The original KIM-1 computer only came with around 1K RAM and 2K of ROM, my RC-ONE is a functional replica and because of it also shares those specifications. If you inspect the chips used you may however find that the computer actually has 32K of static memory instead since those chips are a lot cheaper to buy these days, so I somewhat cheated and just gave you access to the original amount.

The reasoning for this is that the memory space is mirrored in the original design for every 8K block of address space, we need to replace the address decoding used on the board so that we can access the entire 65K memory space and the original service manual actually have a chapter dedicated to explaining how this can be added to the computer. The 65K Expansion is my implementation of those features, except of course that you'll have access to a lot more memory.

If you want to use your RC-ONE with more than the more basic expansions, but also want access to most of the expansions created specifically for the system (as well as quite a few RC6502 expansions) then you will need this expansion as well as a suitable backplane.