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 Secondly, inb()/outb() calls have been replaced by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