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PET 4016 Upgrade options?

WimWalther

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My PET 4016 has spent most of the last 25 years holding down a shelving unit in my storeroom. I figure that it's time I gave it some love, after being so very long ignored.

Soo.. what's to be done with it?

What are the upgrade possibilities - more RAM, later / enhanced ROMs, maybe adding a speaker or other noisemaker (does it have one already)? What are the options for loading software - about all I have available right now is a VIC-20 Datasette, which I think will work with it.

Your thoughts?
 

daver2

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Depending upon what you have got, you MAY be able to update the RAM and ROM depending upon what Commodore have done.

The ROMs may be soldered in, which would make exchanging them for a later version of BASIC more troublesome.

Commodore also had a nasty habit of drilling holes in the PCB to stop people from upgrading the RAM themselves.

I suppose the best thing is to “open the hood” and post a photograph of the main logic board.

Depending upon the version of BASIC, I would be tempted to add a SD2PET adapter rather than a cassette. That would be my advice as a starter-for-ten at least.

Dave
 

WimWalther

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Thanks, Dave. Do you happen to have any pics of a drilled board? So I take it that some boards had unpopulated IC patterns that CBM destroyed to prevent their use? Can't really blame them, that was an extremely competitive market in those days.
 

daver2

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Thanks, Dave. Do you happen to have any pics of a drilled board? So I take it that some boards had unpopulated IC patterns that CBM destroyed to prevent their use? Can't really blame them, that was an extremely competitive market in those days.


Yes, you can use Nivag’s CPU card to upgrade the RAM and ROM. A good idea if the ROMs are soldered and/or the RAMs drilled. Good suggestion Robert.

Dave
 

Eudimorphodon

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A 4016 should already have BASIC 4.0 so there’s not a ton of reasons to upgrade the ROMs.

The stock RAM is almost always soldered in Dynamic boards. How difficult going to 32k will be depends a lot on what the RAM config in there is. It’s *probably* one bank of 16kbit (4116) drams, but the service manual has jumper pad configs documented for an alternative of two banks of 4108s. (I would guess the latter is rare and they only used 4108s on the 8k sku, but Commodore is always unpredictable.) If it’s one bank of 16k and they didn’t sabotage the board you should be able to turn it into a 4032 just by adding the missing parts and changing the solder jumpers.
 

Eudimorphodon

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Thanks, Dave. Do you happen to have any pics of a drilled board? So I take it that some boards had unpopulated IC patterns that CBM destroyed to prevent their use? Can't really blame them, that was an extremely competitive market in those days.

I'm pretty sure I posted a picture of my drilled board at some point, but it doesn't look like the new forum software has the "gallery of attachments you've posted" feature of the old software (?) so I can't find it. But trust me, it'll be obvious if your board is drilled. There will be a couple holes about the diameter of a pencil obliterating some traces and IC pads in the area of the board where the unpopulated memory chip footprints live. If you have unpopulated footprints *without* big obvious holes then fully populating the board may be a legit option.
 

Hutch

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Unless it's a very early 4016 with the 9" screen, it's likely a universal board and AFAIK, those were never drilled out since that would damage other things.
The banks are 2x16K so there's probably one bank populated and the other empty making it simple to add the missing ram chips.

As far as the ROMs, the 4016 will have 4.0 ROMs at least. Though there is a 4.1 version there's no real need to upgrade. AFAIK, the differences are minor.

You can buy a Tynemouth RAM/ROM board or a Romulator, both of which will max out the RAM and give you the option of switching to any ROM version you want.
Probably the best "upgrade" available and very helpful if you're troubleshooting problems.
 
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WimWalther

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Good info here, thanks to everyone posting.

So really, it seems that the only potentially useful move is to upgrade the RAM to 32K by way of populating the empty patterns on the board. So I'll assume it's as simple as obtaining more chips of the same type / speed as already found on the board?
 

daver2

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Post a photograph and we will all know for sure.

You may need to adjust a link or two as well. This is why a photograph will be useful - to help us identify exactly which 'flavour' of PET logic board you have.

Dave
 

Eudimorphodon

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Unless it's a very early 4016 with the 9" screen, it's likely a universal board and AFAIK, those were never drilled out since that would damage other things.

I was assuming it was a 9” model because the OP asked about a speaker/noisemaker. 12” models with Universal boards have the little buzzer that goes “chirpchirpchirp” at startup, 9” don’t.
 

Hutch

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I was assuming it was a 9” model because the OP asked about a speaker/noisemaker. 12” models with Universal boards have the little buzzer that goes “chirpchirpchirp” at startup, 9” don’t.
Of course. I missed that. The PCB in those are the same as the 2001-N, only the ROMs are upgraded.
If it doesn't have a built in speaker, I recommend the "Stupid PET Tricks" cartridge.
Here's a photo of a board that has been drilled out and upgraded anyway.
1656451177634.png
 

Eudimorphodon

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Another alternative would be to do a piggyback job over the other bank, but that's a bit ugly.

The exact location of the holes seems to vary between these drilled boards. I want to say that on the drilled one I have there's like two holes in the actual memory chip area and a third hole off to the side severing some of the traces going to the bank at large, but I guess without getting the thing off a high shelf and looking at it again I can't confirm that fuzzy memory.
 

WimWalther

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Nah, if the stock machines have BASIC 4.0 or better, thats fine. No need yo mess with ROMs. It's going to be a RAM upgrade, if anything.
 

Hutch

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Thanks, Dave. Do you happen to have any pics of a drilled board? So I take it that some boards had unpopulated IC patterns that CBM destroyed to prevent their use? Can't really blame them, that was an extremely competitive market in those days.
Here's a better pic of a drilled out board.1656472715694.png
 

WimWalther

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Here's a better pic of a drilled out board.
Thanks, that is a better pic, or at least a more-drilled board.

As noted above, it really doesnt seem too challenging to handwire around the drillings. If my board has been so abused, that's very likely the route I will take. Don't think I have any Kynar, though.. but the 28ga stuff from old Bell System 25-pair cable should be fine.

ETA: Frustration! There aren't any unpopulated patterns on the board, drilled or not. So it looks like I'm limited to a piggyback hack (ugly, I agree) unless I want to buy a 3rd party upgrade board. So that kinda sucks.. and is likely why I've never done anything with it previously.
 
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Hutch

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ETA: Frustration! There aren't any unpopulated patterns on the board, drilled or not. So it looks like I'm limited to a piggyback hack (ugly, I agree) unless I want to buy a 3rd party upgrade board. So that kinda sucks.. and is likely why I've never done anything with it previously.
OK, that confirms it's an early 40xx with a 2001-N mainboard.

There are jumpers on the board to set what type of RAM chips are being used and how many.
You can have two rows of 16K or two rows of 8K. I guess you got two rows of 8K.
You can change the jumpers and replace all the chips, or go with a Tynemouth or Romulator option.

Jumper settings are in the schematics here.
 
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