HP-UX

The serial number is stored in stable storage. That the same place that the boot path, autoboot flag, fastboot setting, etc are stored. It just a eeprom chip.

Thanks perderabo,
Thats what I believed before reading this thread, then I was starting to have serious doubts for I didnt see any reason it would have been affected by reinstall of OS for selling...
Youve made my day...
I went through old notes and found a comment of Bill Hassell :
The majority of HP 9000 computers do not have the serial number stored electronically.
Only the more recent machines such as the rp series and earlier models like N and L
class have this number.."

And wondered about workstation so I just tried:

Code:

System Hardware

    Model:              9000/785/B2600
    Main Memory:        3072 MB
    Graphics:           HP VISUALIZE-FXE color 1280x1024 48 planes
    Processors:         1
    OS mode:            64 bit
    LAN hardware ID:    0x00306E2B2C1C
    LAN hardware ID:    0x00306E370832
    Software ID:        2012698290
    Keyboard Language:  USB_PS2_DIN_US_English
...
.
.
dm2 # echo "sel path system\ninfolog\nexit"|cstm|grep "System Serial Number"
dm2 #

Dont forget, if you are cloning a system and dont try a fresh install, you will not be able to get the serial number of an hp-ux risc system.