Graphics meeting report
RFC 282

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Network Working Group                                    M. A. Padlipsky
Request for Comments: 282                                    Project MAC
NIC: 8164                                               December 8, 1971

                        GRAPHICS MEETING REPORT

   The second Network Graphics Group Meeting was convened at the
   Stanford Artificial Intelligence Lab at 6:00p.m. Sunday, November
   21st.  (Attendees are listed in the Appendix.)  Jim Michener served
   as chairman, and I either volunteered or was volunteered to serve as
   recording secretary, with Karl Kelly's assistance in keeping notes.

   An agenda was agreed upon for the meeting, covering three major
   topics: 1) reports on the experiments which had been set up at the
   July meeting,  2) prepared talks by attendees who had general points
   to raise about Network Graphics, and  3) specification of a "first-
   pass" graphics protocol.  Before the reports were given, some general
   discussion was held on two important topics: the "context" problem
   (just how, in the Network sense, are graphics connections
   established, and who is supposed to do what for whom), and what might
   be called the "console types" problem (should there be a separate
   protocol for inherently static storage tube type devices and one for
   inherently interactive refresh type devices which have their own
   processors, or can we come up with some sort of continuous -- or
   layered -- single protocol which covers both).  Both points were
   noted as being necessary to keep in mind for the protocol
   specification phase of the meeting, an apparent consensus emerged
   that a single protocol would be preferable, and the reports on
   experiments were turned to.

REPORTS ON EXPERIMENTS

   RAND - UCSB

   Eric Harslem of RAND and Ron Stoughton of UCSB reported on their
   experiment, which entailed use of the UCSB On-Line System (OLS) from
   RAND Videographics terminals.  As demonstrated by a videotape which
   was shown, the experiment was successful.  An RFC describing the
   simple protocol they used is forthcoming.  As noted in their
   discussion and in the RFC, the experimental protocol is not being
   proposed as a Network standard.  In addition to using OLS from RAND,
   a subsidiary experiment tested the sensitivity of the hook-up to
   variations in the size of the allocations (in the Host-to-Host
   Protocol sense) given at the RAND end.  It seemed clear from the
   videotape of the same pictures being drawn at various allocation
   levels that larger allocations allow for noticeably smoother

Padlipsky                                                       [Page 1]
RFC 282                 Graphics Meeting Report            December 1971

   "drawing" at maximum allocation, the picture essentially appeared all
   at once, whereas at minimum allocation, NCP-NCP overhead was
   sufficiently large that the picture appeared a portion at a time.

   SDC - DMCG

   An experiment intended to input tablet data collected at MIT Project
   MAC's Dynamic Modeling/Computer Graphics Group's PDP-10 to a
   character recognizer package at SDC was reported on by Jean Saylor of
   SDC and Jim Michener of DMCG.  Problems ranging from
   hardware/software difficulties at both ends (and in the middle) to
   time zone-induced system availability conflicts retarded the
   experiment's progress, although some transmission of data has been
   achieved.

   ILLINOIS MULTICS

   Also plagued with problems was the attempt to drive a console at U.
   of Ill. from the Multics Graphics System.  This experiment was
   reported on by Jack Bouknight (Illinois) and Ed Meyer (Multics).  An
   NCP bug at the Multics end and a machine switch at the Illinois end
   combined to prevent the carrying out of the experiment.

   DIGRESSION

   During his report, Bouknight expressed concern as to whether the
   Network as a whole is as yet sufficiently reliable to support
   graphics work.  As the ensuing discussion focused on the frequent
   unavailability of a host other than Multics, I feel that it is within
   my province to draw the curtain of anonymity over it without
   prejudice.  However, I feel that mention of the discussion need not
   be suppressed as well, in view of the fact that most of the attendees
   shared Jack's concern.  The apparent consensus, reached after
   considerable conversation, is that the present reliability level of
   the Network server hosts is not crippling to graphics work, but can
   be quite hampering.

   SEX - NIC

   Jon Postel (UCLA) and John Melvin (SRI) gave the last experiment
   report, on an attempt to make an IMLAC on the SEX system look like a
   local NLS console at the Network Information Center.  The experiment
   has not yet been performed, but UCLA has ordered the necessary
   equipment to modify their IMLAC.

Padlipsky                                                       [Page 2]
RFC 282                 Graphics Meeting Report            December 1971