Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!hplabs!hpfcso!hpfcdc!perry
From: perry@hpfcdc.HP.COM (Perry Scott)
Newsgroups: comp.sys.hp
Subject: Re: Serial LaserJet printing!
Message-ID: <5570541@hpfcdc.HP.COM>
Date: 28 Nov 90 23:06:16 GMT
References: <1990Nov27.111210@dali.gatech.edu>
Organization: HP Fort Collins, Co.
Lines: 24

>mike@penguin.gatech.edu (Mike Gourlay)
>Hi,
>
>	I connected an HP laserJet Series II to my HPUX 370 serial port
>using a cable I built to go from the 370's 9 pin RS-232 to the printer's 25 pin
>RS-232.  I created the printer, and when I send stuff to it using lp, the 
>header page gets printed, and part of the first page of the printout, and then
>the printer drops DTR, give ERROR 22 (protocol error), and the HPUX 370 keeps
>sending data over the serial line, even though the printer doesn't want it.
>
>	Mike

The LaserJet II drops DTR to tell the computer to stop sending.  Apparently,
this is The Right Thing To Do if you are a PC, the LJ-II's primary market.

The solution is to kludge up a cable that connects DTR on the printer end
to CTS on the computer end.  HP makes such an animal, but I don't know
what it is.  Then, enable CTS pacing by ORing 0x08 into the minor number
of the tty file.  I think this incantation should work:

mknod /dev/tty09 c 1 0x09000C

Perry Scott
Ex-300-tty-guru