11/45 hack?

[Eric Smith]

On Sun, Feb 8, 2015 at 9:40 PM, Paul Anderson <useddec at gmail.com> wrote:
> What I was trying to say is that it's not part of the 128 kw or 256 kb
> limit of the 45 and is fast.

The 11/45 (or 11/50, 11/55) Fastbus memory, whether MOS or bipolar, is
not directly on either Unibus, but it *IS* in the normal address space
of the machine, taking up an address range that is not then usable for
Unibus memory.  As far as the software can tell, it is just a memory
region that happens to be faster than typical Unibus memory.

The 11/45 (etc.) hardware doesn't perform any magic that makes it
behave in any way differently than normal PDP-11 memory, aside from
the faster speed.