Path: utzoo!attcan!uunet!munnari.oz.au!metro!bunyip!brolga!exnirad
From: exnirad@brolga.cc.uq.oz (Nirad Sharma)
Newsgroups: comp.terminals
Subject: Re: Transparent printing through ANSI teminal local printer
Keywords: transparent, ANSI, local, printer
Message-ID: <2331@bunyip.cc.uq.oz>
Date: 20 Mar 90 04:04:08 GMT
References: <2329@bunyip.cc.uq.oz>
Sender: news@bunyip.cc.uq.oz
Distribution: comp
Lines: 46

I am posting the answer to my original question :

>Does anyone out there know what the codes are to start and stop transparent
>printing through an ANSI terminal's local attached printer ? Note that this is
>slightly different from just echoing output to the local printer. Transparent
>printing in the context I am using refers to the use of the local printer by
>other terminals while the printer's terminal is being used by its owner.

  As I had already discovered, 'esc [ ? 5 i' starts ECHOING terminal output to
the locally-attached printer while 'esc [ ? 4 i' stops echoing terminal output.
The codes to turn on and off, respectively, transparent printing are
'esc [ 5 i' and 'esc [ 4 i' (no question mark). (This was provided by Tim
Peiffer <peiffer@cs.umn.edu>.)

  I have been told that implementation of transparent printing poses problems,
more specifically . . .

>Date: Tue, 20 Mar 90 09:31:51 NZT
>From: Jim Shaw <jim@unisys.co.nz>
>Organization: Unisys New Zealand

>Transparent print requires special driver support to enable multiple processes
>to share one serial line ( tty & printer). . .
>Typically a driver is written to use a different minor number for
>communicating with the printer. A special ioctl call tells the driver what the
>escape sequence to enable/disable tranparent print is. The driver then has to
>synchronise physical writes to the port so that printer and terminal get the
>correct data.

>I am looking at implementing a driver to do this and would be interested in
>keeping in touch if you have any thoughts, problems etc. The major stumbling
>block is getting source/specs for the hardware level interface.

  I can't provide any help here but maybe someone else can help. I have
my terminals connected to an Anvil board providing APS, "Attached Printer
Support", which creates a separate prn device e.g. /dev/prn005 for /dev/tty005,
which the OS treats as any other printer device. The Anvil board does all the
work - it works like a charm.

  Thanks again for all the responses.


Nirad Sharma  (exnirad@brolga.cc.uq.oz.au)
Continuing Education Unit,
The University of Queensland,
AUSTRALIA