xref: /freebsd/share/man/man4/lpt.4 (revision 640235e2c2ba32947f7c59d168437ffa1280f1e6)
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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49Secondly, inb()/outb() calls have been replaced by ppbus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.
62Ports that are configured to be
63interrupt-driven can be switched to polled mode by using the
64.Xr lptcontrol 8
65command.
66.Pp
67Depending on your hardware, extended capabilities may be configured with the
68.Xr lptcontrol 8
69command.
70With an ECP/ISA port, you can take advantage
71of FIFO and DMA.
72.Pp
73In order to retrieve printer info from /dev/lpt0, just apply the
74.Nm cat
75command to the device.
76If the printer supports IEEE1284 nibble mode and has
77data to send to the host, you will get it.
78.Sh FILES
79.Bl -tag -width Pa -compact
80.It Pa /dev/lpt0
81first parallel port driver
82.El
83.Sh SEE ALSO
84.Xr ppbus 4 ,
85.Xr ppc 4 ,
86.Xr lptcontrol 8
87.Sh HISTORY
88This driver replaces the functionality of the lpa
89driver, which is now defunct.
90.Sh BUGS
91There are lots of them, especially in cheap parallel port implementations.
92.Pp
93It is only possible to open a lpt port when a printer is connected and
94on-line, making it impossible to run
95.Xr lptcontrol 8
96when there is no printer connected.
97.Pp
98This driver could still stand a rewrite.
99