[time-nuts] Accurate timestamping on computers (previously: For mywhole life timezones have been weird)

[Sarah White]

On 11/3/2012 8:26 AM, WB6BNQ wrote:
> Sarah,
> 
> I am having a hard time understanding your problem.  Or at least what you see as
> a problem.  I am not sure what you are really complaining about here ?  Is it the
> daylight change ?  Or is it a dual boot problem which would suggest you do not
> have some settings in their rightful place ?
> 
> The computer is merely displaying a form of time representation on the screen
> (human device).  Internally, it seems to me, the computer's operating system is
> merely keeping a count of the passing seconds since reading the actual hardware,
> hardwired clock chip upon boot-up.  After the initial boot it no longer reads the
> hardware clock chip to my understanding.  If that is the case, it would suggest
> that a flag is recorded as to the daylight savings time change either in firmware
> or perhaps on the mass storage device that has the operating system.
> 
> It is possible that the hardwired clock chip may keep track of the daylight
> savings function.  If that is the case, perhaps the way to deal with it is to
> write a a small program that will make sure that hardwired chip stays in the NON
> daylight mode as part of a boot-up routine.
> 
> As for the microsoft reference, it suggests not using a particular registry entry
> and if it is there to delete it.  On my computer it is not present in the
> registry.  While that only fixes some kind of system unresponsiveness issue, it
> does not seem to keep the daylight function from changing.
> 
> With all the clock Synching available via the internet, it seems to me your clock
> should not be an issue in of itself.  However, I am retired, as such, do not have
> a watch and pay little attention to the wall clock.
> 
> Bill....WB6BNQ

----begin reply 1----

@ Bill / WB6BNQ <wb6bnq at cox.net>

The hardware chip does not do any such "tracking of the daylight savings
time"

Here is a reference better explaining the problem:

http://www.cl.cam.ac.uk/~mgk25/mswish/ut-rtc.html

----begin reply 2----

On 11/3/2012 8:38 AM, lists at lazygranch.com wrote:> Microsoft also does
updates regarding the day daylight savings time changes, similar to that
Apple message.
>
> I suspect I'm not following this thread correctly. What I got from the
orignal thread is Microsoft will "thunk" the RTC during the switchover.
I'm going to make it a point to insure NTP is logging correctly, and
then look for a time error at the switch over. (2AM I think.)

@ <lists at lazygranch.com>

Correct. This is the primary concern. Tweaking the clock twice a year to
match up with local time is not desired.

Seeing as I'm in the process of installing a hardware refclock (trimble
thunderbolt connected via serial port) for my NTP, it is highly
problematic and potentially error-prone for microsoft's OS to touch the
bios hardware clock AT ALL.

I'm entertaining the notion of writing a kernel-mode hardware timestamp
/ PPSAPI driver to pull the signal off the 1 PPS port on the tbolt one
way or another.

I plan to do this on windows. This is something I want to attempt even
though the NT kernel doesn't have the best reputation for realtime
hardware / interrupt handling. Plan is to put in a non-zero amount of
work, up to and including steps where I go through the driver signing
run-around with microsoft to actually have it fully recognized by the OS
without modification. (unless budget issues are a limiting factor)

... Possibly, this project could even using a board which physically
goes on in a PCI express bus slot in order to do hardware timestamping.