Problems with VAX-11/780s, 4.1aBSD UNIX, and Able DH/DM Boards

[nomdenet at rand-unix]

   We are trying to bring up a VAX-11/780 under 4.1aBSD UNIX with three Able
single-board DH/DM lookalikes, but we're having problems:  On output, all
three boards drop (single?) characters once in a while.  Using a full-screen
editor on Ann-Arbor Ambassador terminals set up to display 48 lines, charac-
ters are dropped about three times when redrawing the full screen.  Redrawing
several times in a row shows that the characters are dropped at roughly the
same places in the order stream.
   Has anybody else run into this problem?  If so, have you solved it, and
could you tell us your secret?  We're running practically plain-vanilla 4.1a
straight off the distribution tape; are there fixes to the TTY drivers or
to the DH/DM drivers that might pertain?  Are the current run of Able DH/DM
boards functioning perfectly well in UNIX systems?

   Three or four months ago we brought up an 11/750, again under 4.1a, again
with an Able single-board DH/DM lookalike -- and this one has worked perfectly
from the time we first installed it.  We can take this old board and one of
the new ones, put them side by side in the 780's Unibus box, and the old one
works while the new one doesn't.
   We're talking with Able; they're quite cooperative, but it's slow going.
They've found us a back-level board that's almost but not quite from the same
production run as our working one.  This latter one is better than the newest
one, dropping characters only once when redrawing the full screen, but close
counts only in horseshoes.  Able says that our 4-month old working board and
the back-level board should be identical, but I found rework on our working
board that's not on the "almost" board.  Able is checking into the effects
of this difference, and that's where things stand today.

   We would greatly appreciate any and all help.


   Details:
		    Working board      Back-level board       Newest boards

Serial numbers          2761                 2448            3736, 3758, 3943
Revision levels
  PC layout              H5                   H6                    K6
  etch              10103002 rev A      10103002 rev A        10103002 rev B
  firmware               E4                   E4                    E4


   Early on Able said that our problem might be fixed by their latest version
of firmware, so they sent us an up-to-date loaner board, but it worked no
better than our original three boards.  (Loaner board serial number 755; PC-
layout revision H6; etch revision 10103002 rev A; firmware revision F5.)


   A. R. White
   The Rand Corporation
   (213) 393-0411, x7997 office
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