Table of contents
Brief bio, etc.
Involvement with the IEEE and IEEE Computer Society
Writings, biographical information, etc., on Internet history and computing
Other activities of mine
For family, friends, xBBNers, ...
My other websites
Brief bio of me, BBN, and Internet
After 27 years, I retired from Bolt Beranek and Newman Inc. (BBN) in 1995.
I had joined BBN in 1967 after three years at MIT Lincoln Laboratory
and, except for a year in 1970-71, spent the rest of my business career
with BBN, first as a computer programmer, then as a technical manager,
and then as a general manager. At BBN, I had the good fortune to be involved
in the beginnings of the Internet.
Over the next four years, after my retirement from BBN, I spent a little time with the
Center for Quality of Management
(CQM) and a little time with the
for Manufacturing Program at MIT.
The CQM web site included
of what I looked like as of a few years ago and other information
relating to my participation in the CQM.
These days I
mostly look out the window at the salt marsh near my home.
Looking out the window from our kitchen
Click for view from outside dining room window
Click for view of front of house (away from marsh)
In 1998 I was pleased to be named to the
hall of fame of my undergraduate college,
San Francisco State, for having been involved in the early days of the Internet. My
friend and classmate
Stan Mazor who was co-inventor of the micro-computer
went into my college hall of fame at the same time. (I love being on the same list
as Annette Benning and Danny Glover, among others see full SFSU Hall of Fame
list; I'm also listed with other notable alumni (under category 2 -- Science and Technology); and I was mentioned in SFSU Magazine, Vol. 1, No. 2, Spring 2001.) Then, in May 2014, Stan and I received honorary Doctor of Science degrees
at SFSU's undergraduate graduation ceremony.
about the early era of the Internet when I was involved can be
found in the following books:
In August 1999, the IEEE announced
that BBN Technologies had been awarded a
IEEE Corporate Innovation
Recognition: For pioneering contributions to computer networking technology
through the development of the first packet switches, the ARPANET Interface
Message Processor (IMP) and Terminal Interface Message Processor
(TIP). This work was done by a team of engineers and
scientists which I had the great fortune to be part of. (Click here
for copies of the widely published photos of the BBN team I was part
of, and click here for a more close up view of the IMP and team leader Frank Heart.)
In 2001, the Boston History and Innovation Collaborative honored BBN (and our
ARPANET team) and did it again in 2007: click here for more
My book Four Practical Revolutions in Management has been included on the Nippon Foundations's list of 100 Books for Understanding Contemporary Japan.
[It appears that I have an Erdös number of 4, if one ignores the fact that some of the connecting papers had more than two authors and the fact that two of the papers are more about computer communications than math. The sequence is Erdos-Mullin-Cerf-Kahn-Walden.]
[Note: Much of the information
in the conventional and business press about
my career since my time as a programmer on the BBN ARPANET team is
inaccurate; anyone including something on me in a piece you are
writing might query me directly rather than trusting what has been
written in the past.]
Over the years, I have written extensively on management topics.
Much of my effort in this area was through my affiliation with the
Center for Quality of Management and, more recently, my affiliation with the Confederation of Indian Industry:
The book A New American TQM
The book Four Practical Revolutions in Management
The book Breakthrough Management
The book Visionary Leaders in Manufacturing
The Journal of the Center for Quality of
Unpublished, to-be-published, and miscellaneously published papers
I have also written many technical papers, primarily related to my
involvement in computer networking. As time permits or I find them
already on the WWW, I'll post them to this web site or link to them. More
recently I have been doing a lot of writing on the TeX typesetting system.
- The original paper on the ARPANET IMP.
- The ARPANET
Design Decisions, by John McQuillan and me, Computer Networks, Vol. 1, No. 5, August 1977.
- RFC 62: A
system for interprocess communication in a resource sharing computer network
- A System for
Interprocess Communication in a Resource Sharing Computer Network,
Communications of the ACM, vol. 15 no. 4, April 1972, pp. 221-230.
- paper on host-to-host protocols published in 1975; the content was first presented at a conference which might have been a year earlier (I can't remember)
- Preprint of article by Alex McKenzie and me, eventually published as
"The ARPANET, the Defense Data Network, and the Internet," Encyclopedia of
Telecommunications, Marcel Dekker, Inc., Volume 1, pp. 341-376. This draft is from 1989 at a time when TCP/IP was not yet so dominate a communications protocol.
