17 Feb
2015
17 Feb
'15
12:58 p.m.
On 2015-02-17 21:35, Noel Chiappa wrote:
So the description of the SSR3 register in
"Microcomputers and Memories"
(1982), on pg. 284, apparently has an error. It describes bit 5 as "enables
I/O mapping", but.... the QBUS 11's don't have any kind of I/O mapping that
I
know of. Or am I confused?
If it's the same as MMR3 in "older" CPUs, then yes, bit 5 is for Unibus
map relocation.
That said, though, there were CPUs that were used in both Qbus and
Unibus systems, so that bit could still be relevant to the CPU you're
reading about, depending on in which environment it was used.
Johnny