response time

[John J. Lee]

Peter Hansen <peter at engcorp.com> writes:
[...]
> Strange, but based on a relatively mundane thing: the frequency (14.31818MHz)
> of the NTSC color sub-carrier which was used when displaying computer output 
> on a TV.  This clock was divided by 3 to produce the 4.77MHz clock for the
[...]
> in time-keeping, which then counted on every edge using a 16-bit counter
> which wrapped around every 65536 counts, producing one interrupt every 
> 65536/(14.31818*1000000/12) or about 0.5492 ms, which is about 18.2 ticks
[...]

That doesn't explain it AFAICS -- why not use a different (smaller)
divisor?  An eight bit counter would give about 0.2 ms resolution.


John