At this point, the BIOS or operating system will program the memory-mapped and I/O port addresses into the device's BAR configuration register. These addresses stay valid as long as the system remains turned on. Upon power-off, all these settings are lost and the procedure is repeated next time the system is powered back on. Since this entire process is fully automated, the user is spared the task of configuring any newly added hardware manually by changing DIP switches on the cards themselves. This automatic device discovery and address space assignment is how plug and play is implemented.