Date   : Wed, 28 Mar 1984 10:59:00 MST (Wed)
From   : Keith Petersen <W8SDZ@Simtel20.ARPA>
Subject: modem7 and emacs

There is an option byte in all the MDM7xx overlays which allows you to
"filter out" all control characters below Line Feed.  That's nice for
eliminating phone line noise-induced garbage, but plays havoc with
cursor addressing when using mainframe video-oriented text editors.
Turn the option off in your overlay and things will work right again.
--Keith