Part 6: Address space and preliminary emulation.
Since the 6809 interrupt vectors needs to be in the last bytes of the 64KiB address space, it is the first thing you will look at:
4011? that means the ROM is mapped/banked in a few places?
Mirroring the rom in [C000:FFFF] (so that the IRQ vectors are in their right spot) as well as [4000:7FFF] seems to make it boot, but it hangs waiting for bit 6 to be up on $F892 .. this of course means the ROM is not 'seen' in that memory spot (a ROM offset cannot change itself, so this code would not work)...