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From: veit@mururoa.gmd.de (Holger Veit)
Subject: Re: Regarding cables with lpt [NetBSD-0.9] [386BSD-0.1]
Message-ID: <1993Sep26.210525.12315@gmd.de>
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References: <284pa8$kio@sylvester.cc.utexas.edu>
Date: Sun, 26 Sep 1993 21:05:25 GMT
Lines: 69
In Message-ID: <284pa8$kio@sylvester.cc.utexas.edu> you write:
>In article <1993Sep26.163628.25349@gmd.de>,
>Holger Veit <veit@borneo.gmd.de> wrote:
>>The following is my cable.
>>male 25pin 36 pin Centronics (did you really have a 50 pin?
>> this could be a SCSI then? I doubt so)
>Oops, you are right, it was only a 36 pin. I got used to saying 50.
>
>>1-14 1-14
>>15 32
>>17 36
>>18-25 19-24 all tied together
>Really? All tied together? Are you sure that is right?
These lines are ground pins. Actually, a Centronics cable should have
seperately shielded wires for some lines, this one has one shield for
all, which is not strictly correct, but as long as it is not longer than
2 meters, it should be no problem.
>
>>
>>What is interesting is that pin 16 (D-Shell conn) is unconnected here.
>>This is (according to IBM tech ref manual) the "init" line
>>(from computer to printer) that sends a reset (low pulse 50 ms).
>Wait. You just said your cable was made to specs, and now you are saying
>it is not? I do not understand.
I repeated the HPLJ-4 manual on that which I consider to be a reference
to that. It is a matter of interpretation if the HP spec is is correct or not,
but it wasn't my idea to leave this unconnected, and it apparently has
no negative influence on the printer itself; it is resetted anyway on
power-on.
According to the manual: (this is translated from German):
.. you need:
..
* a high quality parallel cable with the correct wiring (see below [above]).
..
Configuration of the parallel cable
For best results, use a C2912B or equivalent cable. Most parallel cables
support Bi-Tronics communication, some of them, however, could have
an incompatible wiring. " (BTW: mine was "incompatible" before,
something like -fault tied to ground)
>
>>I actually opened my cable just now to verify this is true - it is!
>>And I remember, when I had problems (but reboot, not deselect)
>>that this line was connected; was solder at the pin.
>Are you suggesting that I should disconnect line 16? I do not understand
>what you mean.
I don't suggest anything, I am just reporting about the cable I use
with success. Actually this missing line 16 means that a cold reset
of the CPU does not mean a cold reset of the printer. I think resetting
the printer all the time is hardly necessary (except you use CTRL-ALT-DEL
to stop print spooling :-)) This brings up another question which is
speculative because I haven't looked at the lpt/lpa probing code yet:
does the driver create an init and then waits for some response, and
the timeout parameter for that is too low for some printers?
>--
>Protect our endangered bandwidth - reply by email. NO BIG SIGS!
>VaX#n8 vax@ccwf.cc.utexas.edu - Don't blame me if the finger daemon is down
--
Dr. Holger Veit | INTERNET: Holger.Veit@gmd.de
| | / GMD-SET German National Research | Phone: (+49) 2241 14 2448
|__| / Center for Computer Science | Fax: (+49) 2241 14 2342
| | / P.O. Box 13 16 | Had a nightmare yesterday:
| |/ Schloss Birlinghoven | My system started up with
53731 St. Augustin, Germany | ... Booting vmunix.el ...