Shawn Gordon wrote:
>
> I have gotten a lot of information on the clocks so far, but I am still not
> sure of the answer to question.
> ....
> I have gotten conflicting information on how to set the hardware clock, so I
> am curious, given my above situation, can anyone tell me the proper way to
> set the clock and timezone?
>
Ok, let's see if I can make the pool a bit muddier.... :)
You are on the west coast, USA. The natural (non-daylight savings) time
difference between you and GMT is -8 hours. During summer, the
difference will
be -7 hours.
MPE will not be able to work this out by itself, you will need to
correct MPE time every 6 months.
CTIME, however, uses the TZ variable, and will be able to correct
itself. CTIME uses the GMT clock as it's base, and looks up a table
(TZTAB.LIB.SYS) which tells it what time to return based on what you
have set the TZ variable to. So, using PST8PDT, CTIME will return an
offset of -8 during winter months and -7 during summer.
At the moment, it looks like your GMT is out by an hour. Your MPE time
is correct, but that's just because the offset is just set to -8 hours
instead of -7. CTIME is assuming GMT is correct and as it is summer, is
returning -7. Let's go through the steps to fix GMT and MPE time. Note
that a reboot is NOT required.
We need to refer to the SHOWCLKS utility in TELESUP, as the SHOWCLOCK
command does not tell us anything about CTIME....
:showclks.pubxl.telesup
SHOWCLKS/XL A.10.00
DEBUG/iX C.05.07
HPDEBUG Intrinsic at: 584.00007258 PROGRAM+$198
PRIV=$3 := $0
*************************************************************
*** ***
*** Greenwich Mean Time : WED, AUG 28, 1996, 5:20 PM *** <===
wrong!
*** GMT/MPE offset : -8:00:00 *** <===
wrong!
*** MPE System Time : WED, AUG 28, 1996, 9:20 AM ***
*** ***
*************************************************************
**** C Library Information ****
Current value of Time Zone(TZ) variable : PST8PDT
CTIME function return : Wed Aug 28 10:20:06 1996
:setclock timezone=w7:00 <==== We set the correct offset
between
<==== MPE and GMT.
SYSTEM TIME: WED, AUG 28, 1996, 9:20:39 AM
CURRENT TIME CORRECTION: 3600 SECONDS
TIME ZONE: 7 HOURS 0 MINUTES WESTERN HEMISPHERE
*** Note that we have now got the correct offset, but have started a
correction, which if allowed to continue will result in MPE time being
out by an hour. So we now need to tell MPE what the correct time is,
this will also set the GMT clock to the correct time (as it works that
out from the timezone specified in the above command). Not that if the
correction was a negative value, we would have to do a SETCLOCK ;CANCEL
before continuing.....
:setclock date=08/28/96;time=9:20;now
:showclks.pubxl.telesup
HPDEBUG Intrinsic at: 584.00007258 PROGRAM+$198
PRIV=$3 := $0
*************************************************************
*** ***
*** Greenwich Mean Time : THU, AUG 28, 1996, 4:20 PM ***
*** GMT/MPE offset : -7:00:00 ***
*** MPE System Time : THU, AUG 28, 1996, 9:20 AM ***
*** ***
*************************************************************
**** C Library Information ****
Current value of Time Zone(TZ) variable : PST8PDT
CTIME function return : Thu Aug 28 09:20:36 1997
As can be seen, GMT, MPE and CTIME values are all correct. Note that 2
SETCLOCK commands were necessary. Note also, that I have used the ;NOW
in the above command. Be very wary using this if you are changing MPE
time to an earlier time, as this can affect application logging.
In October, when daylight savings finishes, CTIME should look after
itself, GMT will be the same, so all we need to do is to fix MPE time.
This requires only one SETCLOCK command. Now that you have the correct
GMT, this should be all you ever need to do from now on (once every 6
months).
:SETCLOCK TIMEZONE=W8:00 (and W7:00 in March).
Note that this will set in place a gradual correction, wait an hour or
two for the correction to complete (the SHOWCLOCK command will tell you
if a correction is taking place).
I hope this has made things a little clearer.
Damian (who now needs to set his system back to good ol' Aussie time).
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