On Wed, 25 Feb 2004, Chris Tribo wrote:

> 	I believe that the psu fan has some kind of temperature or
> rotation sensor system. If the fan is not spinning fast enough it will
> kick off. I think there's also a thermal sensor in the CPU itself, but
> NetBSD doesn't monitor it I don't believe. I'm probably spouting
> conjecture more than actual fact, but hopefully that gets you on your way.

 There's a software-readable thermal sensor in the PSU of all DECstation
5000 machines.  It's available as a bit in the CSR in the /200 and in the
SIR of the I/O ASIC in the others (therefore the latters can use it as an
IRQ source).  The bit is active if an overheating condition happens -- I
don't know what temperature it corresponds to (and I'm not that interested
in checking it empirically).

 I haven't heard of any temperature sensor in any of the processors used
for the DECstation.  There may be one outsidew the CPU on the KN04 and
KN05 daughtercards as there's a bunch of new registers of littly known
purpose in the combined MB/MT ASIC there.

  Maciej

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +