[Info-vax] VTxxx/VMS term driver: bug or feature?

[Johnny Billquist]

On 2011-06-30 16:44, VAXman- @SendSpamHere.ORG wrote:
> In article<nCPQG4dCMxfn at eisner.encompasserve.org>, koehler at eisner.nospam.encompasserve.org (Bob Koehler) writes:
>> In article<iuhlkv$lt4$1 at Iltempo.Update.UU.SE>, Johnny Billquist<bqt at softjar.se>  writes:
>>>
>>> So a "strange thing" is not a bug?
>>
>>    What the real terminals do, is something I would consider a bug.
>>    That is, the text displayed is not the text I would expect from the
>>    documentation that I've read.
>>
>>    An emulator should act like the real thing, but I can understand
>>    allowing the user to turn on/off bug compatability.
>
> The real VT displays the text, in my example program, as I'd expect to see
> it when SET TERMINAL/NOWRAP and local wrap conditions have been established.
>
> The odd thing is when the terminal driver is asked to implement wrap when
> the terminal is set not to locally wrap.  This oddity seems to appear on
> all of my VT terminals and DECterm, even though I don't consider the VMS
> terminal driver's handling of the wrap case correct.  Stranger, not really,
> is that a particular terminal emulator doesn't display this oddity.

I'd say this has very little to do with the terminal emulation and a lot 
to do with VMS terminal driver wrap implementation.
The only thing terminal related is how the terminal behaves when not 
wrapping, sitting at column 80, and you output a character. Most every 
terminal emulator seems to think that the character should be discarded, 
since you're outside the screen. A real VT100 affects column 80 again, 
even though the cursor is logically at column 81.

So you get either '00' at the right end (the correct result) or '01' at 
the right end (the wrong result). I know that putty does a lot of wrong 
at this point as well, which is part of the gripe I have with putty. If 
you are at column 80, output one character, and sends a backspace, putty 
will remain at column 80. :-(

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol