HP-UX -How to find out the Processor Architecture( RISC or IA)

If you want to make out whether the HP-UX OS is running on PA(i.e. PA-RISC) or IA h/w without bothering about the specifics of the model of the processor, you can find that from the kernel itself :
file /stand/vmunix

e.g. :

bash-3.2# file /stand/vmunix

/stand/vmunix: ELF-64 executable object file - PA-RISC 2.0 (LP64)

Note:
Recent versions support the HP 9000 series of computer systems, based on the PA-RISC processor architecture, and HP Integrity systems, based on Intel's Itanium architecture