RFC 472 (rfc472) - Page 2 of 2


Illinois' reply to Maxwell's request for graphics information (NIC 14925)



Alternative Format: Original Text Document



RFC 472        Reply to Request for Graphics Information      March 1973


with an IMLAC passively displaying the NGP0 pictures created.  Soon, I
hope to finish an IMLAC program that will handle some interaction with
the mouse/keyset.  I have decided to implement the following (outgoing)
commands.

    MOVE  beam to mouse position

    DRAW  from last to present beam position.

    TEXT  at present beam position.

    UNDO  the last command (to facilitate freehand drawing and
          backspacing in TEXT).

Other commands may be implemented as needed to do what people want to
do, at least until an adequate interaction standard comes along.

Note that there is implicit in the UNDO command the assumption that
the other end of the line possesses a certain amount of memory and
intelligence.  Two possible philosophies for standardizing interaction
are that (1) all "nodes" ("generators" or "users" of data) understand
some set of commands and possess at least a certain amount of
intelligence, and (2) a distinction is made between "displays" and
"computers" (quotes because the line is fuzzy).  I favor the first for
its generality, but I suggest that the lowest level of interactive
graphics might want to use the second for ease of implementation with
unintelligent devices, e.g., COMPUTEK 400's.  (I do not mean to
imply in (1) that the actual "computer" would not have a larger
vocabulary than the actual "display" --this is inevitable with higher
level capabilities in the protocol).

Since we have almost no local computing power for applications work,
all our graphics computation is done remotely (our work has been
primarily at UCSD (B6700), USC-ISI (TENEX), and UCLA-CCN (360)).
Because we do our work at scattered sites and are basically economic
of labor (pronounced "lazy"), we have a lot to gain by standards and
will be glad to cooperate as much as possible with standardization
efforts.

Steve Bunch




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Bunch