4.7. Run Time Access to Plug and Play registers

Read access to Plug and Play configuration is available at all times with no impact to the function(s) on the card. However, write accesses to Plug and Play registers must be done with the full knowledge of the device driver controlling the device and the operating system environment. Even though it is possible to re-assign the CSNs during run time, this is not necessary since CSNs for all Plug and Play cards are assigned during initialization. The only exception to this case is for docking stations, hot-insertion capability or if power management is supported. It is required that prior to changing the value of any registers, the logical device be de-activated, the resource register re-programmed, and the logical device is activated again. When finished accessing Plug and Play registers, all cards must be returned to the Wait for Key state.