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[RICH%MIT-OZ: ** New ZEmacs **]



The problem described in the following messages was determined to be a problem
with Teco/Emacs on VTS rather than a problem with ZEmacs only.  The solution to
this problem is to have Teco execute the following code as part of its startup
sequence:

	Movei	A,.CtTrm
	Rtmod%
	Tlo	B,(Tm%Scr)
	Stmod%

20-Jul-83 17:51:31-EDT,657;000000000000
Date: 20 Jul 1983  09:50 EDT (Wed)
From: Charles Rich <RICH%MIT-OZ at MIT-MC>
To:   Leonard N. Zubkoff <Zubkoff at CMU-CS-C>
Re:   ** New ZEmacs **

Leonard - Your new release seems to have the echo area default
size set to 2 instead of 3.  This would be a win (I tried it before)
except that some interaction bug between the Emacs and Twenex
(I think it has to do with a system call used in the echo area
printing a CR at the end that cannot be suppressed) causes the top
line of the display to be wiped out whenever a command like
C-X C-W is used.  Unless you can fix this bug, I am afraid you have
to change the default back to 3.

			-CR
20-Jul-83 21:14:44-EDT,1113;000000000000
Date: 20 Jul 1983  20:47 EDT (Wed)
From: Charles Rich <RICH%MIT-OZ at MIT-MC>
To:   Leonard N. Zubkoff <Zubkoff%TARTAN at CMU-CS-C>
cc:   Charles Rich <RICH%MIT-OZ at MIT-MC>
Re:   ** New ZEmacs **

Leonard -
   The problem I described is independent of your modifications to
Emacs, as far as I know.  I discovered it a long time ago when I tried
to shrink the default echo size area from 3 to 2 running on a local
terminal without Zemacs.  Apparently it is a well known Emacs-Twenex
screw.  If you know a way to fix it, I am sure that the Emacs hackers
here would be happy to hear it (the bug has been reported to them).
For now, the only fix I know is to change the echo area size back
to 3, as I now do in my Emacs init file.

			-Chuck.

P.S. I will almost swear that other people are experiencing this
problem but haven't reported it since it is intermittent.  It took
me several weeks to notice it myself back when I reduced my echo
area in Emacs to 2.  It only occurs when Emacs uses the Twenex
system call to get completing read of file names, as in certain
commands like C-X C-W.
21-Jul-83 01:49:08-EDT,1956;000000000000
Date: Thursday, 21 July 1983  01:49-EDT
From: Leonard N. Zubkoff <Zubkoff at TARTAN-20.TL>
To:   Charles Rich <RICH%MIT-OZ at MIT-MC.ARPA>
Re:   ** New ZEmacs **

Charles,

It seems strange to me that such a well-known Emacs-Twenex screw has never hit
me in over three years of almost exclusively using local terminals with two
echo lines on CMUC and TARTAN.  Let me see if we agree on exactly what's
happening.  At some point, one executes a command such as C-X C-W that does a
Comnd% parse of a file name from the echo area.  The entire prompt plus file
name fits on one line (right below the mode line), as in

Write File (Default PS:<ZUBKOFF>MAIL.TEMP.0): Foo.bar.5

and yet the CR somehow echoes in a manner that causes the top line of the
screen to (1) disappear entirely or (2) be cleared.  And this problem only
manifests itself on local terminals (not Chaos, for example).

Has this problem actually happened to you with the new ZEmacs and if so, is it
repeatable on demand?  If not on demand, does it happen at all consistently?
Have you ever seen the problem on other than a Concept-LNZ terminal?
Concept-HDS terminal?  Does this only happen on MIT Twenices, or have you seen
it occur elsewhere as well?  Does it only happen with WRAP mode, or with SCROLL
as well?  My suspicion is that MIT's WRAP mode, which is an extension to
Tops-20, is causing a CR or LF to automatically WRAP and clear the top line of
the screen when it shouldn't (that's why I need to know if the top line is
really cleared, deleted, or merely scrolled off the top but still present in
the terminal).  If you can give me a good idea what the conditions are that
make this happen, perhaps I will be able to find the problem, or come up with a
way around it.  As a last resort, there's going back to 3 echo lines, but to do
that right I'd have to re-build special versions of the screen managers with
that knowledge built in.

