...
> The RTC chip only has a resolution of 1 second. Certain calls in UNIX present
> time with finer resolution. To emulate that you put a counter on the
> video interrupt which fires every 60th of a second and you have 60th of
> a second resolution.

	OK. So, you write a process like xntp which, when system load allows,
slowly aligns your high resolution clock with the low-resolution RTC chip.


> If you're servicing a long SCSI interrupt and a video interrupt comes in,
> you've essentially lost it.

	Does anyone know it is possible to detect that a video interrupt
has been missed? If so, it might be possible to automatically correct the
time by adding a number of ticks to the counter.


> Basic problem: we need semaphores to protect
> critical code rather than shutting off interrupts for hours at a time.

	Yes, that is the optimal solution.

-- 
| Nigel Pearson, nigel@ind.tansu.com.au |"so we came up with a golden rule   |
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