Symbolics terminal emulator works lousy

[Barry Margolin <barmar@think.com>]

    Date: Thu, 17 Dec 87 11:05 EST
    From: Daniel L. Weinreb <DLW@alderaan.scrc.symbolics.com>

    I just tried it (Telnet to Unix via IP/TCP, simulating an Ambassador)
    and it worked fine for me.

Perhaps things are better in the development system (I assume that is
what you are using, Dan, and I've heard that Terminal was rewritten to
use dynamic windows, so maybe the emulation was improved in the
process), but the terminal emulation in the released system is lousy,
and hasn't changed for several releases.  The code that processes ANSI
control sequences has some implicit assumptions about the relationship
between the sequences CSI <char> and ESC <char> (basically, if the CSI
handler doesn't recognize the <char> the code falls through to the ESC
handler, or maybe it's vice versa).  ASCII LF is translated into
newline/clear-line, which causes random lines to be cleared if a host
likes to use LF for its standard meaning of "move the cursor straight
down" (the Multics Ambassador terminal description uses this).  I had to
patch this to make Telnet to Multics usable.  Customizing the emulator
is a real pain because it is implemented using lots of CASE statements
rather than tables, so we have to redefine a bunch of Symbolics
functions.

                                                barmar