XY753 problem solved

[Dan Davison]

A while back I posted a note about a Xylogics 753 controller which we
couldn't get to work in two Sun-3/280s, with three different types of disk
and two different sets of controller cables.

The problem was the Dawn VME adapters, or the voltage Sun puts out on the
backplane.  When plugged directly into the backplane, the controller
worked fine (actually, both did).  We traded the Dawn adapters for Ilimite
(sp?) adapters and those work fine.  (I don't have the name of the person
who suggested plugging the controller directly into the backplane...but
thanks!).  Software Associates, now Cita Technologies, exchanged the
adapters without any fuss.

Moral of the story: Sun may not put enough <voltage,current> on the bus to
work with 3:2 adapters that bring a 2-high board out to the back of the
machine.

Of course, this also means you have to cobble up some way of attaching
cables to the 753 when it is buried in deep inside the 3/380 that won't
short out or damage neighboring boards.  So it goes.

dan davison/theoretical biology and biophysics/t-10 ms k710/los alamos
national laboratory/los alamos, nm 87545 USA/dd at lanl.gov/505-665-1355