CPU memory map

Virtual address space
The zero page, stack, and vectors exist at fixed locations within the virtual address space. The physical memory backing these can be swapped to any bank at any time, but the virtual addresses cannot be changed. The rest of the virtual address space has no special meaning to the hardware.

Physical address space
The physical address space varies by console type.

Note that a PC Engine CD can be connected to the SuperGrafx as well - created a layout in which both the PC Engine CD's 64 KiB of additional RAM and the SuperGrafx's 24 KiB of additional RAM are available.

PC Engine
Any unmapped address in physical memory can potentially be mapped by an expansion port device or a HuCard, but most HuCards lack any sort of memory mapper and simply use the highest address bit as a chip enable.

PC Engine CD
TODO: Do any mirrors exist?