In article ,
Mxsmanic wrote:

Woody Brison writes:

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

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

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

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

That is true if all activity is confined to a single computer. When
multiple computers are involved, however, they must be synchronized.
And if the computers interact with other computers outside local
control (as by communication over the Internet), then they must not
only be synchronized, but they must be synchronized to a universal
standard, such as UTC.

This is why clock accuracy is important.

In the old days when every PC was completely isolated, time hardly
mattered at all, and often people would use PCs without bothering to
ever set the correct date or time. Nowadays, almost all PCs have to
be at least approximately synchronized to the correct time of day, and
often very precise synchronization is required.

In almost any instance where a high degree of precision and
synchronization is needed, the computer will be running a version of NTP
software which can provide precision time from even very poor CPU
timebases.

"Ordinary" computers don't need that degree of precision, and a
once-or-twice a day comparison to an NTP server somewhere on the 'net is
all that's required.

Isaac