There are lots of cards for various systems with bankswitched ROMs, EEPROMs, and Flash ROMs. None of them demand-load from disk - how big are these ROMs?
In the case of the Nimbus they are I believe up to 256K, and are essentially disk images on ROM.
In the case of the Dragon they could be anywhere in the region of 16K-1024K
Doing the bank switching is not my issue here, I've done that before.
What I absolutely *DONT* want is to have to specify the ROM in the source file. The end user should be able to specify it.
I'll take a look at the examples people have given. It also strikes me that the QL ROM cartridges may also be worth looking at.