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From: vanam@pttesac.UUCP (Marnix van Ammers)
Newsgroups: net.micro.amiga
Subject: Re: Mechanics of dropping DTR
Message-ID: <308@pttesac.UUCP>
Date: Fri, 17-Oct-86 00:43:15 EDT
Article-I.D.: pttesac.308
Posted: Fri Oct 17 00:43:15 1986
Date-Received: Fri, 17-Oct-86 06:06:05 EDT
References: <305@pttesac.UUCP> <257@hao.UUCP>
Reply-To: vanam@pttesac.UUCP (Marnix van Ammers)
Organization: Pacific Bell ESAC, San Francisco
Lines: 40

In article <257@hao.UUCP> hull@hao.UUCP (Howard Hull) writes:
>In article <305@pttesac.UUCP>, vanam@pttesac.UUCP (Marnix van Ammers) writes:
>>                    ... according to Wecker, the [VT100] program does
>> *not* leave DTR on.  So now I've found that this thing that I thought
>> was a feature, actually only happens under certain circumstances.  I'm
>> trying to isolate just when I get this feature.  For some reason I
>> could not get the feature to work at all last night (DTR kept going off
>> when I quit the program) but I swear, the night before it was working
>> just as I've said: DTR remained on...
>
>Ah ha... I had the same sensation of inconsistency about Wecker's VT100 and
>the behavior of DTR dependent interfaces.  I finally discovered that what I
>had done was to invoke another terminal program which doesn't reset DTR,
>quit that, and then fire up VT100.  I read somewhere that the serial device
>keeps a cumulative count of the number of devices that have requested use
>of the port.  Those that open the device properly increment the count, and
>those that close the device properly decrement the count.  If you have a
>program that fails to close properly when it quits, then the device count
>is already at least one when VT100 starts up.  Thus when VT100 quits, the
>count remains greater than zero and DTR remains asserted.

Howard is right.  Just last night I discovered that when I use
maxicomm first and then vt100, when I quit the vt100 program then
DTR remains ON.  Now I *think* (still need to check this out) that
no matter how many times I run maxicomm, DTR is always turned off
when I quit the program.  Something doesn't quite make sense there.
But no matter how many times I run vt100 after once having run
maxicomm, DTR stays on when I quit.

Since I like DTR to remain on most of the time (but not always!)
I guess I can run maxicomm first.  Seems like it must be possible to
come up with a tiny little program that will do this for me.  That
makes it also possible to have a configurable (via vt100.init) DTR
ON option.  At least so I think.

Marnix
-- 
Marnix A.  van\ Ammers
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