Is it possible to make a cartridge for the A500 through the expansion port? I am going to check my A500 book tonight to see what the memory map says. I remember how the NeoGeo had a 300 MB cartridge. I do not think it can handle that much memory anyway with out extra logic.
Well you could just stick a flash disk on a board, have it generate the chipselect from a fixed location and have some software to look at that address and load whatever is there.
Not really what I would call a cartridge system though.
Better to add an autobooting IDE card and use compact flash "cartridges" with the games on.
There are designs on Aminet for IDE cards or Zorro adaptors to use normal Zorro IDE cards.