Fast parallel driver for Unix/Xenix AT?

Brad Templeton brad at
Fri Dec 1 18:00:09 AEST 1989

On SCO Unix 3.2, the parallel performance was dreadful to my laserjet.

The reason is the IPL level.  The kernel is compiled with serial ports at
an IPL level of 7 (the highest) and the printer at level 2 or 3, I think.

Raise the IPL level to 5, and you can print quickly.

Of course, SCO 3.2.0 has an annoying bug of not being able to handle
bytes with the MSB turned on, so you have to write a filter, and that's
a pain, so going to 19.2k serial may be the way to go anyway, particularly
if you have a smart serial card.
Brad Templeton, ClariNet Communications Corp. -- Waterloo, Ontario 519/884-7473

More information about the Comp.unix.i386 mailing list