This is a tested and working project

This adapter is intended for replacing the original 2332 BASIC and Kernal ROM with a 2732 EPROM in the Commodore PET / CBM computers (i.e. 3032, 4032, 8032, 8032-SX, etc.).

Note: it could work also in other environments, but it was tested for the above case only.

Note: it doesn't work with PET 2001 - 4k / 8k with 6540 ROMs. Use my other adapter for 6540 ROMs instead: https://www.pcbway.com/project/shareproject/Replacement_for_Commodore_6540_ROMs_PET_2001_early_version_ee077568.html

Build instructions:

The adapter is really easy to build and doesn't require any configuration.

The needed parts are just a 24 pin DIL socket (large profile) and 2x 12 pins male headers (I strongly recommend the small, round pins header that doesn't hurt the original PET socket).

it's a good idea to use another socket (it will be called "second socket" in the following instructions) to keep the two headers aligned. It's just a suggestion because it will be a little easier to solder the socket, but you don't really need to use it if you don't want.



Just insert the headers in the second socket, leaving the shorter side of the pins exposed

(if you don't want to use a second socket, simply use the socket that will be later soldered on the PCB).

Insert the two headers in the PCB, using this picture as reference.

To make easier to solder the socket (next picture), just solder one of the two headers - See picture. (if you are not using a second socket for alignment purpose, solder both headers now)

Now remove the second socket; one of the two headers (the soldered one) will remain in the PCB while the other will be extracted with the second socket.

Insert the socket (remember to correctly align the socket notch with the PCB label) and solder all the socket pins

(if you are using the second socket and you didn't solder the one of the two headers, it should be a little bit easier to solder the inner line).

Now insert again the second header (that should be still inserted in the second socket) and solder it (forget this step if you already soldered both header at the previous step).

Remove the second socket (if you used it) and you're done!

How to use the adapter:

Program a 2732 EPROM with the correct image. It must be a 4kilobyte (32 kilobit) image.

The Commodore PET images can be found at the following page:

http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/pet/index.html

(Thanks to Bo Zimmerman for his great site!)

Remove the broken ROM from your PET, put the programmed EPROM in the adapter and then put the adapter in the ROM socket.

Note: EDIT ROM and Character ROM are 2kilobyte (16kilobit) and requires a 2716 EPROM that can be inserted into the ROM socket without any adapter. You can also use a 2332 EPROM without adapter, but since it's twice the size of the image ROM, the easiest way to proceed is to copy twice the image in a new file. You can easily do that from a shell DOS, using the DOS command:

COPY characters-2.901447-10.bin /b + characters-2.901447-10.bin /b characters-2.901447-10-for-2332.bin

(replace the "characters-2.901447-10.bin" name with the right image you want to use)

Two different PET models using the EPROM adapter.

The adapter installed into a CBM 3032 (PET 2001/32) model

Two adapters in a 8032 model (and the 2716 EPROM without any adapter that replaces the 2 kilobyte EDIT ROM).



Troubleshooting:

In case the adapter doesn't work, verify all the solders, be sure you used the right EPROM image (it should match with the ROM Label) and you inserted it in the right socket.

If everything is fine, replace the original socket on the PET board. The Commodore socket of that era are notorious to fail. I solved many problems on my PETs simply replacing the sockets!