From: utzoo!henry
Newsgroups: net.micro
Title: software refresh on Sun boards 
Article-I.D.: utzoo.2733
Posted: Wed Jan  5 17:52:08 1983
Received: Wed Jan  5 17:52:08 1983

One thing tucc!watts didn't mention about the software memory
refresh on the Sun.  It does not necessarily have to be 128 NOPs
that the software executes every 2 ms.  It's quite possible for
that code to do something useful, provided that it does touch
all 128 possible combinations of low-order bits.  This would
in general require hand-crafted assembly code, but the amount
is small enough to be manageable.  Tom Duff at Lucasfilm, for
example, does his mouse polling in the refresh routine.