99 lines
3.3 KiB
Groff
99 lines
3.3 KiB
Groff
.\"
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.\" Copyright (c) 1993 Christopher G. Demetriou
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.\" Copyright (c) 1994 Geoffrey M. Rehmet
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.\" Copyright (c) 1999 Nicolas Souchu
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd February 14, 1999
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.Dt LPT 4
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.Os
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.Sh NAME
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.Nm lpt
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.Nd generic printer device driver
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.Sh SYNOPSIS
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.Cd "device ppc"
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.Cd "device ppbus"
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.Cd "device lpt"
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.Sh DESCRIPTION
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The current
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.Em lpt
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driver is the port of the original lpt driver to the
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.Xr ppbus 4
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system.
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.Pp
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One purpose of this port was to allow parallel port sharing with other
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parallel devices.
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Secondly, inb()/outb() calls have been replaced by ppbus
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function calls.
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lpt is now arch-independent thanks to the ppbus interface.
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See
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.Xr ppbus 4
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for more info about the ppbus system.
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.Pp
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The parallel port bus is allocated by lpt when the printer device is opened
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and released only when the transfer is completed: either when the device
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is closed or when the entire buffer is sent in interrupt driven mode.
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.Pp
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The driver can be configured to be either interrupt-driven, or
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to poll the printer.
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Ports that are configured to be
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interrupt-driven can be switched to polled mode by using the
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.Xr lptcontrol 8
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command.
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.Pp
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Depending on your hardware, extended capabilities may be configured with the
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.Xr lptcontrol 8
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command.
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With an ECP/ISA port, you can take advantage
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of FIFO and DMA.
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.Pp
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In order to retrieve printer info from /dev/lpt0, just apply the
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.Nm cat
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command to the device.
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If the printer supports IEEE1284 nibble mode and has
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data to send to the host, you will get it.
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.Sh FILES
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.Bl -tag -width Pa -compact
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.It Pa /dev/lpt0
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first parallel port driver
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.El
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.Sh SEE ALSO
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.Xr ppbus 4 ,
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.Xr ppc 4 ,
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.Xr lptcontrol 8
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.Sh HISTORY
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This driver replaces the functionality of the lpa
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driver, which is now defunct.
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.Sh BUGS
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There are lots of them, especially in cheap parallel port implementations.
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.Pp
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It is only possible to open a lpt port when a printer is connected and
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on-line, making it impossible to run
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.Xr lptcontrol 8
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when there is no printer connected.
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.Pp
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This driver could still stand a rewrite.
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