HP 3000 Manuals

System Startup, Configuration, and Shutdown Reference Manual

I/O Paths 

An I/O path is the system address assigned to the device interface
hardware and the physical path used to reach an I/O device.  Additions,
changes, or deletions to an I/O path require that the path identify the
applicable device adapter interfaces and their associated I/O devices. 

At system power on or reset, the processor-dependent code (PDC) and
I/O-dependent code (IODC) hardware routines read and initialize the I/O
paths used to boot or reboot the system.  The I/O paths that are used to
load the system from disk or tape are referred to as boot paths.

MPE/iX 5.0 Documentation