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NISTIME for OS/2 Warp 3 and Warp 4 release notes
Version 0.2d 02-nov-2001
Pieter Bras
Cambridge, MA
pbras@pobox.com
Description
-----------
This program is an update of the NISTIME for OS/2 program produced
by Michael Thompson in 1993 (see README), which was ported from the
Unix code written by Judah Levine at NIST.
Functional differences in the current version:
- default time server choice changed from 132.163.135.130
- command-line parameter allows user to override the default server choice
- command-line option for maximum network delay (default = 250 msec)
- more precise time reporting and setting (+/- 0.5 second)
- modified built-in help to describe above features
Also:
- included official NISTIME icon (copied from NISTIME for Windows)
- REXX script to query multiple NIST servers for correct time
The time is set to within +/- 0.5 second. This is not a limitation of
the NIST protocol, which should allow for better than +/- 0.1 second
accuracy, but rather is the best that can be expected using the native
OS/2 API DosSetDateTime().
Usage
-----
This section complements the nistime.man file which should be read first.
You can run nistime.exe by itself but it is more useful to use the REXX
script nistime2.cmd in because that will try a list of servers until it gets
a satisfactory response. Any given server may be unavailable or "unhealthy"
or overloaded from time to time. Note that a NIST time server will give a
"connection refused" response if its load approaches 1500 requests/second.
The file my-nist-srv.lst has the time servers ordered by distance from
Boston, MA. You can rearrange the order of the servers to suit your own
geographical location but be sure to preserve the format of the file.
The lower the round-trip network delay, the less resulting error in the time
calculation. One way to determine which servers respond best to your location
is to run the command "nistime2 -m2 -d1" and observe the round-trip times
from the various servers. None of them will be able to respond within one
millisecond so the program will try all the listed servers. You may need
to redirect the output to a log file to be able to compare the times better.
Note that you will need to redirect both sdtout and stderr, as follows:
nistime2 -m2 -d1 my-nist-srv.lst >logfile 2>&1
The default round-trip delay limit of 250 milliseconds should be enough for
users within the USA. For instance I typically get round-trip times of 40-50
milliseconds from the nist1-ny.glassey.com (Boston-New York-Boston). If you
have a particularly slow link then you may need to override the default delay
using the -d option.
Note that NISTIME will work properly only with NIST time servers. Other
time servers that provide a "daytime" service (RFC 867) will use message
formats that are incompatible with NISTIME.
Nistime2.cmd can be invoked from within another script such as startup.cmd.
Further Information
-------------------
Some currently available NIST time servers are found listed in the
included file nist-srv.lst which is occasionally updated and can be
downloaded from any NIST ftp server. Also:
132.163.135.130 (old NISTIME default)
time_a.timefreq.bldrdoc.gov
time_b.timefreq.bldrdoc.gov
time_c.timefreq.bldrdoc.gov
An html list of NIST time servers can be found at:
http://www.boulder.nist.gov/timefreq/service/time-servers.html
Further information can be found at:
http://www.boulder.nist.gov/timefreq/service/its.htm
Compatibility
-------------
The current version is backward compatible with the original version of
NISTIME for OS/2 (from 1993). The time offset is now reported to the nearest
hundredth of a second (for example, -0.25).
This program has been tested on the following OS/2 configurations:
OS/2 Warp 3 Connect (FP 40) with TCP/IP stack 4.02y
OS/2 Warp 4 (FP 10) with TCP/IP 4.1 (updated with WR8620/UN_2001)
OS/2 Warp 4.5 (MCP) with TCP/IP 4.3 (updated with IC27649)
No guarantees are made about compatibility with any other OS/2
configurations. Program is provided "as is" and the author disavows
responsibility for compatibility problems or any other difficulties
that may arise from its use.
Developer details
-----------------
IBM C Set++ 2.01 for OS/2, updated with fixpacks CTM0010,CTC0012,CTU0003
IBM Developer's Toolkit for OS/2 Warp Version 3 (from DevCon 12)
IBM TCP/IP Version 3.0 for OS/2 Programmer's Toolkit (from DevCon 12)
OS/2 Link386 3.00.002
New Files:
nistime.c -- updated source
nistime.exe -- new executable
cl.cmd -- compile/link commands used to generate new executable
nistime.ico -- official NISTIME icon (copied from NISTIME for Windows)
nistime.man -- includes description of new/modified features
README.2 -- this file
nist-srv.lst -- official list of NIST time servers
my-nist-srv.lst -- above list distance-optimized for Boston, MA
nistime2.cmd -- REXX script to query a list of NIST time servers
Revision History
----------------
Ver 0.2d (02-nov-2001):
- improved error checking and better error messages
- changed default NIST time server again
Ver 0.2c (09-jun-2001):
- use msADV value in NIST message to reduce clock error
- measure round-trip network delay to reduce clock error
- measured clock offset reported to nearest .01 sec
- return codes changed to uniquely identify various error conditions
- command-line parameter for maximum network delay (default = 250 msec)
- output time server host ID only if -m2 option is selected
Ver 0.2b (14-may-2001):
- suppress output of time server host ID if -m0 option is selected
Ver 0.2 (13-may-2001):
- default time server choice changed from 132.163.135.130 to time.nist.gov
- command-line parameter allows user to override the default server choice
- modified built-in help to describe above features