[cctalk] Address wrapping in PDP-11 MMU

I'm working on some code where it would be handy to map the top of the I/O page along with the bottom of physical memory. An obvious hack is to point the APR to the I/O page address needed, then set the length so that the address modulo 2^22 also covers the low memory range. It seems from the architecture manual that this would work, and SIMH seems to do this (since it adds VA and PAR then masks with a 22 bit mask). Would this work on real hardware? paul