Return to lp CVS log

Up to [MW Coherent from dump] / coherent / a / usr / man / COHERENT

coherent

lp                        Device Driver                        lp




Line printer driver


Files /dev/lp*  access the line-printer's device  drivers for IBM
AT COHERENT.  The drivers are assigned major device number 3.

The COHERENT  system supports three printers,  in both cooked and
raw modes.   The following gives  the device name,  minor device,
and I/O port:


     /ddeevv/llpptt11 0  0x3BC  (/etc/mknod /dev/lpt1  c 3   0)
     /ddeevv/llpptt22 1  0x378  (/etc/mknod /dev/lpt2  c 3   1)
     /ddeevv/llpptt33 2  0x278  (/etc/mknod /dev/lpt3  c 3   2)
     /ddeevv/rrllpptt11128  0x3BC  (/etc/mknod /dev/rlpt1 c 3 128)
     /ddeevv/rrllpptt22129  0x378  (/etc/mknod /dev/rlpt2 c 3 129)
     /ddeevv/rrllpptt33130  0x278  (/etc/mknod /dev/rlpt3 c 3 130)


``Cooked'' processing processes  the special characters BS (back-
space), HT (horizontal tab),  LF (line feed), FF (form feed), and
CR (carriage return)  appropriately; raw processing simply passes
them on to the printer.

The driver uses  a hybrid busy-wait/timeout discipline to support
printers efficiently  that have varying buffer  sizes in a multi-
tasking environment.

The kernel variable LPWAIT  is the time during that the processor
waits  for the  printer  to accept  the next  character.  If  the
printer  is not  ready within  the LPWAIT  time period,  the then
processor resumes  normal processing for the  number of ticks set
by  LPTIME Thus,  setting LPWAIT  to a  very large  number (e.g.,
30,000) and LPTIME to a  very small number (e.g., one) results in
a fast printer,  but slow processing on other tasks.  Conversely,
setting LPWAIT to a small number (e.g., 50) and LPTIME to a large
number (e.g.,  five) result in efficient  multi-tasking, but also
results in  a slow printer  unless the printer  itself contains a
buffer (as  is presently normal with all  except the least expen-
sive printers).   By default, LPWAIT is set to  100 and LPTIME to
four.  We recommend  that you set LPWAIT to no  less than 50, and
LPTIME to no less than one.

***** Files *****

/ddeevv/llpp* -- ``Cooked'' printer interfaces
/ddeevv/rrllpp* -- Raw printer interfaces

***** See Also *****

ascii, device drivers, epson, lpr





COHERENT Lexicon                                           Page 1

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.