- A Note on
Communications of the ACM, vol. 15 no. 4, April 1972, p. 275.
- RFC 65: Comments on Host/Host Protocol Document #1
- User's Guide to the Terminal IMP, July 1977 revision (original written in 1971); for a few years I updated and maintained this document.
- "RFC 333: Proposed Experiment with a Message Switching Protocol" (with R.D. Bressler and D.
Some notes relating to the Telnet protocol
Bernie Cosell conceived the symmetric will/won't/do/don't approach to protocol design (see items 1, 2, and 5 below) in the context of the broad effort by many people to come up with an official Telnet protocol. Read the papers cited in the first and third items below and read the first group of RFCs under item 4 below to for lists of these people and the issues they were thinking about.
- RFC 435: Telnet Issues (Bernie Cosell and Dave Walden), January 1973
- During a 2012 discussion on the Internet History discussion list, Bernie Cosell stated the following (July 1, 2012):
From my work on the TIP I was already thinking a bit
about making Telnet symmetric. What I was mostly grappling with was if
the protocol were symmetric it could "loop" -- if commands passed each
other over the net, then the responses passed each other, and those
kicked off other responses, etc. One [loop] that came to mind (that I recall
thinking about back then) was with one end saying "I'll send echoes" and
the other saying "I'll echo locally". They cross, and each then responds
"OK you echo". Each now has gotten a change of state [since each said
they weren't going to echo and now has been told to] and so each sends
another "OK I'll send echoes" and "I'll echo locally" and around they
My actual goal in the sketching on the napkin on the plane flight [and I
remember mentioning it to Dave, sitting next to me, and waving my hands a
lot] was "Look: if the commands are will/wont/do/dont and the rules
follow state diagram, then it can't loop and will always end up in
a reasonable state [just not-looping wasn't enough, of course, lest the
connection end up with BOTH ends thinking that the other is echoing, or
Another important idea that it handled was that it was
extensible: it provided for the notion that one side could ask about
something unknown and that'd be OK [and the negotiation would do the
right thing], so there could be fancy-hosts and not-so-fancy ones and
they could negotiate to make as clever a connection as they could while
still gracefully handling hosts that could only deal with not-so-clever
- The ARPANET Telnet Protocol:
Its Purpose, Principles, Implementation, and
Impact on Host Operating System Design (Davidson, Hathaway, Postel, Mimno, Thomas, and Walden), 1977, a historical look back at the evolution of Telnet
- Section 2 of the prior paper (item 3) contains a history of the evolution of Telnet. At the end of the paper is the following list of RFCs relating to the evolution of Telnet:
- RFCs on New TELNET Design and Specification: 357,
426, 435, 461, 495, 513, 529, 559-560, 562-
563, 581, 587, 595-596, 651-659, 671, 698,
- RFCs on New TELNET Implementation: 559, 593, 669,
678, 688, 701-703, 718.
- RFCs on Old TELNET Design and Specification: 1 5 ,
97, 109-110, 1 3 7 , 139, 1 5 8 , 295, 318, 328,
- RFCs on Old TELNET Implementation: 206, 216, 452,
- RFCs on Satellite Considerations: 346, 355.
- Developing Telnet’s negotiated options (Bernard Cosell and David Walden), 2003, a historical look back at Bernie's conceiving of Telnet's negotiated options.
- My presentation on the ARPANET to the 1972 AFCET conference in Paris
- Gateway design for computer network interconnection, by Randy Rettberg and me, Proceedings of Eurocomp 1975, The European Computing Conference on Communications Networks, London, England, September 23-25, 1975, pp. 113-128
- RFC 636: TIP/TENEX
Reliability Improvements (J.D. Burchfiel, B. Cosell, R.S.
Tomlinson, and D.C. Walden), June 1974
- Techniques for Detecting and Preventing Multiprogramming Bugs, by Bernie Cosell, John McQuillan, and me; Minicomputer Software, J.R. Bell and C.G. Bell (eds.), North-Holland Publishing Company, 1976.
- A bibliography of BBN's Internetworking papers that I helped produce in 1994
Technical writing on my "travels in TeX land"
Over the past several years I have published a number of pieces on
my on-going experiences while learning and using the TeX typesetting system.
