Re: Wrong timestamps in vax test results

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

> 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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