[comp.sys.apple2] Modem problem

THROOP@GRIN1.BITNET ("Throop,Henry B") (05/03/91)

Occasionally when I'm logged onto the VAX here, all lowercase letters I
receive from my modem are changed to one of a few symbols (~+._'`).  (For
example, maybe all a's, c's, and r's are changed to ~, etc.  I don't know
exactly what the translation is.)

Uppercase letters, numbers, and symbols (I think) are ok.  Sending characters
has no problems.  Rebooting doesn't fix this, nor does an ice-reboot
(reset from self test), but cycling the power does.  Some programs on the VAX
that reinitialize the terminal cure the problem when I'm online and run
that program, leading me to think it may be a serial port setting that is
getting messed up.

This mainly happens when spurious characters are received - eg line noise
or viewing binary file - which then puts me into this translation mode
thing.

Supra 2400 external, 8N1, gs modem port, Kermit or ProTerm.

Henry
--
Henry Throop
throoph@jacobs.cs.orst.edu
THROOP@GRIN1.BITNET

parkern@jacobs.CS.ORST.EDU (Neil Parker) (05/03/91)

In article <9105030354.AA14809@apple.com> THROOP@GRIN1.BITNET ("Throop,Henry B") writes:
>Occasionally when I'm logged onto the VAX here, all lowercase letters I
>receive from my modem are changed to one of a few symbols (~+._'`).  (For
>example, maybe all a's, c's, and r's are changed to ~, etc.  I don't know
>exactly what the translation is.)
>
>Uppercase letters, numbers, and symbols (I think) are ok.  Sending characters
>has no problems.  Rebooting doesn't fix this, nor does an ice-reboot
>(reset from self test), but cycling the power does.  Some programs on the VAX
>that reinitialize the terminal cure the problem when I'm online and run
>that program, leading me to think it may be a serial port setting that is
>getting messed up.
>
>This mainly happens when spurious characters are received - eg line noise
>or viewing binary file - which then puts me into this translation mode
>thing.
>
>Supra 2400 external, 8N1, gs modem port, Kermit or ProTerm.
                                          ^^^^^^
                                           A-ha!

This sounds rather like you've discovered the VT-100 line-drawing character
set.  Real VT-100's have a secondary character set consisting of little
line segments and wierd symbols, which can be used to draw pretty borders
around around the text.  Since the Apple II display doesn't have these
special line-segment characters, VT-100 emulators such as Kermit translate
them into characters that the Apple II can display--for example, in the
line-drawing character set a lowercase "x" is displayed as a vertical bar,
which the emulater translates into "|".  Similarly, a lowercase "n" is
displayed as a cross, and the emulator simulates it by displaying "+".

The problem occurrs when a spurious shift-to-line-drawing-mode command is
received by the emulator (usually due to line noise or an attempt to
display a non-ascii file).  The emulator immediately tries to start
translating lowercase letters into line-drawing characters (all the
line-drawing codes are lowercase letters--uppercase letters are unchanged),
even though that's not what you wanted, and you end up staring at a screen
full of gibberish.

I have no idea why the power switch would be the only way of correcting the
problem--I would think that simply exiting the program and restarting it
would be good enough.

There is a way to fix the problem that's much easier and less painful than
restarting the program or hitting the power switch.  On your VAX, create a
file with the following characters in it:

     Escape ( A Escape ) A control-N

("Escape" means the ESCAPE key, NOT the letters E, s, c, etc.  The spaces
in the above line are for readability only--they should NOT be entered
into the file.)

Then, when the problem strikes again, TYPE the file (if your VAX is
running VMS) or cat it (if it's running UNIX), and your subsequent output
should be magically restored to legibility.

You may be interested to know that this problem isn't limited to Apple II's
emulating VT-100's.  Every now and then somebody on our local VMS system
tries to type something like "PRINT/QUEUE=LP$CC105 FOO.EXE".  Since .EXE
files on VMS rarely consist solely of ASCII characters, this generally has
the effect of making the printer form-feed fifty pages at once and enter
Ancient Egyptian Hieroglyphics Mode.

>Henry

	       - Neil Parker
--
Neil Parker                 No cute ASCII art...no cute quote...no cute
parkern@jacobs.cs.orst.edu  disclaimer...no deposit, no return...
parker@corona.uoregon.edu   (This space intentionally left blank:           )