xref: /freebsd/share/man/man4/lpt.4 (revision a220d00e74dd245b4fca59c5eca0c53963686325)
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2.\" Copyright (c) 1993 Christopher G. Demetriou
3.\" Copyright (c) 1994 Geoffrey M. Rehmet
4.\" Copyright (c) 1999 Nicolas Souchu
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28.\" $FreeBSD$
29.\"
30.Dd February 14, 1999
31.Dt LPT 4
32.Os
33.Sh NAME
34.Nm lpt
35.Nd generic printer device driver
36.Sh SYNOPSIS
37.Cd "device ppc"
38.Cd "device ppbus"
39.Cd "device lpt"
40.Sh DESCRIPTION
41The current
42.Em lpt
43driver is the port of the original lpt driver to the
44.Xr ppbus 4
45system.
46.Pp
47One purpose of this port was to allow parallel port sharing with other
48parallel devices.
49Secondly, inb()/outb() calls have been replaced by ppbus
50function calls.
51lpt is now arch-independent thanks to the ppbus interface.
52See
53.Xr ppbus 4
54for more info about the ppbus system.
55.Pp
56The parallel port bus is allocated by lpt when the printer device is opened
57and released only when the transfer is completed: either when the device
58is closed or when the entire buffer is sent in interrupt driven mode.
59.Pp
60The driver can be configured to be either interrupt-driven, or
61to poll the printer.  Ports that are configured to be
62interrupt-driven can be switched to polled mode by using the
63.Xr lptcontrol 8
64command.
65.Pp
66Depending on your hardware, extended capabilities may be configured with the
67.Xr lptcontrol 8
68command.
69With an ECP/ISA port, you can take advantage
70of FIFO and DMA.
71.Pp
72In order to retrieve printer info from /dev/lpt0, just apply the
73.Nm cat
74command to the device.
75If the printer supports IEEE1284 nibble mode and has
76data to send to the host, you'll get it.
77.Sh SEE ALSO
78.Xr ppbus 4 ,
79.Xr ppc 4 ,
80.Xr lptcontrol 8
81.Sh HISTORY
82This driver replaces the functionality of the lpa
83driver, which is now defunct.
84.Sh FILES
85.Bl -tag -width Pa -compact
86.It Pa /dev/lpt0
87first parallel port driver
88.El
89.Sh BUGS
90There are lots of them, especially in cheap parallel port implementations.
91.Pp
92It is only possible to open a lpt port when a printer is connected and
93on-line, making it impossible to run
94.Xr lptcontrol 8
95when there is no printer connected.
96.Pp
97This driver could still stand a rewrite.
98