[Simh] pdp11 i/o addressing

[Mike Stramba]

Greetings,

I'm trying to figure out how console I/O works with the PD11.

Or more generally I/O addressing

E.g.
A  "sh TTO"  gives :

TTO, address=17777564-17777567, vector=64, 7p

And 17777564 (octal) is 4,194,164 dec, which is obviously out of range
of the 64K addressable by any MOV instruction.

But various diagnostic routines, e.g. below, are using
     movb rX,@#177566       ; output to console

https://www.ak6dn.com/PDP-11/M9312/23-248F1/23-248F1.mac

Are I/O devices always at the "top 64k" of memory ?

If so, why doesn't  SH DEV display :

xxx xxx-177 777  ?

Mike