		Leonard
22-Jul-83 12:16:18-EDT,3800;000000000000
Date: 22 Jul 1983  12:03 EDT (Fri)
From: Charles Rich <RICH%MIT-OZ at MIT-MC>
To:   Leonard N. Zubkoff <Zubkoff%TARTAN at CMU-CS-C>
cc:   Bug-Emacs%MIT-OZ at MIT-MC, Bug-Exec%MIT-OZ at MIT-MC,
      Rich%MIT-OZ at MIT-MC
Re:   2 Echolines Bug

    Return-path: <Zubkoff%TARTAN@CMU-CS-C>
    Received: from TARTAN by CMU-CS-C with TLnet; 21 Jul 83 01:47:59-EDT
    Received: ID <ZUBKOFF@TARTAN-20.TL>; Thu 21 Jul 83 01:49:09-EDT
    Date: Thu, 21 Jul 1983  01:49 EDT
    From: Leonard N. Zubkoff <Zubkoff%TARTAN@CMU-CS-C>
    To:   Charles Rich <RICH%MIT-OZ@MIT-MC>
    Subject: ** New ZEmacs **

    Charles,

    It seems strange to me that such a well-known Emacs-Twenex screw
    has never hit me in over three years of almost exclusively using
    local terminals with two echo lines on CMUC and TARTAN.  Let me
    see if we agree on exactly what's happening.  At some point, one
    executes a command such as C-X C-W that does a Comnd% parse of a
    file name from the echo area.  The entire prompt plus file name
    fits on one line (right below the mode line), as in

    Write File (Default PS:<ZUBKOFF>MAIL.TEMP.0): Foo.bar.5

With echolines set to 2.

    and yet the CR somehow echoes in a manner that causes the top line
    of the screen to (1) disappear entirely or (2) be cleared.

I think the problem is that a second CR is getting generated
by the system call prompt in addition to the one that I type to
end the command in Emacs.

I am not sure of the distinction you mean.  It becomes blank.  The
rest of the screen is unchanged

    And
    this problem only manifests itself on local terminals (not Chaos,
    for example).

No, I can repeat the problem on C108 through dialup into hardwire
port, and on AAA through our Chaosnet terminal concentrator, and
on local hardwire AAA.

    Has this problem actually happened to you with the new ZEmacs and
    if so, is it repeatable on demand? If not on demand, does it
    happen at all consistently?

It is repeatable on demand with both standard Emacs, the old ZEmacs
and the new ZEmacs.

    Have you ever seen the problem on
    other than a Concept-LNZ terminal?  Concept-HDS terminal?

See above.

    Does
    this only happen on MIT Twenices, or have you seen it occur
    elsewhere as well?

I don't know.

    Does it only happen with WRAP mode, or with
    SCROLL as well?  My suspicion is that MIT's WRAP mode, which is an
    extension to Tops-20, is causing a CR or LF to automatically WRAP
    and clear the top line of the screen when it shouldn't (that's why
    I need to know if the top line is really cleared, deleted, or
    merely scrolled off the top but still present in the terminal).

**** Yes, I think you are right.  If I set TERM NO WRAP before I start
up the Emacs, then the problem goes away.  It also seems that if I
turn WRAP back on afterward, the problem does not come back, i.e.
Emacs caches this terminal parameters.  This suggests that the
solution might be just to fix this parameters in Emacs to always be No
Wrap, regardless of what the external environment is.  (P.S. I can't
stand scrolling in my exec.)

    If you can give me a good idea what the conditions are that make
    this happen, perhaps I will be able to find the problem, or come
    up with a way around it.  

Thanks, very much for your effort.  It would be nice to have the extra
line of editing space.

    As a last resort, there's going back to
    3 echo lines, but to do that right I'd have to re-build special
    versions of the screen managers with that knowledge built in.

Strange.  I reset echolines to 3 in my init file using the new
Zemacs on my C108 dialup, and it seems to work perfectly.

		Leonard

Chuck.
28-Jul-83 09:06:15-EDT,868;000000000000
Date: 28 Jul 1983  08:58 EDT (Thu)
From: Charles Rich <RICH%MIT-OZ at MIT-MC>
To:   Leonard N. Zubkoff <Zubkoff%TARTAN at CMU-CS-C>
cc:   Charles Rich <RICH%MIT-OZ at MIT-ML>
Re:   2 Echolines Bug

    From: Leonard N. Zubkoff <Zubkoff%TARTAN@CMU-CS-C>
    To:   Charles Rich <RICH%MIT-OZ@MIT-ML>
    Subject: 2 Echolines Bug

    Charles,

    I've just installed a new ZEmacs into which has been added code to
    set the terminal to scroll mode within ZEmacs.  Since I can't
    generate the problem, I'd appreciate it if you'd test this out and
    let me know it that solves the problem for you.

		Leonard

BINGO!  That does it!  Thanks a million.  By the way, could you
forward the solution to BUG-EMACS, so that we can reduce our
echolines to 2 locally also.  (I assume it is something that can't
be accessed through Teco).
				-Chuck.