I can prepare ROMs for all vintage computers. Please contact me fro you needs.
I can prepare EPROMs for Commodore 64, 128, 128D, 1541, 1514C, 1541-II, 1571, PET CBM series and others ...
The EPROM can store the original firmware or third part firmware.
It's also possible to prepare dual kernal rom that contain the original kernal and a 3rd part kernal like (Exos, SpeedDos, others). The kernal image is selectable with a switch.
I can provide the kit for replacing the original ROM with an EPROM.
It's necessary to add a socket and a couple of diodes and one resistor.
For more info please ask me: firstname.lastname@example.org