4. Dave Mills, the Network Time Protocol (NTP), its timescale and chronometry

posted Sep 20, 2010, 7:54 AM by Jeff Ogden   [ updated Jun 4, 2014, 7:02 AM ]
Dave Mills worked at the UM Computing Center in the late 1960s and early 1970s where he developed the PDP-8 based Data Concentrator and what was almost certainly the first non-IBM implementation of a S/360 control unit to I/O channel interface. After Dave left UM he went on to do many important things related to satellite and data communication and what would become today's Internet. Among his work is the design of the Network Time Protocol (NTP). NTP is used by pretty much every computer in the world that is connected to the Internet. In 2008 Dave was elected to the National Academy of Engineering for "contributions to Internet timekeeping and the development of the Network Time Protocol".

A Wikipedia article gives more information about Dave.

There is also a bio sketch for Dave in the People section of this web site.

Starting with the second NTP RFC the RFCs include a fascinating collection of information on time and dates that goes well beyond what is strictly necessary for the implementation of an Internet protocol. The information has been edited and reworked in each of the three NTP RFCs:

RFC 958 - Network Time Protocol (NTP), September 1985
    Does not include separate sections with timescale and chronometry information
RFC 1059 - Network Time Protocol (Version 1), July 1988
    See section "2.3 Time Scales"
RFC 1119 - Network Time Protocol (Version 2), September 1989
    See sections "2.3. The NTP Timescale", "2.4. The NTP Calendar", and "2.5. Time and Frequency Dissemination"
RFC 1305 - Network Time Protocol (Version 3), March 1992
    See "Appendix E. The NTP Timescale and its Chronometry"

And Dave has written a book:

Computer Network Time Synchronization: the Network Time Protocol, CRC Press 2006, 304 pp.
From Dave's description of his book:
Chapter 13 describes how we reckon the time according to the stars and atoms. It explains the relationships between the international timescales TAI, UTC and JDN dear to physicists and navigators and the NTP timescale. If we use NTP for historic and future dating, there are issues of rollover and precision. Even the calendar gets in the act, as the astronomers have their ways and the historians theirs. Since the topic of history comes up, Chapter 15 reveals the events of historic interest since computer network timekeeping started over two decades ago.

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