8 Mar
2020
8 Mar
'20
10:37 p.m.
On 2020-03-08 22:28, Thomas DeBellis wrote:
The recent post about multi-threaded NNTP for VMS
(whaaay cool) jogged
my memory about something I had been wondering about.? This morning, a
large number of clocks got switched ahead an hour in the United States.
Tops-20 did it 'relatively flawlessly' as it has done so since the early
1980's.? Back then, a lot of systems didn't.? None of our IBM systems did.
Hehe... Always a problem...
A lot of that has changed nowadays with NTP clients;
even if the base
operating system doesn't support time change, an NTP client can address
that.? So all my systems advanced appropriately, as did an old radio
clock.? I'm not sure how *nix does it, but I don't remember Ultrix
having the code on our 8650 (or 8700). Tops-20 will do the change
whether or not a client exists as the code is in the monitor.
NTP does actually not solve this at all. NTP does all time in UTC. It's
up to the local machine to figure out if DST is applicable or not, and
how to apply it.
At the time (1980's), I don't believe that VMS
had internal code to do
the time change and NTP did not exist as such (some network time
services existed, but I don't remember whether there was a generally
available VMS TCP/IP package; we didn't have it).? I would assume that
this is handled now.? I hesitate to ask about RSX and RSTS, but I would
assume that the C compiler for RSX (with Johnny's TCP/IP interface)
could support an NTP port.? Anyway, the question is: how does VMS handle
the time change?
As far as I know, VMS still use local time. The TCP/IP package have some
handling of time zones and automatic DST. Exactly how it does it,
though, I don't know. I suspect it might change the system time.
In RSX, it's all local time, for sure. I do have an NTP client already.
I use a couple of logical names to tell what the offset from UTC is, and
NTP makes use of that. And then I have a batch job which runs twice a
year, at the time of the change between DST a not. And that batch job
then changes the logical name values, as well as change the clock.
My NTP client, by the way, is in fact written in C. But it is my own
implementation, and not something picked up from somewhere else.
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt at softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol