What does this really mean? "tty -s && stty istrip"

Shell Programming and Scripting
1

I am having hard time understanding what this really do to the environment? I do understand this part "tty -s && stty " but not "istrip"

 
# stty command is executed only if a tty is attached to the process.
# stty istrip : Strip input characters to 7 bits
tty -s && stty istrip

I am also having hard time understanding what many of the options associated with "stty" really work!?
Is there a tutorial or example based reference or a book that explain what all options for "tty" "stty" do clearly?
Here one of the man pages I am looking at -->

 
http://resin.csoft.net/cgi-bin/man.cgi?section=1&topic=stty
2 
stty istrip]

sets the tty driver to strip input characters to 7bit ascii. ASCII is formally defined as having only 7 bits. "8 bit" ASCII is sometimes called "extended ascii". istrip is used to force extended ascii into standard ascii. UTF-8 is an extended ascii encoding for some UNIX locale settings. SO if you want only 7 bit ascii "inside" the terminal, strip off the leading bit.

Most of the stuff in stty dates from a time when there were lots of very slow peripheral devices, like modems that ran at 50 baud. In other words, you can safely ignore a lot of it. I do not know of a reference for stty settings.

3

What exactly one would be saving by setting "istrip"?
[ memory space/CPU cycles/Modem baud speed ]

It feels like it is going to accept only non-extended ASCII characters i.e from 0-127.

If its really the "baud speed", my machine has this setting..
$> stty -a | grep baud
speed 38400 baud;

So there is no point in setting this on my machine right !?

I also wonder why anyone would still want to use character set [s]other than UTF-8 in this internet age!

4

You are probably using a psuedo-tty. A real tty like this is not going to work with unicode. Real tty's and the newer glass ttys like the vt-100 used ascii and its a 7 bit code. They might connect via 300 baud modem. 1200 baud if you're lucky. Transmitting all those bit-8's, which should be zero, over a slow serial connection was not very attractive. That's why we stripped them.

But decisions like that were made by a program called getty before the login program ever ran. The line of code you ask about seems goofy to me. It will have no effect on a psuedo tty and seems like a potential disaster on a real one. I would like to know what the author was thinking.