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nistime-32bit.exe version 3.40
This version corrects a problem with writing time differences
and error messages to the log file (named nistime.dif by default).
The previous versions did not completely close the file after
each write, so that the system resources for opening files
were exhausted after the program had been running for some time.
This generally happened after about 50 writes to the log file.
The program continued to run once this happened, but it could no
longer write to the log file.
nistime-32bit.exe version 3.31
This version adds an error message if a user who does not have
administrator privileges tries to use the program to adjust the
system time. The request will be ignored by the Windows system.
The previous version of the program did not provide an error
message in this case. (The restriction that only a user with
administrator privileges can adjust the system clock generally
does not apply to versions of Windows before Win 2000.) A user
without administrator privileges can use the program to compare
the time of the system with the NIST server. The error message
will appear only if the user tries to use the data to adjust
the local clock.
nistime-32bit.exe version 3.15
This version adds a new parameter to the command line that can be used
to delay the start of the program. If the switch -s<number> is present
on the command line, the program will start as soon as the command is
processed, but it will not actually do anything for the number of seconds
specified by "number." Thus the switch -s60 will cause the program to start
but not to do anything for one minute.
This can be used to give a network connection time to be established, for
example. This switch may be required if the program is placed in the Windows
startup folder. If it is not used in this case, the program may try and query
a time server before the network connection is established.
There will be no display or other sign of activity during this initial
sleep period. The actual sleep time may differ from the specified value by
up to 1 second.
nistime-32bit.exe version 3.14
This version ignores the Winsock returned (non-zero) status code
WSABASEERR. Some versions of Winsock may return this status code even
when the operation succeeded. The previous version treated any
non-zero code as an error, which is the standard Winsock convention.
nistime-32bit.exe version 3.13
This version corrects a problem with the network delay calculation
when the program queries a server using NTP format. The previous
version sometimes computed the delay incorrectly when the actual
delay was less than 10 milliseconds. This error in the calculation
of the network delay also resulted in an incorrect value for the
computed time difference between the client and the server. This
error did not always occur, and the probability of it happening
increased as the actual network delay became shorter.
nistime-32bit.exe version 3.12
This version includes fixes for two problems:
1. If the program was stored in a directory whose path had an
embedded space (such as c:\Program Files\ ...), the previous version
did not handle this situation correctly in all circumstances. This
problem could affect both the configuration file and the file used
to store time differences and error messages.
2. When a system shutdown request is received, the exit status of
the program has been changed to prevent the program from interfering
with the shutdown process. The previous version could prevent the
system from shutting down in certain circumstances. This interference
was most commonly observed when the program was operating in "quiet
mode," but it could also affect a shutdown when the program was
running in the foreground with the screen display enabled.
nistime-32bit.exe version 3.11
This version includes fixes for two problems:
1. Changing back and forth between the daytime and NTP formats
on the same server without saving the changed configuration and
restarting the program. The previous version did not handle this
correctly.
2. Using a long path name to store the program itself or one
of its configuration files. The previous version did not check
for a name that was longer than the assigned array.
nistime-32bit.exe version 3.1
In addition to several new help messages and small improvements to the
internal code, this version has two significant changes from the previous
version:
1. This version allows you to store the configuration file and
the file containing the list of NIST servers either in the Windows
system directory (usually c:\windows or c:\winnt) or in the same
directory as you use to store the program itself. (The previous
versions always stored these files in the Windows system directory.)
The directory where the program itself is stored is used by default.
You can change this behavior using an option on the File menu of
the program. The program will search both of these locations each
time it starts, and will use the files in its home directory if
they exist both there and in the Windows system directory. Thus
this new version is completely compatible with the previous version,
and no change is necessary to read files generated by a previous
version. However, this version will write new configuration files
to its home directory by default.
2. This version supports operation in the background, which is
called "quiet" mode. The program runs completely in the background
in this mode -- it does not have any display and will not accept input
from the keyboard or the mouse. Once it is started in this way it will
continue to run in the background until the system is halted or the
program itself is stopped using the task manager. This option may be
selected in two ways: either by adding the parameter "quiet" to the
command line or by checking a box on the periodic queries menu. Look
at the Help | Quiet mode entry for more information about this choice.
