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NAME    [Toc]    [Back]

       lp - line printer devices

SYNOPSIS    [Toc]    [Back]

       #include <linux/lp.h>

CONFIGURATION    [Toc]    [Back]

       lp[0-2] are character devices for the parallel line printers; they have
       major number 6 and minor number 0-2.  The minor numbers	correspond  to
       the  printer  port  base  addresses 0x03bc, 0x0378 and 0x0278.  Usually
       they have mode 220 and are owned by root and group  lp.	 You  can  use
       printer	ports  either with polling or with interrupts.	Interrupts are
       recommended when high traffic is expected,  e.g.  for  laser  printers.
       For  usual  dot	matrix	printers  polling will usually be enough.  The
       default is polling.

DESCRIPTION    [Toc]    [Back]

       The following ioctl(2) calls are supported:

       int ioctl(int fd, LPTIME, int arg)
	      Sets the amount of time that the driver sleeps before rechecking
	      the  printer  when  the printer's buffer appears to be filled to
	      arg.  If you have a fast printer, decrease this number;  if  you
	      have  a slow printer then increase it.  This is in hundredths of
	      a second, the default 2 being 0.02 seconds.  It only  influences
	      the polling driver.

       int ioctl(int fd, LPCHAR, int arg)
	      Sets  the  maximum  number  of  busy-wait  iterations  which the
	      polling driver does while waiting for the printer to  get  ready
	      for  receiving  a  character  to	arg.  If printing is too slow,
	      increase this number; if the system gets too slow, decrease this
	      number.	The  default  is 1000.	It only influences the polling

       int ioctl(int fd, LPABORT, int arg)
	      If arg is 0, the printer driver will retry on errors,  otherwise
	      it will abort.  The default is 0.

       int ioctl(int fd, LPABORTOPEN, int arg)
	      If  arg  is 0, open(2) will be aborted on error, otherwise error
	      will be ignored.	The default is to ignore it.

       int ioctl(int fd, LPCAREFUL, int arg)
	      If arg is 0, then the out-of-paper, offline  and	error  signals
	      are  required  to  be  false  on	all writes, otherwise they are
	      ignored.	The default is to ignore them.

       int ioctl(int fd, LPWAIT, int arg)
	      Sets the number of busy waiting iterations to wait before strobing
 the printer to accept a just-written character, and the number
 of iterations to wait before turning the strobe  off	again,
	      to  arg.	 The  specification  says  this  time  should  be  0.5
	      microseconds, but experience has shown the delay caused  by  the
	      code  is	already enough.  For that reason, the default value is
	      0.  This is used for both the polling and the interrupt  driver.

       int ioctl(int fd, LPSETIRQ, int arg)
	      This  ioctl()  requires  superuser  privileges.  It takes an int
	      containing the new IRQ as  argument.   As  a  side  effect,  the
	      printer  will  be reset.	When arg is 0, the polling driver will
	      be used, which is also default.

       int ioctl(int fd, LPGETIRQ, int *arg)
	      Stores the currently used IRQ in arg.

       int ioctl(int fd, LPGETSTATUS, int *arg)
	      Stores the value of the status port in arg.  The bits  have  the
	      following meaning:

	      LP_PBUSY	   inverted busy input, active high
	      LP_PACK	   unchanged acknowledge input, active low
	      LP_POUTPA    unchanged out-of-paper input, active high
	      LP_PSELECD   unchanged selected input, active high
	      LP_PERRORP   unchanged error input, active low

	      Refer  to  your  printer	manual for the meaning of the signals.
	      Note that undocumented bits may also be set, depending  on  your

       int ioctl(int fd, LPRESET)
	      Resets the printer.  No argument is used.

FILES    [Toc]    [Back]


AUTHORS    [Toc]    [Back]

       The printer driver was originally written by Jim Weigand and Linus Torvalds.
  It was further improved by Michael K. Johnson.	The  interrupt
       code was written by Nigel Gamble.  Alan Cox modularised it.  LPCAREFUL,
       LPABORT, LPGETSTATUS were added by Chris Metcalf.

SEE ALSO    [Toc]    [Back]

       mknod(1), chown(1), chmod(1), tunelp(8), lpcntl(8)

				  1995-01-15				 LP(4)
[ Back ]
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