lpt(3) [plan9 man page]

LPT(3)							     Library Functions Manual							    LPT(3)

NAME

       lpt - parallel port interface for PC's

SYNOPSIS

       bind -a #L[123] /dev

       /dev/lpt[123]data
       /dev/lpt[123]dlr
       /dev/lpt[123]pcr
       /dev/lpt[123]psr

DESCRIPTION

       The  lpt  driver  provides an interface to the parallel interface normally used for printers.  The specifiers 1, 2, and 3 correspond to the
       parallel interfaces at PC ports 0x3bc, 0x378, and 0x278 respectively.

       Lpt?data is write only.	Writing to it sends data to the interface.  This file is sufficient for communicating with most printers.

       Lpt?dlr, lpt?pcr, and lpt?psr are used for fine control of the parallel port.  Reading or writing these files corresponds  to  reading  and
       writing	the  data  latch  register,  printer  control  register, and printer status register.  These are used by programs to drive special
       devices.

SOURCE

       /sys/src/9/pc/devlpt.c

																	    LPT(3)

LPT(4)							   BSD Kernel Interfaces Manual 						    LPT(4)

NAME

     lpt -- generic printer device driver

SYNOPSIS

     device ppc
     device ppbus
     device lpt

DESCRIPTION

     The current lpt driver is the port of the original lpt driver to the ppbus(4) system.

     One purpose of this port was to allow parallel port sharing with other parallel devices.  Secondly, inb()/outb() calls have been replaced by
     ppbus function calls.  lpt is now arch-independent thanks to the ppbus interface.	See ppbus(4) for more info about the ppbus system.

     The parallel port bus is allocated by lpt when the printer device is opened and released only when the transfer is completed: either when the
     device is closed or when the entire buffer is sent in interrupt driven mode.

     The driver can be configured to be either interrupt-driven, or to poll the printer.  Ports that are configured to be interrupt-driven can be
     switched to polled mode by using the lptcontrol(8) command.

     Depending on your hardware, extended capabilities may be configured with the lptcontrol(8) command.  With an ECP/ISA port, you can take
     advantage of FIFO and DMA.

     In order to retrieve printer info from /dev/lpt0, just apply the cat command to the device.  If the printer supports IEEE1284 nibble mode and
     has data to send to the host, you will get it.

FILES

     /dev/lpt0			       first parallel port driver

SEE ALSO

     ppbus(4), ppc(4), lptcontrol(8)

HISTORY

     This driver replaces the functionality of the lpa driver, which is now defunct.

BUGS

     There are lots of them, especially in cheap parallel port implementations.

     It is only possible to open a lpt port when a printer is connected and on-line, making it impossible to run lptcontrol(8) when there is no
     printer connected.

     This driver could still stand a rewrite.

BSD
								 February 14, 1999							       BSD