The Commodore 64 was very flexible in terms of how RAM could be controlled. ROMs and I/O devices could easily be swapped out by setting bits in the first two addresses of memory. The VIC-20's ROMs and I/O devices seem to be hardwired to certain addresses, and can't be disabled.
Was there any sort of bank-switching(?) RAM expansion that enabled the VIC-20 to break the 40 KiB Barrier?
(40 KiB is whats let of the address space after ROM and I/O)
I'm not looking for any modern development, but contemporary expansions (i-e- of the 1980s. Of course everything with more than 64 KiB is as wellcome.