MeeWee

Thanks for the answers. I am thinking for a scenario like this: I have a USB i plug it in my computer that is unable to boot from the usb, i get a message that is asking me if i want to start the OS and if i accept, the base OS is cleared from memory and meantime the new OS loads from the USB into memory. Is it possible?

I'm asking if anyone knows or can give me details about how i can switch from one OS to another without havind to restart the computer just push the next kernel into memory and run it. thanks ,