Absolute/direct access of Ri occurs most often within the selected bank, as a consequence of missing mov Ri,Rj instruction.
Nevertheless, the given problem can be solved in two ways:
- mov Ri,ARj is a 16-to-16 bit transfer (as long as i,j={0,1}) so the upper byte is moved implicitly
- all upper bytes can have dedicated SFR positions plus the "shared" RiH; call them say ARiHb for high Ri bank b.

The idea of having R2,3 as high bytes for R0,1 occured to me, too, as these couples are often used as pseudo-16-bit registers and moved to and from dptr. I rejected this idea because:
- this means a bigger deal of incompatibility
- reduces the number of general-purpose registers (accessed in fast instructions) to 4 per bank.

Jan Waclawek

PS. C stands for Complicated, I suspect, but what doeas the 2nd I mean?