So I found a developer prototype C128...

papa_november · November 04, 2009, 05:01 PM

A few months ago, I was given a hideously beat-up C128. Upon closer inspection, it had a printed serial number sticker instead of the regular sticker on the bottom, and another sticker that said that the machine was not yet FCC approved. The motherboard looks almost like a production motherboard but has slight differences.

Thanks to Robert Bernardo, I got official confirmation from Dave Haynie at this year's CommVex that this machine was in fact a developer prototype, presumably sent out to software houses in advance of the C128's launch so that there would be software ready for it when it arrived on store shelves. He even signed the case! That was nice of him.

Anyway, the machine wouldn't boot with the original motherboard installed, so instead of trying to fix it myself, I opted to replace it entirely. The machine is all cleaned up now and running perfectly.

I'll try and get some pictures later, but I'm wondering- is this machine worth much more than a production Commodore 128? I mean, it's probably worth less than it would have been had the original motherboard worked, but I figure this way it's still useable, if nothing else.

RobertB · November 04, 2009, 05:24 PM

Quote from: papa_november on November 04, 2009, 05:01 PMThe motherboard looks almost like a production motherboard but has slight differences.

Other than the ceramic chips I remembered it having, were there other slight differences, like extra wires soldered from one point to another on the board?

QuoteAnyway, the machine wouldn't boot with the original motherboard installed, so instead of trying to fix it myself...

You know that Ray Carlsen could have tried to repair the original motherboard.

Quote...I opted to replace it entirely. The machine is all cleaned up now and running perfectly.

O.K., you put in a replacement board, but did you put the original ceramic chips that were in the developer's board onto the replacement board? I hope you kept the original board for reference.

QuoteI'll try and get some pictures later, but I'm wondering- is this machine worth much more than a production Commodore 128?

To a collector, yes, more, but I'm not sure if it is much more.

QuoteI mean, it's probably worth less than it would have been had the original motherboard worked...

Very true.

Quote...but I figure this way it's still useable, if nothing else.

There's the dilemma... whether to keep it original and non-working or to have it less original but fully working.

I still say that Ray could have worked
on that original board,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug
The Other Group of Amigoids
http://www.calweb.com/~rabel1/
Southern California Commodore & Amiga Network
http://www.sccaners.org

papa_november · November 05, 2009, 09:17 AM

Quote from: RobertB on November 04, 2009, 05:24 PM
Other than the ceramic chips I remembered it having, were there other slight differences, like extra wires soldered from one point to another on the board?

There was one wire going from one pin of the PLA chip, but the other end was detached from wherever it was supposed to be. I have no idea what this wire might be for; it could be that the machine will not boot without it.

QuoteYou know that Ray Carlsen could have tried to repair the original motherboard.

I need to ask him about it sometime. He might have seen something like the board I've got before.

QuoteO.K., you put in a replacement board, but did you put the original ceramic chips that were in the developer's board onto the replacement board? I hope you kept the original board for reference.

I suspect that at least one of the chips could have failed; the PLA seems to get fairly warm fairly quickly, as does the Kernal ROM. I might have a spare Kernal floating around, so I'll try that next. The only reason I haven't tried swapping chips yet is because I'm a bit nervous that I might somehow mess up the production board or make the prototype worse(that and I haven't had much time to work on the machine lately).

RobertB · November 05, 2009, 09:30 AM

Quote from: papa_november on November 05, 2009, 09:17 AMThe only reason I haven't tried swapping chips yet is because I'm a bit nervous that I might somehow mess up the production board...

Heh, there are always more boards and full C128s in FCUG storage.

Truly,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug
The Other Group of Amigoids
http://www.calweb.com/~rabel1/
Southern California Commodore & Amiga Network
http://www.sccaners.org

papa_november · November 08, 2009, 12:47 PM

Well, it turns out that most of the important chips on the production board aren't socketed.

I really don't want to bother with this much anymore. I just have too much other stuff I need to work on.

papa_november · November 08, 2009, 01:35 PM

Here's the best photos I could take of the board. (I'd scan it, but it's way too big for my scanner and stitching multiple scans of something like this together is a nightmare.)

Also, here's a photo of the machine, and a picture of the stickers on the back:

RobertB · November 08, 2009, 06:57 PM

Quote from: papa_november on November 08, 2009, 12:47 PMI really don't want to bother with this much anymore. I just have too much other stuff I need to work on.

Well, if you want me to bring the original board to Ray Carlsen when I see him next March, just give me the word.

He can work on it,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug
The Other Group of Amigoids
http://www.calweb.com/~rabel1/
Southern California Commodore & Amiga Network
http://www.sccaners.org

papa_november · November 09, 2009, 06:08 AM

That's ok. Thanks for the offer, though.

In the end I decided to just go ahead and eBay it anyway. I really need the money, and it's not like having it work with the original motherboard is that big a priority when the case is so beat-up. The keyboard alone needed hours of work as when I finally booted it up, nearly every key had to have it's plunger contacts replaced because I practically had to stand on it to get it to register.

RobertB · November 09, 2009, 06:22 AM

I hope whoever wins it will appreciate the developer's board.

Truly,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug
The Other Group of Amigoids
http://www.calweb.com/~rabel1/
Southern California Commodore & Amiga Network
http://www.sccaners.org