lpt(7)                           DG/UX R4.11                          lpt(7)


NAME
       lpt - Parallel line printer controller (Intel only)

SYNOPSIS
       lpt(0,controller-num)

DESCRIPTION
       To configure an lpt device, you must add a device name entry to the
       DG/UX system configuration file of the form described in the synopsis
       above.  The parameters in a device name have the following meanings:

       ·   The controller-num parameter is a number which distinguishes the
           various instances of the controller that are available.  The
           controller-num is one based and may range from 1 to 3 dependent
           on the jumpering of your parallel port device.

       The printer driver takes the characters written to it and sends them
       to the line printer hardware. If the printer hardware takes special
       action in response to particular characters output to the device,
       such as form feeds, the application may take advantage of these
       features by outputting the appropriate characters, but there are no
       dependencies on these features within the driver. The driver does not
       perform any special paper spacing or other forms control to handle
       paper folds, etc.

       A printer is an exclusive open device. The error ENXIO is returned if
       an attempt is made to open a printer that has already been opened.

       For the close system call, user visible functionality is the same as
       for an ordinary disk file.  The only exception is that the device
       will pend until all data has been written or flushed from the device
       if the device is in a blocking state (see open(1) and fcntl(1)).
       This means that the close may pause while waiting for Out of Paper,
       Not Selected, etc... errors to be resolved.  The close may be forced
       in these conditions with a signal.

       The read system call is not supported.  The error ENODEV is always
       returned.

       For the write system call, the contents of the caller's buffer are
       sent to the physical line printer.  If an error occurs on the I/O,
       the error EIO is returned.  If the printer is off-line when a write
       is started, or goes off-line while a write is in progress, the system
       call will pend until the printer is on-line and the data is written.

       Select always returns READY for both read and write operations.

FILES
       The lpt device creates a single character-special device node per
       controller when it is configured, with the pathname:

           /dev/parallel/lpt(0,controller-num)


SEE ALSO
       lp(1).


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