After spending time with the eZ80, I have to say most of your complaints with the 816's addressing modes are also concerns on the eZ80. The only way to address

After spending time with the eZ80, I have to say most of your complaints with the 816's addressing modes are also concerns on the eZ80. The only way to address 24-bits of RAM is in ADL mode, which requires a specific mode switch, and then that screws up interrupts if you stay there. Further, code density is much worse in ADL mode, so staying there most of the time will actually make 24-bits of addressable RAM a problem. There's no provision for doing I/O block transfers in the ISA, so that makes data transfers on that half of the bus... questionable as to why that bus is even present.