It's basically an option ROM but contains 8 different images. The first is a menu selection pick which ROM you want active and the other 7 are normal option ROMs. The menu selection ROM also has ram tests, video test cards and a JiffyDOS selection that allows you to turn off and on older "Switched" JiffyDOS installs by replacing the toggle switch with a wire from this board.
It remember state through power down so no re-selecting the ROM every time you turn it on, it stays as you left it.
That sounds really cool (and no rule violations I see). But can you explain how it remembers the state after power-down? Sure I/we can follow the link if bored (time to kill), but if you can write a little more detail we would appreciate it!
Following your link I didn't find much more detail (perhaps I missed something?) I did see that you are "Out of Stock" which (I presume) means business is good?! Always nice to see a fellow Commie succeed!
Anyway, Happy New Year and thanks for sharing your "C128 Multi-ROM" with us!
It's artificially out of stock while I try and make the installation idiot proof. We are waiting for new cable clips that can easily be attached to the pin of U3 (existing ones suck).
It stores the state in eeprom contained inside the PIC micro controller that actually does the rom selection. When you set menu options data data is actually written to an unused memory address that is decoded by U3 inside the 128, the PIC sees that and saves it.