[ih] The origin of variable length packets

[Noel Chiappa]

    > From: Stephen Suryaputra <ssurya at ieee.org>

    > Any pointer or reasons why the packet becomes variable length later on?

I would assume/guess that the first well-known and wide-scale use was in the
ARPANet. (Which was pretty much the first general packet network I know of -
were they any proprietary things before that, does anyone know?)

The first variable length data items transmitted between compturers (although
I would tend to doubt they thought of them as packets) might be hard to track
down.

It might have been some of the early computer-computer experiments, e.g. the
kind of thing Larry Roberts did at Lincoln Labs (which definitely had variable
length messages); another early system that might have had variable length
data items was SAGE (since that also had computer-computer links between
centers, although I don't know offhand of a source that talks about that level
of detail on the communication aspects of SAGE).


    > A reference would be really appreciated.

For Larry Roberts' work:

  Thomas Marill, Lawrence G. Roberts, "Toward A Cooperative Network Of
  Time-Shared Computers", Fall AFIPS Conference, October 1966

For the ARPANET:

  Frank Heart, Robert Kahn, Severo Ornstein, William Crowther, David Walden,
  The Interface Message Processor for the ARPA Computer Network (1970 Spring
  Joint Computer Conference, AFIPS Proc. Vol. 36, pp. 551.567, 1970) 

For SAGE, although there are a number of things about it, for instance the one
listed here:

  http://en.wikipedia.org/wiki/Semi_Automatic_Ground_Environment#Further_reading

Like I said, I don't know of anything there that goes into a lot of technical
detail on the communication stuff, though. (I looked through a couple,
including the 'Annals of the History of Computing' issue.) In particular,
there's a rumor that SAGE had the first email, but the communication part of
the system especially is so poorly documented in the open literature I've
never been able to track that down. There is a fair amount on the AN/FSQ-7
computer, and some on the programming, but the whole communication aspect
(other than the early radar data transmission) is seemingly not covered
anywhere.

	Noel