It’s the kind with the “Fat 40” universal 40/80-column motherboard. There is a fellow on one of the PET sites who sells new-old-stock official Commodore-branded 64K RAM upgrades that will work on this model, but they appear to preclude other modifications within the case due to being physically enormous. (I am particularly taken with the idea of the internal IDE modification I’ve heard rumours of, but there are others possible.) Also, I’m not at all sure I could afford to pay for such a beast; with shipping and so on, they are quite expensive by my standards.

Does anyone have any pointers to documentation on using the 100 expansion header pins at the back right of the motherboard? I know from the 8296 documents I’ve examined that 50 of them are just ground-plane pairs, but I lack detailed explanation (and reliable identification) of the 50 actual signal pins. I haven’t even seen a reliable indication of what kind of female connector you would use to plug onto the two 50-pin headers!

Hoping someone’s gone this route before me,
gsteemso

Quote from: gsteemso on October 15, 2009, 02:33 PM
It’s the kind with the “Fat 40” universal 40/80-column motherboard. There is a fellow on one of the PET sites who sells new-old-stock official Commodore-branded 64K RAM upgrades that will work on this model...

Where is that site?
     FWIW, at the Sept. 12-13 Vintage Computer Festival East 6.0, there was a PET 64K RAM upgrade (or was it 32K) being sold on the consignment table.  I don't think it sold.  If you want to buy it, you'd have to contact MARCH (Mid-Atlantic Retro Computer Hobbyists).

QuoteDoes anyone have any pointers to documentation on using the 100 expansion header pins at the back right of the motherboard? I know from the 8296 documents I’ve examined that 50 of them are just ground-plane pairs, but I lack detailed explanation (and reliable identification) of the 50 actual signal pins. I haven’t even seen a reliable indication of what kind of female connector you would use to plug onto the two 50-pin headers!

PET gurus, Larry Anderson or Bill Degnan, could help you on that.  If you don't know their e-mail addresses, I could tell you.

                AmiWest Show on October 16-18,
                Robert Bernardo
                Fresno Commodore User Group
                http://videocam.net.au/fcug

I’ve already been in touch with Bill Degnan â€" he’s the one with the upgrade kits, of which he only has one left for sale â€" but I haven't tried mailing Larry yet. I’ll try him today.

Thanks for the tip about MARCH,
Gordon

PET pinouts are here:

http://www.6502.org/users/andre/petindex/pinouts.html

A closer look reveals that those are all from the 8296, not the earlier 8032 family which used a different board. There is a difference table, but it's abbreviated and does not explain what the signals are used for.

http://freenet-homepage.de/x1541/hardware/petram.html

Quote from: Dragos on December 16, 2009, 03:45 PM
http://freenet-homepage.de/x1541/hardware/petram.html

Yes PETRAM works fine for 4008 to 4032.

PETRAM works also fine to extend floppy drives. Good for broken Dolphin DOS and other Speeder.