a system for providing notification , to the associated operating system , of removal and replacement of i / o devices during operation of a multiprocessor computer system running multiple operating systems . the system includes a plurality of cells , each containing multiple risc processors , low - level i / o firmware , a local service processor , scratch ram , external registers , a memory and i / o manager , and interfacing hardware . each partition comprises one or more cells and runs its own operating system . each cell is connected to a peripheral backplane containing a plurality of peripheral i / o card slots via a switch on the system backplane , which also connects the cell to a supervisory processor , which sends card slot status information to the appropriate cell . each i / o card slot has an associated latch which provides an indication , to the supervisory processor , that a platform event has occurred . platform events include inserting or removing an i / o card to / from a card slot , and opening an access panel that provides access to the i / o cards .