If the port configuration is correct and you still
cannot redirect output to the port,
try using a different device name.
For example, for a parallel port,
use lp1 instead of lp0.
For a serial port, use tty2a instead of tty1a.
Pay attention to the unit= message for parallel ports
on the boot screen or use hwconfig
(for example, unit=0 corresponds to lp0).
If you still cannot print using a different device name,
your printer may be defective; check the printer documentation.
If you cannot print from DOS, check the printer hardware configuration.
See the documentation provided with your printer.
If you configured your printer correctly
and you still cannot redirect output to it,
the problem is most likely a hardware malfunction.
Recheck the cables and port configuration and
consult your hardware documentation.