26 Feb
2006
26 Feb
'06
10:06 a.m.
On Fri, 2006-02-24 at 12:26 -0800, Don North wrote:
If Guy really can implement a 22b examine/deposit physical memory in a
pure SPC slot kudos to him. The only way I can think of possibly doing
it (thinking out loud again :-) ) is to steal a UNIBUS map entry and on
each exam/deposit set it up correctly to map the 18b unibus address to
the desired 22b address. I don't recall if the UNIBUS map is accessible
from the UNIBUS itself (if it is, this could work; if not, then it won't).
Ding! Ding!
Yes, I'm planning on co-opting one of the map entries while the system
is "halted". Since it will require multiple steps (saving/restoring the
contents of the map entry before and after the examine/deposit) I'll
have to implement some sort of sequencer and a bit of a scratchpad (and
also forcing the system into 22-bit addressing).
From what I've been able to tell, the UNIBUS map is
accessible from the
UNIBUS. I have to do a bit more research to make sure.
--
TTFN - Guy