I dont have any MDC option boards so I've never really looked at the menu, much less tried toconfigure anything.
I cant say if the codeplugs I did see these "random" bytes above 1FFFh were sporting any MDC settings or not.
It sound like a viable means to transport temp data to the uC to configure accessories/options that need not reside in the codeplug proper.
That discovery also means for any configuration that requires data be transported to the uC via space above 1FFFh will require the emulated codeplug to also be full size (>8k) to accomodate the feature, at least for the initial write to the radio.
Presumably the accessory/option retains that info/configuration on re-boot?
Another twist in the Saga that is X9000.......
