HELP! FPA hangs up VAX11/785 SBI-bus

[Dennis Olsson]

[what about a net.micro.vax group]

I have promised our (poor and lonely :-)) local DEC technician
to ask the netland for help:

        All you with a VAX-11/785 and its optional FPA
(Floating Point Accelerator), what kind of problems did you
have, when installing it, and how did you solve them?

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For my own account, I should add, that we have a VAX-11/785
(4.2 BSD) with
        1 TU-78, 1 UBA, 1 UDA50 with 1 RA81, and 4 DMF32
and our local DEC technician have - since Dec. 10 '84 - tried
to install a FPA.

The first FPA we had worked for 5 days, then it hang the SBI-bus.
DEC swapped all the FPA modules which cured the problem for 12
hours.  To resume:

        The FPA seems to have got the idea, that it will only work
        for 1-5 days, before it hangs the SBI-bus.
        Removing the FPA modules, make the '785 running again.

And it is *not* 4.2's fault, because DEC's own diagnostics are
quite cable of hanging the SBI them selfs!!

DEC haven't been able to fix the problems, but if they remove the
power, unplug the FPA's clock module (M7543) and plug it in
again, turn on power, then the FPA will work for a (very short)
while again.

Please reply by mail; if interest is high enough I'll summarise to
the net. Any help or suggestions will be most appreciated.
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Snail: Dennis Olsson, DIKU, Sigurdsgade 41, DK-2200 Copenhagen N, Denmark.
 UUCP: ..mcvax!diku!doss                           +45 1 83 62 57 ext. 13.