Date   : Fri, 18 Jan 1985 19:20:00-EST
From   : Herb Lin <LIN@Mit-Mc.ARPA>
Subject: macrotech board update...

I have bought a Macrotech MI-286 from Gifford Computer Systems, whose
problems I described in a previous note.  Their recommended cure was
to upgrade my hard disk controller board from a Morrow HDCA-4 to a
Compupro Disk2.  However, a conversation with the techs at Macrotech
resulted in confusing information: Macrotech tells me that the problem
is most likely in the Compupro RAM 16 boards that I am using; these
are alleged to have a wrong pull-up resistor in R1.  They said that
the fix would be to put the correct resistor there, and all would be
well.  They also said that other Compupro memory boards did not have
the same problem, and that they knew of people with Morrow controllers
running Macrotech boards without difficulty.

I tried something else, with their concurrence.  I replaced my 4 RAM
16 boards with a RAM 22 board, and tried running the Macrotech board
with that configuration.  Here I had a very strange experience -- the
system worked fine in the morning, but then I shut it down.  In the
afternoon, I powered up again, and found that the system no longer
worked.  Closer investigation revealed that my hard disk directory had
been trashed in a very subtle way, and Gifford says that their other
customers with Morrow controllers and Macrotech boards have reported
similar trashing problems.

I have decided to take Gifford's solution, since they were 
generous in offering me some trade-in value for my Morrow controller,
*and* assuring me of refund if their solution did not work.

More as it develops.

herb lin