Browse Prior Art Database

Some historic moments in networking (RFC0089) Disclosure Number: IPCOM000006050D
Original Publication Date: 1971-Jan-01
Included in the Prior Art Database: 2019-Feb-11
Document File: 7 page(s) / 10K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

R.M. Metcalfe: AUTHOR

Related Documents

10.17487/RFC0089: DOI

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 20% of the total text.

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


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.


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 [Page 1]


Brodie, Knight, Metcalfe, Meyer, Padlipsky and Skinner) was commissioned to establish a ’polite conversation’ between a Multics terminal and an MITDG terminal.

It was agreed that messages would be what we call ’network ASCII messages’: 7-bit ASCII characters right-adjusted in 8-bit fields having the most significant bit set, marking, and padding. In that Multics is presently predisposed toward line-oriented half-duplex terminals, it was decided that all transmissions would end with the Multics EOL character (ASCII <LINE FEED>). To avoid duplicating much of the INCP in our experiment, the PDP-10 sid...