FWIW, if you have the 64K - 256K board it can be very easily rigged to be a 640K board. That might free up Slot 5.
I ran into that information while looking up the memory map information. I'd like to keep using the 1MB RAM Card because it should allow me to use free 64K blocks of high memory for loading TSRs into high RAM. I have one free 64K block at B0000 and I'm trying to free up another.
...I don't have to mod my motherboard to get 640K...
It's not much of a mod -- one jumper on a pad that's already there and adding a chip to a socket that's, also, already there. Sounds to me like Big Blue was just beggin' ya' to do it to their board.
It certainly does sound like Big Blue wanted you to mod it if it's that easy! I just may have to try it. i