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Date:      Sat, 9 Dec 1995 08:44:03 -0600
From:      Rich Murphey <>
Subject:   Re: tw driver
Message-ID:  <>
In-Reply-To: <> (message from Gene Stark on Sat, 9 Dec 1995 02:21:11 -0500)

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|Date: Sat, 9 Dec 1995 02:21:11 -0500
|From: Gene Stark <>
|>I'm trying to get the tw driver to work but haven't had any luck.  It
|>won't detect the TW523 connected to the parallel port.
|>- Rebooted.  The probe repeatedly calls wait_for_zero(), which never
|>  finds the zero crossing signal.  Eventually it gives up.
|I assume the TW-523 is plugged in the wall, right? (first things first)

This symptom is similar to what I saw: pin 17 on my
parallel port was write-only, so when reading it the zero
crossing singal was ignored.

|>- Built a connector for the parallel port according to the directions
|>  on
|>  With one small modification: RJ-11 pin 1 (black) goes to both
|>  DB-25's pins 12 and 17.  The tw source code says it looks at pin
|>  17, but the web document mentioned above talks about 12 being
|>  preferred, while 17 is backwards compatible.
|The document you cite was written after FreeBSD 2.0.5, and it refers
|to a version of the tw driver that Rich Murphey worked on a few months
|ago, but which as far as I can see was never committed to FreeBSD-current.
|The version that is in FreeBSD-current does not have Rich's modifications,
|including the pin 12 stuff.  I personally am using the driver that
|is in 2.0.5 (and have been for a couple of years).  However, Rich was
|not able to get stuff working with the sync line on pin 17, and was
|forced to switch over to pin 12, with some modifications to the driver.
|Best would be if you can get Rich Murphey or Steve Passe to send
|you their copy of the driver.  I can probably dig one up out of my
|back mail files, but I don't know whether it would be the final version
|that they arrived at.  If you don't have any luck getting it from them
|mail me back direct and I will look for it.

I'll send you a copy of what I'm using.  It works with 2.1
and FreeBSD-stable.  It still needs to be cleaned up, etc.,
but it's fairly stable in that I haven't touched it in a
month and haven't seen any problems in that time.

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