8 Mar
2016
8 Mar
'16
8:48 p.m.
On Mar 8, 2016, at 3:44 PM, Mike Ross <tmfdmike at
gmail.com> wrote:
But you will do something to allow memory to be switched in and out? I
presume this thing wouldn't work in an 11/20 unless it was strapped
back to 32KW? Or will the 11/20 be happy and simply ignore the
unaddressable memory beyond 32KW?
The Unibus has 18 address lines. This should work so long as the memory doens't
respond to I/O page addresses (the top 4kW of the address space). That's a
requirement for any Unibus memory on any PDP11. The difference between 11/20 and 11/05
vs. the others is that the lack of MMU means that the CPU can't generate addresses in
the range 28 to 124 kW. (I/O devices can, though, which would be rather interesting.)
paul
...
No, it will only have 128KW. Since it?s a single FRAM part, I?m not going to
try and ?stock? different flavors (especially since I?ll be having the boards
assembled at the board house).