The A1200 version can comfortably handle upto 2GB FastRAM.
The Amiga memory map is full of reserved areas, you can never see 2GB of FastRAM.
But that’s a 32bit system. I’m guessing the A500 and being a 16BIT system has a lower ceiling limit for RAM.
The 68EC020 of the A1200 has exact same address space as 68000, and it is 24bit, which is why the RAM limitations on stock A1200 and stock A500/A600 are exactly the same, 8MB Fast + 1.8MB ranger and 2MB chip (given cool enough agnus on ECS systems).
Anyways, with CPU upgrades, this limit vanishes, though exactly how far you can go will depend on hardware configuration, as I mentioned, Amiga memory map is full of reserved areas for dedicated use. The number 1792MB occurs to me, but I suspect that is the full zorro III address space.
