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> The UT69R000 [has] a 64K data space and a 1M address space.

So the virtual address space is 1M but it can only physically interface with 64K of memory?

The chip itself can have up to 64k Flash (and another 64k of RAM). But the CPU accesses the memory via a MMU that can map the 1M address space into (mostly) 64k chunks. So effectively the OS can use 1M physical addresses and the CPU itself uses close to 64k of them (depending on how you configure the MMU).

edit: so the whole address space of 1M can be mapped via the MMU into 64k installments.

Pretty similar to many CPUs of that era. x86 included.

https://en.wikipedia.org/wiki/X86_memory_segmentation

And the many mappers NES and other consoles used: https://www.nesdev.org/wiki/Mapper

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