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New Acquisition: PET 2001-32N

CommodoreZ

CommodoreZ

Experienced Member
Joined
May 18, 2007
Messages
182
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Z Labs.
I had the fortune of acquiring a PET 2001-32N recently in functioning condition. Needless to say I'm happy to have one! However, I have plenty to learn since this is my first extensive interaction. I can enter stuff into BASIC which runs fine, but I have yet to exhaustively test it (more on why I haven't later).

pet01.jpg
Click for larger version

Seems it has a few modifications made to it, including what kinda looks like a current loop interface. My knowledge of current loops is admittedly very limited. I'm curious if anyone could clue me in about why exactly it's hooked in this way with banana clips. Keeping in mind that there's only 40 columns available, I have no idea what they would want to interface with.

It also has plenty of tape covering up the card-edge connectors, plus a pair of screws securing the chassis closed. The cosmetic wear has me guessing that this was used in a school or office where they didn't want folks to be able to open it. It has a single button installed on the front panel where the C= logo was, which brings up the text pictured on the screen in the last image. Any idea why someone install a button like that?

pet04.jpg
Click for larger version

The main thing that concerns me is the lack of responsiveness from some keys of the keyboard. A few keys like both shifts seem entirely dead (shift-lock works for the moment), and others require very hard keystrokes (or multiple presses) to produce a character on screen. Is repairing the keyboard a possibility or do I have to replace it?

One last thing: I'm trying to decide what avenue I should pursue for data storage. Obviously there are floppy disks, but I'm not familiar with which FDD models are the preferred choices -- there are so many! Plus there is the classic external dataset. But an easier place to start would be something that would let me pull software images from a modern computers. I've seen versions for later Commodore machines, but never PET/CBM era stuff.

pet12.jpg
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pet08.jpg
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Congratulation!

Most PETs were in fact used in schools. That's where I was first introduced to them; they had them in my high school.

The pushbutton puts you into the monitor, which is very handy. It asserts /NMI and the "diagnostic line" if memory serves.

As far as the current loop, the possibilities are endless.

Screws holding it shut are normal, Commodore put them there in every one.

The first thing to do with all the keys is blast compressed air between them, then repeatedly press all of them until they come to life. If that doesn't work, you will have to disassemble the keyboard. But, in my experience, it usually works.
 
CommodoreKid said:
The main thing that concerns me is the lack of responsiveness from some keys of the keyboard. A few keys like both shifts seem entirely dead (shift-lock works for the moment), and others require very hard keystrokes (or multiple presses) to produce a character on screen. Is repairing the keyboard a possibility or do I have to replace it?
Click to expand...

Well done on the PET I've got the same model. It had the same keyboard problem. I remember trying to get it to work by cleaning the contacts with an eraser...I can't recall the exact details now but I did find some instructions on the Internet somewhere. Doing this seem to improve things for a while but it always reverted. Thankfully, I was lucky enough to find a new keyboard replacement.

Anyway, good luck with it. They are cool machines!

Tez
 
Hello Tez,

It's a shame you're so far away, I might like to experiment with that stubborn keyboard. I wonder if it could be plated.

I was lucky with mine, it is the same, and also had a lot of dead or difficult keys. I blew the dust out and very repetitively worked each key. They mostly worked, with some effort still needed on some keys. Then I spent a lot of time programming the PET and after all that typing the keyboard wore in, and has been perfect since.

And, by the way, soldering wires to card edge connectors doesn't seem that out of place back then. I've run into that on other things. I reckon things were designed for connectors and then someone decided it would be cheaper to solder wires on than solder wires to a pricey connector.

Matt
 
CommodoreKid said:
But an easier place to start would be something that would let me pull software images from a modern computers.
Click to expand...

Real Commodore IEEE 488 floppy disk drives like the 4040 and 8050 are huge, overly complex and unreliable. Check out the modern micro SD card replacements:

PETDisk from bit fixer.com, and the PET microSD from either Tynemouth Sotware or Primrose. Search the web, there may be others.

While you lose a little authenticity and perhaps full PET IEEE instruction compatibility, these devices basically take no desk space and are a lot easier to interface with from the web by taking the SD chip over to your modern PC and plugging into the USB port. Right now they perform program SAVE, LOAD, Directory and some other functions. Free firmware updates in the future promise to make these devices 100% PET compatible with sequential and relative files, etc.
 
The SD card options probably are the best.

If you want to be more authentic without taking on an IEEE drive though, the Datasette is a good compromise. I haven't done it but I believe you can write Datasette K7s with a modern PC and any old cassette recorder.
 
KC9UDX said:
If you want to be more authentic without taking on an IEEE drive though, the Datasette is a good compromise.
Click to expand...

KC, you are right, if the OP just wants storage for a little 'show & tell' once in a while, a cassette deck especially a Commodore 1530/C2N would be great. They are still quite plentiful. If however he wants to use the PET to play several games and perhaps code some BASIC then, as you say, SD storage would be better.

I can not recommend an old Commodore floppy drive as the last several people on this forum that bought one have yet to make them operational. The dual CPU design using shared memory on opposite phases of the clock makes for a very difficult debug. Not to mention the analog controller board.
-Dave
 
Heyyyy... Not only did I get my 8050 running, I even got my D9060 working :)

But, I agree. I wouldn't recommend one to someone unless they are seriously dedicated or technically prepared for the almost certain repairs.
 
KC9UDX said:
Screws holding it shut are normal, Commodore put them there in every one.
Click to expand...
Double check the picture I posted -- on either side of the keyboard there are two big silver screws. Seems a bit irregular if you ask me.

KC9UDX said:
The first thing to do with all the keys is blast compressed air between them, then repeatedly press all of them until they come to life. If that doesn't work, you will have to disassemble the keyboard. But, in my experience, it usually works.
Click to expand...
Excellent, I'll give that a try first and report back.

tezza said:
I remember trying to get it to work by cleaning the contacts with an eraser...I can't recall the exact details now but I did find some instructions on the Internet somewhere.
Click to expand...
Alright then. That will be plan B.

KC9UDX said:
And, by the way, soldering wires to card edge connectors doesn't seem that out of place back then.
Click to expand...
None of the wires on mine seem to be soldered to card edge connectors. They kinda disappear under the motherboard, with a few exceptions that are soldered onto the pin headers at the rear.


As for software loading, the consensus seems to be "don't bother with disk drives". I'm glad I asked about them. The SD card option seems like a fine solution! I'll flip through the suggestions and pick one that's right for me.

I do have a 1530 C2N... somewhere in storage, inaccessible at the moment that I've used with my VIC-20's on occasion. I'd imagine it will work just as well here to get the authentic experience.
 
EPROMS in $9000 and $A000 adresses

EPROMS in $9000 and $A000 adresses

From the photo, I see two extra EPROMs in the $9000 through $AFFF address space. Try to run the code with sys 9*4096 and see what happens.
 
CommodoreKid said:
Double check the picture I posted -- on either side of the keyboard there are two big silver screws. Seems a bit irregular if you ask me.
Click to expand...

Yep, sorry, couldn't see that on my phone :)

If I had to keep care of a PET in a classroom or industrial environment, I'd do the same thing. It's essential to be able to screw down the bonnet, but, installing and removing the factory screws on the bottom is very inconvenient.
 
Regarding the use of floppies with a PET, there's another option: converting a 1541 to IEEE 488. There's some info on doing that on the net, including the Vintage computer forums. Several members discussed this option a few years ago. As I am thinking of trying it, I wonder if anyone got success with this conversion?
 
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