You need to set the clock, using ntp, or a command, or whatever.
VAXen in general do not have an external clock that tells absolute
time. There is a clock that runs when power is off, but it only
keeps track of time for about a year before it wraps (it's a simple
counter).
Don't both of those depend on the particular VAX in question? The one
I know best (the KA630) does have a clock chip that keeps absolute
time (but with one-second resolution), and I'm fairly sure it doesn't
have any "simple counter" clock that runs when power is off - are you
talking about the TODR? It can be subsetted out and even if present
may not have battery backup; even if it does, the battery backup often
won't last anything like a year (the "year" probably comes from the
TODR wraparound time, which is between 497 and 498 days).
EL-00032-00-decStd32_Jan90 says
The counter has an optional battery back-up power supply
sufficient
for at least 100 hours of operation, [...]
[...]. If the battery has
failed, so
that time is not accurate, then the register is cleared upon
power-up.
and also says the MicroVAX-II TODR "Reads as zero, ignores writes".
EK-KA630-UG-001 (pages 4-3 and 4-4) agrees, describing the TODR as
"read as 0, no operation (NOP) on write".
Not that I expect SIMH's KA630 to be popular as a test machine; if
nothing else, if the simulation is accurate it's limited to 16M of RAM.
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