Wanted to let you know about a new device for your Commodore PET: The PETvet!
Basically, the PETvet replaces all of the RAM and ROM in your PET using a single SRAM chip. Different ROM images are stored in the flash memory of an Atmel microcontroller, which pre-loads the ROM contents into the right place in memory before the CPU starts running.
You can also use the PETvet to view the memory contents of a running PET by dumping the contents over a serial port. This can be useful when debugging an ailing PET motherboard. It can also be used as a basic terminal output for a PET by viewing the contents of video RAM.
The PETvet is in the final stages of testing right now and will soon be available here as a kit or as a fully assembled unit. More details to come.