VAX upgrades

[LARRY at JPL-VLSI.ARPA]

From:  Larry Carroll <LARRY at JPL-VLSI.ARPA>

Comparing 68000s and VAXen is risky business.  On some computational
benchmarks 68000s run .3 to .6 of a VAX, on I/O-intensive jobs 68000s are
usually left far behind.  And is the 68000 like the Lisa-2 with the CPU
having a part of almost every task, or does it farm out its load among
special-purpose co-processors?

Any upgrade has to take into account just what the upgrade is for.  If
your system has a lot of matrix math to do a VAX with an array processor 
may be what you need.  If you have a lot of screen-oriented text editors 
or bit-mapped graphics it's a lot more cost-effective to have a bunch of 
Lisa-2s hooked to your VAX so it isn't in danger of switching contexts 
for a single byte or bit.

The general principle is to use as much parallel processing as you can. 
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