"Woody Brison" bravely wrote to "All" (15 Nov 05 09:51:18)
--- on the heady topic of " Why aren't computer clocks as accurate as cheap
quartz watches?"

WB From: "Woody Brison"
WB Xref: core-easynews sci.electronics.basics:146967
WB sci.electronics.repair:348689 alt.comp.hardware.pc-homebuilt:352599


WB After reading much of this thread, and a lot of it has been
WB quite insightful... I'd like to add 2 more cents.

WB w_tom wrote:
There are two ways to do as suggested. The first is to make
'Benjamins' part of the technical facts during design....
... the technical reason for high verses low accuracy
timers was provided. Computer motherboards don't have the
trimming capacitor and the oscillator is subject to wider
voltage variations. Why this technical decision was made was
not asked and would only be speculation.

WB So, two sides of the coin... then, there be the THIRD side of the
WB coin.
WB Why do you have a clock on your computer? Can't afford a watch
WB or a desk clock or a wall clock?

WB The answer is that a clock on the computer is useful to record
WB creation/change time on files.

WB It doesn't really matter if the file was modified at 6:00.00 000000
WB or 6:00.00 000035

WB What matters is if one file was created before another. You're
WB compiling, but the source hasn't changed, or has; the params file
WB has been changed since X,Y, or Z... that kind of thing.

WB On a computer, Approximate Time is almost always all that's really
WB needed; a clock that ***always runs forward***, and keeps time within
WB a few minutes a day.

WB Even if Perry Mason drags you into the witness stand and confronts
WB you with file dates and times, approximate is probably good enough
WB to acquit you or convict you. If in the rare case it's not, bring in
WB your
WB expert to explain that computer clocks are often not accurate.

WB Wood

Not only that but people sometimes purposely change the date and time
on their system. For example in order to run programs that can't work
past a certain date like 1999 or for some other reason. I still recall
the PC and XT would accept [Enter] to the date and time question so
that files would end up dated 1980... etc.

A*s*i*m*o*v

.... Old pinballers never die, they just flip out.