I have given this its own web page:
That page also has links to other TeX-related activities of mine, including an interview series (including an interview of me conducted by Karl Berry).
A fairly complete list of my published technical (and management)
writings is included in my CV
- Published books
Involvement with and writing and editing for the IEEE and IEEE Computer Society
Since I retired from BBN, my involvement with the IEEE and IEEE Computer Society has become significant.
This activity has its own webpage.
Musings on the history of the Internet and my
computing experiences more generally (and related biographical
- Interview relating to the
beginning of the ARPANET, on file at the Charles Babbage Institute
(Center for the History of Information Processing), recorded 6 February
1990: after clicking on this link, scroll down the page and click
on "Walden, David C.", and then scroll down the page and click on "link
- Interview of me by Karl Berry for the TeX User Group's interview series (2006)
- My MAPS interview by Frans Goddijn (2006); this interview is sort of a successor interview to the prior (TeX User Group) interview
- Another ARPANET
related interview done by the Computer History Museum in 2009
- 2014 interview by Brad Fidler and Len Kleinrock of UCLA
- Computing memoir for the IEEE Global History Network First-Person website (this
memoir covers in one place information already in several of the following notes)
San Francisco State University College of Science and Engineering
Alumni Newsletter (Fall 1998)
- How I stumbled into being
involved with the beginnings of the Internet
- On my first years
of work, at Lincoln Lab and BBN with Frank and Will
- On my first two
years of "work" at BBN, before I got involved in the ARPANET
- Observations on
the beginnings of the Internet
- Preface for
publication of the early BBN Quarterly Technical Reports on the ARPANET
- Reflections on the 25th
anniversary of the Internet
- On the rest
of my years of "work" at BBN
- On losing computer
- Some history of the
original ARPANET routing algorithm and what it is called today
- Looking back at the ARPANET effort, 34 years later
- Some Observations and Interpretations of Internet History from 1968 to 1980 -- part of A Technical History of the Internet (an ACM SIGCOMM Tutorial given by 19 voices, speaking for a much larger community) at SIGCOMM 1999, 31 August 1999, Cambridge MA, USA
In June 2004 I visited briefly with Internet pioneer Louzin Pouzin in Paris.
- I gave a presentation on the history of the
Internet at the Polyteknisk Foreninghttp in Oslo on September 18, 2007. Also presenting
were Robert Cailliau (co-inventory of the World Wide Web) and Håkon Wium Lie (CTO of Opera Software
and inventory of Cascading Style Sheets for HTML).
Some other activities of mine
Over my life I have moved serially through a number of hobbies, each
one intense for a time, for example, contract bridge, amateur theater,
postal chess, juggling, sail boating, and celtic traditional music.
Ive never gotten super good at any of these, but Ive had a
good time. Click here for photos relating
to the last three of the above list.
Following are links relating to (a) about my only current heavy-duty recreation, movie going, and (b) what seems to be my current avocation, writing and self-publishing (there is also a sacred activity—watching Red Sox baseball):
For my family, friends, xBBNers
I have posted on this web site some documents that I prefer not to display to
the public at large, because they include names of other people, etc. If you
try to access these documents, you will be asked for a userid and password;
the username is the letter a and the password is the letter b. Please do
not include public links to these documents.
- About the Schoolhouse (our condominium building in Boston)
- Our trip to East Africa in 1994
- Sailing race to Bermuda in June 2001
- Our month in Mexico in October 2001
- Our two weeks in Italy in March 2002
- Our son and daughter-in-law's September 2002 wedding
- Sail to Antigua in October 2002
- Our two weeks in Brazil in October 2003
- Our nearly three weeks in Paris and Norway in June 2004
- Two weeks along the east coast of Florida in January 2007
- Ten days in the vicinity of Nice, France, in April 2007
- Dave's quick trip to Oslo in September 2007
- Our ten day visit to Norway in May-June 2008
- A week long business trip to Mumbai, India, in September 2008
- A week trip from Portland, OR, to Vancouver and Victoria, BC, in April 2011
- Driving across the country from Portland, OR, to Cape Cod, MA, in May 2011
- Three week trip to New Zealand in March 2013
- Obsolete: Collected thoughts on health insurance when not part of a large group plan, exchanged by xBBNers
- Obsolete: Collected thoughts on Long Term Care insurance, exchanged by xBBNers