> On Jan 31, 2017, at 3:07 PM, Mark Pizzolato <[email protected]> wrote:
>
> ...
> Simh tracks and adjusts for wall clock behaviors quite reliably. The problem
> here
> is that the OS is programming the interval timer device to generate ticks at
> 60Hz
> and we don't have other common examples that do this on the VAX. It seems
> like it is programming the interval timer register to -16667, and ticks per
> second
> is being computed to be 100000/16667 which ends up to be 59 rather than
> 60. This causes the very consistent calibration at 59Hz and therefore the
> timing
> results he is seeing.
But 1000000/16667 is not 59, it is 59.9988. Does SIMH actually deliver 59.0000
Hz for that setting? That would certainly cause trouble.
paul
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