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Why aren't computer clocks as accurate as cheap quartz watches?
In , on 10/28/05
at 09:38 AM, lid said:
The question of why the PC clock is so inaccurate, and yet more expensive
than a cheapo watch is simply a matter of "how ya gonna get the
information out of the cheap watch, and into the PC?" The clock itself,
and the crystal are only a portion of the hardware required by a PC to
know what time it is. The additional requirements increase the sicon die
size, as well as the complexity of the design, so the higher cost is to be
expected. If you can get the time out of a cheap watch, in binary form, at
the proper levels, and the proper timing specs, without raising the price
of the $1 watch, a lot of people would like to hear from you ;-)
Well you don't need to get any data only the timeing reference signal.
That can then drive an ordinary RTC chip.
I thought the question involved the clocks on the MB. Lacking an external
device, or manually entering the time, the PC has to be able to read and
set the RTC at some point, and that kind of interface costs more than any
cheap quartz watch. Once the OS knows the real time, it can try its best
to keep it accurate, but PCs are not real time operating systems, so that
can't happen. There must be an accesible RTC device, with a data
interface, and control lines.
Did I miss something in your point?
Mark
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