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Re: Tab vs. Supdup
- To: CPH@MIT-OZ, GZ@MIT-OZ
- Subject: Re: Tab vs. Supdup
- From: John Wroclawski <JTW@MIT-SPEECH>
- Date: Sat 18 May 85 13:55:52-EDT
- Cc: Bug-EMACS@MIT-OZ, Bug-OZ@MIT-OZ
- In-reply-to: Message from "CPH@MIT-OZ" of Tue 7 May 85 18:16:40-EDT
Hmmm, I guess I never got around to sending this before...
Subject: Tab vs. Supdup
Date: Tuesday, 7 May 1985 15:45-EDT
From: Gail Zacharias <GZ>
Thanks for the advice; I will write a program to call STCHR% and set
things up correctly.
You will also have to deal with the STMOD% jsys, see below.
The problem is that when I use a dialup, I'm only getting 7 bits
transmitted to me (apparently with even parity). The supdup codes
come get transmitted by OZ, but when I get them some of them don't
have the eighth bit turned on.
DEC has the interesting idea that the whether or not parity is needed is
determined by the *line type* (i.e. hardwired, chaos NVT, PTY, etc.),
rather than by either the terminal type or a combination of the terminal
and line type, which would be correct. Chaos NVT's don't add parity.
Hardwired (incl. dialup) lines do, unless they're in binary mode. I
guess it's time we designed a fix for this.
The other problem about the supdup input escapes is that when I send
^\ (octal 034) to OZ, nothing special happens; so none of the supdup
escape sequences can be used. Will STCHR% fix this too?
There are two VTS jsyi of interest, STCHR% and STMOD%. STCHR is for
telling the system about hardware-dependent characteristics of the
terminal, such as whether it can scroll or insert and delete lines.
STMOD is for making a choice among various different modes of terminal
operation that the system can support, such as wrap vs. scroll and how
end-of-page indications are presented. In the normal supdup case of
connecting over a net, both of these words are set by the server that
does the initial connection. To use a hardwired line you will have to
set both yourself.
To turn on ITP you have to set the TM%ITP bit using STMOD%. I don't
know why it's a mode, it seems more like a STCHR% characteristic to me.
Anyway, this will cause ^\ to work as the escape character for sending
bucky bits, etc. *However*, the implementation is incomplete - in
particular the flow control part of ITP is not there, since it is not
used for network terminals. Adding it would be moderately tricky;
were you planning on using it? Also Twenex's handling of output
resets (%TDORS) isn't quite right, but that needs to be fixed
pretty badly anyway.