I thought we went for the F04 version - which should fit in socket H7 and not H3?

That's where Nivag has placed his circle...

Dave

 

[rglenn]

I ordered the v4 right before your response of ------ "Possibly the F04 is better (if you have the choice)".
Do the screens indicate anything? Will I need to order the v2 PETTESTER?

 

[daver2]

I would try H7 socket anyhow - on the off-chance that is what Nivag has sent you.

The first picture indicates the usual random screen, so no code is running at all.

The second screen sort of looks like a crashed TIM (debug monitor) screen.

None of these are the PETTESTER running...

Dave

 

[rglenn]

Put it in H7, looks like your guess was right, he sent me the other version. I'll need to read your user guide to see if I can make any sense of the screens.

 

[rglenn]

I think this is the end of the test. I have 2 questions -

Does the 04K DRAM Memory test mean it only sees 4k of memory (pic1)?
If I enable the Tynemouth Software Mini PET ROM/RAM it bypasses the ROM/RAM on the system board of course including the diagnostic ROM (pic2). Any thoughts on what is causing the random characters in both pics?

 

[daver2]

Yes, it is something in the video display circuitry somewhere.

The VDU VRAM test has been given a clean bill of health, but the video addressing or video data latch could be faulty somewhere.

Let me get the schematics out this afternoon and hive you some pointers.

Yes, it is only seeing 4K of (working) RAM.

Dave

 

[Nivag Swerdna]

Hi. I did do a bit of poetic licence and sent you the version that goes in H7. It should say put in H7 on the label

Can you remove the Tynemouth board, just put it in H7 and have a 6502 in the CPU socket.

And send a photo of what you have set up.

It really shouldn't look like what you are seeing and I'm confident the tester worked a week ago!

PS
We can convert it to the other version with some solder jumper swapping later if that is required.

PPS
There are some encouraging numbers on the screen (along with all the garbage).... F21C is 901439-04 and EC6C indicates that PETESTE2KF04 is correctly being read... F21C+FA50=EC6C
Also... CA92 indicates a good edit ROM... edit-1-n.901429-03.bin, 31FC indicates 901439-02... some of the other numbers are less convincing.

 

[daver2]

I posted my response in the wrong thread. Let's start again...

Are video RAM devices C3 and C4 socketted? I must admit, I am suspecting that video RAM device C3 could be faulty - but this is not the only explanation...

Would it be possible to get a short video of the initial power-on screen when PETTESTER runs the video RAM test?

You might have to fit a reset button (a 100 Ohm resistor in series with a normally open pushbutton - or a switch) fitted across capacitor C6. This is the capacitor close to the 8-pin 555 timer IC.

Dave

 

[rglenn]

C3 and C4 are socketed. Based on your suspicion I replaced C3 with another 6550 (I had to try a couple until one worked), but the random characters are gone with and without the Tynemouth Software Mini PET ROM/RAM enabled.

Awesome and many thanks for all the help! I think I still have a video issue. I'll try to post a short video of what I see when running a PRINT "HELLO WORLD" program.

 

[rglenn]

Can't upload video so I grabbed a couple pics. basically it is running and displaying the line in groups of lines rather than in continuous lines as expected.

 

[daver2]

>>> Awesome and many thanks for all the help!

No problem. A team effort.

I think what you will find is that this is normal with a standard 2001. This was 'fixed' in later models.

You will need to post a video elsewhere and link to it.

Next to check is the IEEE 488 port. Which 'version' of BASIC do you have in the ROMs? You will need to run PETTESTER and post the checksums (or at least ones we can now read correctly) - unless we have already identified these from the ROM numbers previously...

Do you have a cassette unit?

Dave

 

[rglenn]

It does have a cassette unit but it isn't working. Nothing moves regardless of key pressed FF RW PLAY etc....

I'll plan to take a look at it shortly and run the PETTESTER again and post the checksums.

I believe I have BASIC v2 based on the start up screen - but I'm not sure.

*** COMMODORE BASIC ***​