RFC 89 (rfc89) - Page 1 of 7

Some historic moments in networking

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Network Working Group                                        B. Metcalff
Request for Comments: 89                                           MITDG
NIC: 5697                                                19 January 1971


                  SOME HISTORIC MOMENTS IN NETWORKING

   While awaiting the completion of an interim network control program
   (INCP) for the MIT MAC Dynamic Modeling/Computer Graphics PDP-6/10
   System (MITDG), we were able to achieve a number of 'historic moments
   in networking' worthy of some comment.  First, we were able to
   connect an MITDG terminal to a Multics process making it a Multics
   terminal.  Second, we successfully attached an MITDG terminal to the
   Harvard PDP-10 System thereby enabling automatic remote use of the
   Harvard System for MIT.  Third, we developed primitive mechanisms
   through which remotely generated programs and data could be
   transmitted to our system, executed, and returned.  Using these
   mechanisms in close cooperation with Harvard, we received graphics
   programs and 3D data from Harvard's PDP-10, processed them repeatedly
   using our Evans & Sutherland Line Drawing System (the E&S), and
   transmitted 2D scope data to Harvard's PDP-1 for display.

The IINCP

   Our experiments were run on the MITDG PDP-6/10 using what we have
   affectionately called our 'interim interim NCP' (IINCP).  Under the
   IINCP the IMP Interface is treated as a single-user I/O device which
   deals in raw network messages.  The software supporting necessary
   system calls includes little more than the basic interrupt-handling
   and buffering schemes to be used later by the NCP.  In short, the
   user-level programs which brought us to our historic moments were
   written close to the hardware with full knowledge of IMP-HOST
   Protocol (BBN 1822).  When the INCP and NCP are completed, these
   programs can be pruned considerably (80%).  The exercise of writing
   programs which conform to IMP-HOST Protocol was not at all wasted.
   Only now can those of us who are not writing the NCP begin to grasp
   the full meaning of RFNM's and their use in flow control.  The
   penalties for ignoring an impatient IMP, for failing to send NOOPS
   (NO-OPS) when starting up, and for blasting data onto the Network
   without regard for RFNM's are now well understood.

The Multics Connection

   Our quest for historic moments began with the need to demonstrate
   that the complex hardware-software system separating MITDG and
   Multics was operative and understood.  A task force (Messrs. Bingham,





Metcalff
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