The Case of the Missing Interrupts

[Keith Ericson]

In article <1990Feb16.170751.4059 at esegue.segue.boston.ma.us> johnl at esegue.segue.boston.ma.us (John R. Levine) writes:
>I have been having minor but persistent problems with my PC Unix system
>that appear to be related to missing interrupts, and I'm not sure how to
>go about properly diagnosing or fixing it.

NOTE: The following may well NOT be the cause of the problem.  I'm
only suggesting it to give you "something else" to try...

Some of the AMD (I thing it was) second-source versions of the Intel
interrupt controller (the 8259? I can't remember) ended up with a
too-high valued internal pull-up resistor when the chip went through
die-shrink.  But the symptom in that case seemed to be too many
(i.e., extraneous) interrupts and the machine would appear to be
running very slowly, especially if it were runnin UNIX.  The cure was
to tie some appx. 1k-ohm resistors from the interrupt-controller's 
IRQ-out pins to +5v.

My guess that the bad parts would've been weeded out by the time
Intel was building 302 motherboards: we had the problem with some
301's.

kEITHe