Re: Terminal Graphics Draft 2

From: Frank da Cruz (
Date: Thu Oct 08 1998 - 17:17:19 EDT

I neglected to answer this one...

> > Digital VT220 and higher terminals, as well as Televideo, Wyse, HP, Perkin
> > Elmer, and other models, allow the user to select whether control
> > characters are acted upon or displayed graphically. Unicode itself
> > includes its own ...
> Well, to my mind that indicates that these aren't NEEDED to be encoded at
> all! Just set the terminal emulator into the "display controls" mode and
> let it display the glyphs that the emulator has for the control codes.
Good point. Indeed, this character set, unlike others in the VT220 (and
higher) can not be selected by the host using ISO 2022 escape sequences, which
makes sense -- the familiar "transparent mode" conundrum -- once entered, how
then to exit, since everything is transparent?

However, this is not to say that other terminals, such as the Wyse 60, which
do not comply with ISO 2022 rules, do allow the host to command them into
"display controls" mode.

In any case, the control-picture symbols must be encoded because we're
concerned not only about the terminal emulator but also the applications it
must interact with, as in:

  User: "Help, my screen is messed up!"

  Help desk: "OK, click on Debug in the Terminal window menu bar
    and repeat what you did before."

  User: "Now my screen is REALLY messed up!"

  Help desk: "Let's have a look. Please use your mouse to copy it
    and paste it into your email window and send it to us."

This is, of course, looking forward to the day when All Is Unicode...

- Frank

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