RT-11 DY install - test-drb@ccmp.vtda.org

18 Oct 2018

...
  From: Bill Gunshannon 
...
 > From: Jerry Weiss  
...
 > Note: Apparently the RY emulation won't load
if more than 256K memory 
> is specified ... I'm entirely not sure why SIMH has to enforce this
> as its possible to work around .. Anyone know how to override and load
> in SIMH? 
...
  If it didn't it wouldn't be emulating real
PDP-11 hardware. ...
 RX02 systems and they do not work with more than 256K. 
Right, the hardware only has 18 bits of 'buffer address' (in both UNIBUS and
QBUS versions). But one can still plug one into a QBUS system with more than
256KB, and use it - you just can't use memory above 256KB for transfers
to/from the RX02, since it cannot physically create those addresses.

If sounds from Jerry's description as if SIMH refuses to emulate an RX02 if
the emulated system is configured with more than 256KB - which would be a
bug, if so.

	Noel