At 3:41 PM -0500 3/5/03, der Mouse wrote:
>  > My understanding is that the problem affected most 68K Macs, and that
>>  it was caused by the clock interrupt having the lowest priority
>>  rather than (as would be usual) the highest.
>
>I have a IIci which suffers from _something_ of the sort.  When sitting
>idle it keeps moderately good time, but put it under any sort of load
>and it starts losing ticks like mad.

No "something" about it.  That's the problem.  Time interrupts are 
blocked during any disk or Ethernet access.  MacOS works around the 
problem by rereading the RTC after every floppy access, and elsewhere 
as well probably.

Pity the RTC only has, like, 1 second readout accuracy.  Otherwise 
we'd have made the RTC the system clock and solved the problem that 
way.
-- 
The opinions expressed in this message are mine,
not those of Caltech, JPL, NASA, or the US Government.
Henry.B.Hotz@jpl.nasa.gov, or hbhotz@oxy.edu