<I think it's safe to guess that the clock is battery backed, probably
<Ni-Cads.  Perhaps with your VS2000 it's old enough that the batteries are
<unable to charge anymore. Though I'm still not sure what was going on with
<my early 20th century VAX experience.

most of the vaxen used nicads to backup the click and even good one would 
only hold up the clock for a few days to a week.  It's not the clock chip
that flattens them, their internal leakage self discharges them.

If they have been allowed to sit discharged you may have to replace them or
pull them and hard charge them or the internal charge circuit will not 
charge them.  Hence the date gets lost on power down.

The same pack is unsed on the PRO, MicrovaxII, VS2000 (and maybe others)
and it's three AAA sized nicads.  The 3100s use a PC style 60ma 3cell 
pc-mount nicad pack.  A three cell pack used for corkess phones would work
well enough if the batteries are failed(leaking or won't charge).

Allison