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[jazzy at aerospace]

From:  Richard Fitzgerald <jazzy at aerospace>


   In reply to your message asking for suggestions, here are a few based
on what we have running on a 750 at my site.

   First of all, the best (and cheapest(?)) was to swap out the old
memory controller for a new 64k chip controller.  We now have a full
8 meg on a 750.  Makes one heck of a difference, also an FPA was 
added, since we do heavy INTEL processor development work on the machine
and it needs the FPA.

  Second was the removal of all interrupt driven devices from the unibus,
either totally, or replaced by a newer device (dz-11 -> dh/dm or vmz-32)
which does dma.  Anything and everything on the unibus of a 750 kills
any performance you might see if it is interrupt driven.  Especially if
you are in to heaving editing as you say.

  Third, and perhaps the best, was the total replacement of all disk drives
including the system disk (was an rk07 *ugh*) with Fujitsu Eagles.
The important thing here is to put the system Eagle and the user Eagle(s)
on their own MBA's!  This made a tremendoues improvement in overall 
performance, and in fact we can even use the 750 as a real computer now!

  These additions may seem costly, but you can play with prices and
mix and match the above to acheive a compromise.  The new memory
controller with 2 meg installed was only $10K, and since each additional
(trendata) memory board was only $2900, it was not too bad.  The Eagles
were purchased from S.I. for about $18K (which includes an MBA AND 9900
controller)  each for the first two (to give the 2 MBA's) and then add
on drives (we have 2 user drives and 1 system drive) are about $16K. 
Overall, UNIX will perform quite well under this, and rather than go into
details on this message (I hate long mail) perhaps we can talk more
about the Unix configuration side of this in a future letter.  However
I have seen most of our performance come from the new hardware and not
much unix twiddling.  By the way, we are running anywhere from 30-64(max)
users on this machine, running edits and such.  Response is not fantastic
when you get above 32, but much better than I have seen elsewhere.

-Rich Fitzgerald
(jazzy at aerospace)