I've been giving MS-DOS Kermit a try lately, and since it will emulate
vt220 and vt320 (in addition to vt100), I figured, why not try out
vt220 or vt320 for a change?  The results I got were sufficiently
annoying.  I use the tcsh shell, but entering a 'setenv TERM vt220'
at the command line gives this result:
 
tcsh: No entry for terminal type "vt220"
tcsh: using dumb terminal settings.
 
Not what I wanted...  Okay, let's try vt320... 'setenv TERM vt320'
Hmmm, the system likes that one, now let's use vi...
 
/home/kentn> vi
vt320: Unknown terminal type
Visual needs addressable cursor or upline capability
 
A bit of poking around in /etc/termcap and /usr/lib/terminfo showed
that a number of vt320 definitions exist in termcap, but not in terminfo.
vt220, however, can be found in terminfo but not in termcap.  I can't
say for sure, but it looks like some applications look to termcap and
others to terminfo (tcsh vs vi, for example). 
 
Can anyone explain why I'm having this problem?  How can I use vt220
or vt320 and not have these conflicts?  Why aren't termcap and terminfo
"synchronized" in terms of the terminal types they support?

19 responses total.

I'll add that my .login has the following lines pertaining to terminals:

setenv TERMCAP /etc/termcap
setenv TERM vt100

I've heard that on this system, vi uses terminfo and everything else
uses termcap.  That's rather surprising -- on every other unix system
I've used that has termcap as its primary terminal description database,
vi uses it.

The main reason termcap and terminfo aren't in sync now is that the
Sun-2 didn't have terminfo, and over time we added a number of custom
terminal descriptions (several of them written by me) to the termcap
database on the Sun-2; vt320 was one of these.  They were all copied
over to the Sun-3, but of course the equivalent terminfo descriptions
didn't exist.  So vi can't use any of the new terminal descriptions we
installed until somebody takes the time to sit down and write terminfo
equivalents for all of them, a rather time-consuming process, or unless
there exists termcap-to-terminfo translation software that someone can
point us to.

I've never dealt with terminfo before, but I understand that writing and
installing a terminfo description is more involved that termcap --
the syntax is more elaborate, and there's an extra "compilation" step of
some sort.

Having to maintain two terminal description databases, each with its
own unique syntax, is a pain in any case.  A better solution would be
to replace the current vi with a version that uses termcap, if that's
feasible (I suspect it might not be), and forget about terminfo entirely.
There are a number of freeware vi clones available now, so that might be
one avenue to investigate.

Actually, I disagree here John. Terminfo is the more modern system and
termcap is going away. If we replace anything, it should be the things
that use termcap, but there's too many of them.

I can create the necasary terminfo files, there's a "captoinfo" program
that will do the translation.

I've been wanting to ask you about the SUn-2's termcap. Apparently, you
did alot of the changes in that file. Did you keep a record of what entries
you added or what you fixed? I would like to get rid of the old Sun-2
termcap and go to the Sun-3 termcap from the distribution tapes, but I
need to know what we added/changed first. I'm also trying to find a "virgin"
SunOS 3.5 Termcap to diff against ours.

Right -- it might be preferable if everything used terminfo, but
that's not practical for us now, as you point out.

I wonder how good the terminfo database is on this system.  I'm using
vi with my term set to "vt102", and vi is doing character inserts and
deletes the "slow" way, repainting the line character-by-character to
the right of the insert/delete point.  But the VT102 terminal has
"insert mode" and "delete character" commands that can do these
operations much faster, and vi's on other systems take advantage of
that.  So I'm wondering if the problem is that we have a brain-damaged
vi or if it's that the terminfo description for vt102 isn't all that
hot.

As far as I know, no existing entries in the Sun-2 termcap file were
changed.  A number of new entries were added; all the additions should
be documented as comments in the termcap file itself.  If you can give
me access to a copy of the Sun-3 termcap file, I'm willing to do the
work of deriving a new termcap file from it that's in sync with our
changes from the Sun-2.  And now that I know that there's a "captoinfo"
program, I'd be willing to update the terminfo database too.

John, the termcap file lives in /usr/share/lib on the Sun-3. The original
virgin hot-off-the-distribution-tapes version is called termcap.411.
The termcap in that directory is the one from the old Sun-2 with our 
changes. You should have access to those files as staff, if not just do it
as root. Don't change the termcap.411 file.
Thanks

Okay, I'll have a look.  Thanks for the info, er, cap.

I hope you get it figured out, John.  I'm kind of getting to like the
way vt220 works with trn (better than vt100 anyway).  It'd be nice if I
could use it here, especially if it would improve the speed of vi and
similar programs.

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Oh, I know how to use Kermit's funky terminal types.  They work fine
on the system at work (which is why I'm starting to prefer vt220 to vt100).
I'm just having trouble here on Grex.  Note that both vt220 and vt320
are available on Grex, but in a schizophrenic fashion (that is, they are
available, just not useable with all applications, and are in two different
places, termcap and terminfo).  
  This is probably another of those startup bugaboos that will get worked
out with time and a bit of effort (I hope).  The Sun Sparc 10 I use at
work has no problem dealing with both termcap and terminfo on the same
machine, so I don't think that's the problem.  I'll leave it to the
resident gurus to sort it all out.  For now, I'm surviving with vt100,
and still entering responses ;)

You'll probably see some improvement if you switch to vt102.

I would appreciate it if someone would post a table of the essential
features of vt-100 and up - perhaps describe these for vt-100, and then
tablulate the changes thereafter. I throw this jargon around, without
knowing what I'm talking about.

I have the information here and there; might take me a bit of time to
put it into table form, though.

A significant difference between vt100 and vt102 is that the latter
can do character insert and delete within a line.  That is, vt102 has
an "insert mode" such that when the cursor is in the middle of a line
and you type a character, the part of the line following the character
is pushed to the right "instantaneously".  Likewise, it has a "delete
character" command which moves text to the right of the cursor left
one space.  The vt100 does not have these features.

A text editor can take advantage of these features to improve its
screen updating performance.  Vi and emacs do this.  Of course,
advanced terminal features make no difference if the software does
not use them.

(For those who care but haven't had to deal with this before: with such a
feature, the program can send one character (or sequence) to go into insert
mode, and then the inserted characters.  Without it, the program must send
an inserted character followed by all the rest of the characters in the line,
then the next inserted character followed by all the rest again, then ...
at 2400 bps you get the idea.  At a really slow baud rate, say 300, you can
actually see this happen one character at a time, & it gets tiresome really
quick - you stop inserting & retype the whole line, every time.)

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That's a good field fix, cool.

Is vt320 any more useable now than in 1994? Have any problems
cleared up since then? I sometimes login with Kermit which
has vt320.

Should be okay now. I updated the terminfo database a while ago to
bring it into sync with termcap. In particular, vt320 should now
work with everything. If you try it and find that not to be the
case, please let me know.

This response has been erased.

There should be two terminal packages on this system, the "bsd" version
that uses termcap, and the "system 5" version that uses terminfo.  The
terminfo support is more complete and supports more terminal attributes
and a generally richer enviornment.  The lynx version that I compiled
for here uses the system 5 terminfo - but it's a minor pain to get the
right include files & libraries to make everything work right.

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