Setting Time Using the Battery-Backed Watch
(BBW) (Alpha and I64 Only)
The OpenVMS Alpha and I64 architectures maintain the current
date and time in the Battery-Backed Watch (BBW) across power failures
and system downtime. The BBW is functionally equivalent to the Time
of Day Register (TODR) that the VAX architecture uses. One difference,
however, is the BBW's constraint on the date range.
The BBW provides sufficient storage capability for only a
century. The OpenVMS Alpha and I64 systems date range has been redefined
as 1957 to 2056 to maintain correct leap-year processing and to
provide for the millennial transition.
In addition, the OpenVMS Alpha and I64 timing mechanisms have
been changed to allow 2-digit year support in the $ASCTIM system
service and the DCL command SET TIME. (Prior to this change, only
4-digit year fields were allowed.) With 2-digit support, you need
to enter only the last 2 digits of a year. The century associated
with the year field is derived from the placement of the 2 digits
in the 1957-2056 date range. For example: