The Amiga 2000 has a 8MB expansion-range for memory and some IO-space which can be addressed with 64k max per card.
The bridgeboard (2088,2286,2386) all have 128k of shared memory which won't fit into the IO-space and is therefore configured in the area for memory-expansions.
This area can only be configured in blocks of 2MB, so you only have 6MB left.
A potential GFX-board (on the Amiga-side) will also take 2 or 4 MB.
If you only got the 8MB expansion and the bridgeboard you need to remove 2MB from the memory-expansion.
The memory on 030-turbo-boards is normally configured outside the 68000-address-space (except for C='s 2630 offcourse evil: ) and should therefor have no effect on Z2-expansions.
