*BSD News Article 21415


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From: veit@borneo.gmd.de (Holger Veit)
Subject: Re: Regarding cables with lpt [NetBSD-0.9] [386BSD-0.1]
Message-ID: <1993Sep26.163628.25349@gmd.de>
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Organization: GMD - German National Research Center for Computer Science
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References: <283plm$igg@sylvester.cc.utexas.edu>
Date: Sun, 26 Sep 1993 16:36:28 GMT
Lines: 46

>Here is the result of the continuity test for the lpt cable:
>Male 25-pin Dshell			Female Centronics 50 "pin"
>1-14						1-14
>15						32
>16						31
>17						36
>18						33
>19,20,21,22,23,24				19,21,23,25,27,29
>25						30
>
>Symptoms:  printer not recognized on bootup under 386BSD-0.1 pk0.2.3
>or NetBSD-0.9... printer IS recognized if a printer switch is used to
>detach it during bootup.  Printer is a HP-LJ2, not a bottom-of-the-barrel
>line printer.

>VaX#n8 vax@ccwf.cc.utexas.edu - Don't blame me if the finger daemon is down

Well, since I am notorious for "check your cable first" responses, the 
following is my cable. I made this exactly after the description in my
HP-LJ-4L manual (apx. A-2). This is a "bi-tronics" interface cable
(i.e. the LJ4L printer can send responses back to the computer), but I
doubt this should be a problem with a printer that doesn't.
It differs in details to your setting.

male 25pin	36 pin Centronics (did you really have a 50 pin?
				   this could be a SCSI then? I doubt so)
1-14		1-14
15		32
17		36
18-25		19-24 all tied together

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).
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.
Hope this helps.

--
         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 ...