new LISP rubout processing

[EKILLIAN at BBNA]

    Date: Tuesday, 28 October 1980  07:08-EST
    From: JONL at MIT-MC (Jon L White)

        Date: Monday, 27 October 1980  17:08-EST
        From: EKILLIAN at BBNA

        Doesn't seem to work when using SUPDUP to get to XX as opposed to
        TELNET.  Perhaps 20X is not setting the bit saying you can move
        the cursor backward on a SUPDUP terminal (because there is no %TD
        code for doing it -- you only have %TDMV0 and %TDFS)?  

    LISP only copies what VTS can do, and it seems likely that your analysis
    is right (i.e., no TC%MOV capability) which would mean no CURSORPOS
    capability of any note.  Also, no TC%SCL (or TC%CLR) would mean that
    the terminal can't selectively erase, so LISP wouldn't try the  rubout
    processing.  As for the echoing of ^L as a sail char, I'm not sure
    I understand what is happing wrong.

Rather than speculate further, I decided to find out what was
going on.  LISP is looking at TC%CLR and using that to set %TOERS
in one of its internal capability words.  It does not appear to
be looking at TC%SCL for that.  Also, 20X is not setting TC%CLR
on a SUPDUP TTY.  Why?  SUPDUP TTYs certainly use %TDCLR.
Anyway, it seems like both LISP and 20X are in error.