[Info-vax] Uptime for OpenVMS

[Ken Fairfield]

On May 11, 9:56 am, JF Mezei <jfmezei.spam... at vaxination.ca> wrote:
> OK, in light of Bill Gunshannon's 4000 day uptime, I wanted to "edit"
> the output of SHOW SYSTEM....
>
> VMS Alpha 8.3:
>
> $START = "17=NOV-1858 01:00:00"
> $END = F$TIME()
> $write sys$output f$delta_time(start,end)
>
> %SYSTEM-F-IVTIME, invalid time
>
> If I change "start" to have a date last year, it works.
>
> Note that by having it at 01:00:00, it means that "start" isn't set to
> "0" and should not be considered a deltatime.
>
> Is this due to a 32 bit limitation in DCL that would not allow a
> delta-time greater than 32 bits ?

I think the problem is that a "proper" delta-time must
be less than or equal 9999-23:59:59.99 .  This is a general
statement.  See Help Date_Time Delta .

A delta time of 9999 days takes us back to about 27 years
to 24-DEC-1983, a far cry from 17-NOV-1858.

I used to have some understanding of the internal quadword
format of time (something simple like the number of centi-
seconds since 17-NOV-1858), and that a delta time is
identified as being a negative value.

I suspect that the limitation is not on the internal representation
of delta times, but that the output routines, e.g., $ASCTIM,
simply limit the value to fit in a 4-digit day field.

    -Ken