9 Feb
2015
9 Feb
'15
4:38 a.m.
From: Paul Anderson
it's not part of the 128 kw or 256 kb limit of the
45
Err, don't think so - that limit is in the addressing hardware in the CPU
as well as in the UNIBUS.
From: Eric Smith
The 11/45 (or 11/50, 11/55) Fastbus memory, whether
MOS or bipolar, is
not directly on either Unibus
Actually, my understanding is that it is on UNIBUS B (or 2), via a second port
to the memory; see this post:
http://www.classiccmp.org/pipermail/cctalk/2015-February/003460.html
which gave my understanding of how it works. And of course if you connect the
two UNIBI together, it's therefore directly on UNIBUS A (or 1), as well. I.e.
DMA devices can do transfers to/from it.
Noel