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From: metro@asi.UUCP.UUCP
Newsgroups: mod.computers.laser-printers
Subject: Re: PC to HP LJ line
Message-ID: <8703301811.AA16733@brillig.umd.edu>
Date: Fri, 27-Mar-87 22:04:02 EST
Article-I.D.: brillig.8703301811.AA16733
Posted: Fri Mar 27 22:04:02 1987
Date-Received: Tue, 31-Mar-87 07:32:58 EST
References: <8703270327.AA28535@ucbvax.Berkeley.EDU>
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: world
Organization: Assessment Systems, Inc., Philadelphia, PA
Lines: 28
Approved: laser-lovers@washington.arpa
Summary: I have see it with a diablo 630 printer.


In article <8703270327.AA28535@ucbvax.Berkeley.EDU>, UNM406@DBNRHRZ1.BITNET writes:
>   WE have a HP Laserjet, which is in the moment used simply as a
> printer for our IPM PC AT. (via the serial COM1-port). On the way from
> the PC to the printer we loose single bytes regularly (but without seeing
> a pattern in it).
>    Has anybody some idea what could happen, or has similar experience?
> 

I have seen the same thing with a Diablo 630 printer I was using.  The
problem turned out to be the following:

I was looping the CTS signal from the diablo back to its DTR signal to enable
it.  However, the printer used the CTS signal as a hardware handshaking line.
When the buffer got full it dropped the signal which inturn disabled its 
receiver -- thus clobbering the character which was currently being transmitted.

Only one character was lost, because the transmitting computer respected the
handshake, and did not transmit any more characters until the signal came
high again.

I hope the was you problem also.  The resolution was to use a different signal
to enable DTR -- preferably one from the transmitting computer.

-- 
Metro T. Sauper, Jr.                              Assessment Systems, Inc.
Director, Remote Systems Development              210 South Fourth Street
(215) 592-8900                 ..!asi!metro       Philadelphia, PA 19106