Memory at 0xC00000..0xcfffff is autodetected by the kickstart without the need of addmem programs. It is "so-so-fast mem" refreshed by the gary suposedly, but can be implemented some other way, and has higher priority than chip mem for allocation purposes. I don't know if your fastRAM will have higher priority or similar, though. The use ?, similar to fastmem.
When you only have 1,5MB Chip mem:
The additional 1M chip mem, should be mapped to 0x08 0000 to 0x17ffff, to form a contiguos 1,5MB area. otherwise, you will have a hole between the end of the first 512k and the beggining of the 1MB.
For 2MB Chip... the extra 1MB should be mapped to 0x100000.
With that much Fast mem I don't see a need to map the extra chip at 0xC00000, more chip mem should be more advantageous.