(Note that this mode is very similar to a Windows NT "service.") When
using this option, keep in mind that the program requires a connection
to the Internet to query our servers, and that it may not work very well
if you connect to the Internet using a dial-up telephone call to an
Internet Service Provider.
The 16-bit version of the program has not been changed.
nistime-32bit.exe version 3.0
The file nistime-32bit.exe is new version 3.0. In addition to several
new help messages and small improvements to the internal code, this version
has two significant changes from the previous version:
1. After you query a server, the same server will be automatically
re-selected after a few seconds. In the previous versions of the program
you had to manually re-select the server after each query.
2. This version supports queries using the Network Time Protocol (NTP)
using udp/ip port 123 in addition to requests in the daytime protocol
which uses tcp/ip port 13. The daytime protocol was the only format
supported in previous versions. The choice between the protocols is
implemented by adding check boxes to the File | Select Server menu.
The communication format can be different for each server. Your
choices are stored in the configuration file, and will be "remembered"
when you re-start the program if you save the configuration file.
The choice between the two formats depends to some extent on your
network connection. The NTP format measures the round-trip network delay
on each cycle and is therefore potentially more accurate. However, this
potential is often not realized because of jitter in the network delay
and because of the poor quality of most computer clocks.
------------------------------
nistime-32bit.exe version 2.6
The file nistime-32bit.exe is new version 2.6. This version fixes
a problem with daylight saving time. The problem is only seen by a
user who is in a zone that normally has daylight saving time, but disables
the automatic correction for it. The intention is to run on standard time
all year, but the Windows registry does not accurately reflect this in
all situations. This is not a problem with Win NT or for users who use
the default setting for daylight saving time in their local time zone.
----------------------------
Changes in version 2.5. In addition to a number of
minor changes, this version contains two major improvements:
1. Handling of the conversion from UTC to local time in non-US time zones.
The improvement will be especially noticed by users in the Southern Hemisphere,
especially those in New Zealand. The difference between local time and UTC is
now read directly from the registry entry. The transition dates to and from
daylight saving time can also be displayed using the daylight saving time menu
option. Changes to the registry time zone setting (made using the control
panel Date/Time function, for example), should now be detected without
requiring a re-boot of the system, although it may still be necessary to stop
and re-start the program itself.
The direct connection between the program and the registry settings means
that you cannot easily use the program if the registry setting for your location
does not correctly indicate the offset between your local time and UTC or if the
transition dates to and from daylight saving time stored there are wrong. A
program called "tzedit" (usually part of the Windows distribution) can be used
to fix these problems, or you can edit the registry directly. Be warned that
direct editing of the registry can get you into real trouble and is not for the
faint of heart.
2. If periodic queries are enabled, the program will dynamically estimate
the frequency offset of the local clock and will make small adjustments between
calibration cycles to correct for this frequency offset. This should improve the
accuracy of the local clock when using the same interval between calibrations or
should make it possible to realize the same level of accuracy with less frequent
calibrations. (This capability is not supported by all versions of Windows. It
will work on Windows NT, but generally does not work under Windows 9x.)
The frequency of the clock oscillator in most computers is quite sensitive
to temperature, and any algorithm that attempts to correct for variations in
this frequency will be limited by the effects of changes in the ambient
temperature on the frequency of the oscillator. The capability to make small
adjustments between calibration cycles therefore may not work as well as you
would think.
If you choose periodic queries, there is generally an optimum interval between
queries which you will have to determine experimentally. Choosing an interval
that is too small will not do any harm, but will use computer resources and
network bandwidth without improving the accuracy of your clock because the
internal frequency estimator would have done just as well on its own. Choosing an
interval that is too large will degrade the accuracy of your clock because the
fluctuations in the ambient temperature will defeat the frequency estimator.
If you are interested in exploring this question, you should enable the option
to write the time differences to a file, and you should examine this data
as you vary the interval between calibrations.
These changes are not incorporated into the 16-bit version of the program,
which is intended for Win 3.x and 95.
That version supports direct setting of the time zone, so that improvement 1
is not needed. In addition, Windows 3.x and 9x do not support slewing the clock
frequency so that improvement 2 would not work in those environments anyway.
Please direct questions or comments to:
time@time.nist.gov
4 October 2002