I made a couple of attempts to connect to a telnet BBS using tcpser and Novaterm. I failed for some reason even if the connection between tcpser and Novaterm is 'working', as in characters can be transferred both ways. I read about problems with the carrier signal and since I won't be making a special cable I could appreciate a Wifi-solution that works out of the box.
Ok, so it opens a TCP port and communicates through that. It will be a bit more difficult to set that up since it requires a host address to connect to. My serial setup currently doesn't require anything to be configured on the C128 side so I'll have to think about that.
$d506 controls the *size* of the shared memory areas and *if* there should be any sharing at bottom or top memory. Sharing enables RAM 0 access regardless if RAM 1 is enabled. So you can just turn off the bottom and top sharing and enable RAM 1 to get only RAM 1 whenever RAM is accessed. So bit 2-3 of $d506 is what needs to be changed as well as the bank selection in $ff00.
RAM can be shadowed by ROM of course, but that's a different problem.
e5frog built cartridges based on the Magic Desk design in order to sell them. He gave one to me so I didn't have to build one myself. I do have the Easyflash cartridge as well but it is a bit more fancy with a custom built one.