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 Secondly, inb()/outb() calls have been replaced by ppbus function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