Re: supdup protocol

Barry Margolin (
13 Oct 87 20:11:45 GMT

In article <8710121554.AA07611@armagnac.DEC.COM> "Christopher A. Kent" <> writes:
>Some work was done a number of years ago (I can't find a reference, but
>it was at Arizona) to investigate how to use a micro to do editing
>across a 1200 baud link.

I don't think this is the exact paper you are talking about, but it is

Judd, J. Stephen, Corinne J. Letilley, "Memory and Communication
Tradeoffs During Screen-Editor Sessions", Univ of Saskatchewan, August
16, 1984.


   Screen Editor sessions typically make heavy use of the
communication channel between processor and display screen. This is
because relatibely simple and quick operations like window movements
can cause the transfer of 1000 or more characters. To get a
quantitative measure of communication requirements, we need to
determine how people use such systems. We accumulated a
representative sample of user activity by tracing the movements of the
cursor during 1500 editing sessions. Some information about these
sessions is presented.

   To make effective use of an interactive screen editor, the two-way
channel between the computer and the screen terminal must have a
fairly high baud rate. By simulating the observed sessions at various
baud rates, we measured the amount of time lost during such a session
if the baud rate is low. Then we estimated the increase in
performance afforded by keeping a buffer of text lines local to the
terminal. Resultant graphs are suitable for comparing the performance
of terminals with various memory sizes and baud rates.

   We prpose a terminal that takes an active role in the management of
text during editing sessions and we estimate its impact on CPU demands
in the host. This work has implications for the design of terminal
hardware and screen-editor software.

Barry Margolin
Thinking Machines Corp. seismo!think!barmar

This archive was generated by hypermail 2.0b3 on Thu Mar 09 2000 - 14:39:35 GMT