MSV11-Q info and interesting observation
spacewar at gmail.com
Mon Mar 16 15:40:43 CDT 2020
On Sat, Mar 14, 2020 at 2:12 PM Noel Chiappa via cctalk <
cctalk at classiccmp.org> wrote:
> the MSV11-Q
> sends a 'write' signal to _all_ the banks, and selects the one to
> use by use of the RAS signal.
> Has anyone else seen this trick used anywhere else?
Yes, that's very common.
If you have multiple banks, you have to do some form of address decode for
/RAS [*]. If you're doing that, there's no point to having another decode
system for /WR.
* Alternately, /RAS could be common and /CAS decoded. That effectively does
a refresh cycle on all non-selected banks, but using whatever the row
address just happens to be, so unless you add a LOT of additional
complexity, it's not very helpful, and increases power dissipation. I've
only seen a few designs that did this, and there didn't seem to be any good
reason for it.
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