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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  Secondly, inb()/outb() calls have been replaced by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.