Aucbvax.5896
fa.info-vax
utcsrgv!utzoo!decvax!ucbvax!info-vax
Thu Jan 21 16:50:54 1982
Terminal drivers on Unix and VMS
>From decvax!duke!bcw@Berkeley Thu Jan 21 16:45:14 1982

This is in response to Terry Laskodi (ucbvax!teklabs!terryl)
discussing terminal drivers on VMS and Unix.  There are several
errors of fact in that article which I would like to correct:

1)  It is possible to change one's mode on VMS so that special
    characters are not processed.  It is also possible to turn
    off character echo, without special privilege.  It does
    require special privileges to be able to set terminal
    characteristics permanently so that all future users of
    the terminal will get those characteristics forever and
    ever amen.  This seems like a reasonable restriction.

2)  Although it isn't possible to change the meta-characters
    on VMS, it isn't always possible to do this under Unix
    either:  the \ character is an example.  This character
    can be extremely annoying, as there are times when it
    would be nice for the escape mechanism to go away so that
    it can be used as a normal character.

3)  The choice of turning form feeds into line feeds is not a
    bad choice -- the number is computed from the page size of
    the terminal and is done for the benefit of hardcopy output
    terminals.  You at least want the ability to turn form feed
    characters into something innocuous:  many terminals use a
    single form-feed character to mean screen clear.

4)  I'm not sure that you want a terminal driver which just
    dumps characters, even control characters, from the keyboard
    into a file.  At least there should be a way to turn this
    off -- it can be extremely annoying.  I have spent a lot of
    time on an OS (which shall go nameless, but I'm not thinking
    of Unix) which did just that, and when you tried to compile
    something you'd get lots of compilation errors ... and the
    offending characters were turned iwto ?'s.  Getting rid of
    them can be a real headache.  On the terminal which I had to
    use, generating extraneous control characters was just about
    the easiest thing in the world.

As far as terminal drivers go, I don't see much real difference
between Unix and VMS.  Both have some minor glitches and some
minor advantages, but both are much nicer to use than a lot of
software I've met.

			Bruce C. Wright @ Duke University

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