Making a accurate oscillator requires two key things
1. An accurate crystal (note stability is not the same as accuracy)
2. An oscillator circuit design that does not "pull" or otherwise change the
basic frequency of the crystal.

Clearly if you design a watch these are primary concerns, so even a cheap
watch is done well

For a computer this not a primary concern and I am sure there is a wide
range of accuracy in different models of computers depending on the amount
of attention paid to these issues. My current computer with an intel mother
board does keep could time.

Dan

--
Dan Hollands
1120 S Creek Dr
Webster NY 14580
585-872-2606

www.QuickScoreRace.com
wrote in message
ups.com...
Why do the battery powered clocks in personal computers tend to keep
worse time than quartz watches, even the $1 ones?

The computer batteries measure fine, at least 3.15V.

I thought that the problem was temperature swings in the computers
(25-38C), but a couple of cheapo watches taped inside the computers
kept better time.