[Simh] Simulating a GT40

[Lars Brinkhoff]

Mark Pizzolato wrote:
> this certainly could easily solved by setting the RAM in the system to
> 64K and merely loading the ROM data into the appropriate address
> range.

I tried this, but got:

  Address space exceeded

I have "set cpu 64k".  But sys_load checks address 166000, and
ADDR_IS_MEM is not happy.

I'm looking at how the SIMH PDP-11 cpu does an instruction fetch.  It
seems to go through ReadE, which will use iopageR if necessary.  I think
it should be possible to make a ROM device with an address range in the
IO page.