help me driver

dear all,
please help me understand how can i start to write a driver for QNX?
how do i know that driver run true or wrong?

thanks anyway,

First, what kind of driver? Disk? Network? Serial I/O of some kind? USB? etc.

Most drivers run as a process, so you are allowed to put in printf statements, except for interrupt handlers. You can also use a debugger. A good place to start looking is in the documentation under resource managers, since many (but not all) drivers are resource managers.