Abstract: A hardware-based system for managing multiple input/output devices sharing the same set of addresses in a computer system is described. The new VIRTUAL ENABLED state is a hybrid of the current ENABLED or ACTIVE and DISABLED or INACTIVE states. In the ENABLED state, an input/output (I/O) adapter responds to I/O addressing and presents interrupts to the processor. In the DISABLED state, the I/O adapter does not respond to I/O addressing and does not present interrupts. In the new VIRTUAL ENABLED state, the adapter does not respond to I/O addressing (as in the DISABLED state), but will still produce an interrupt (as in the ENABLED state). With the VIRTUAL state, multiple I/O adapters that would normally content for the same set of addresses (ENABLED state), or optionally be rendered inoperable (DISABLED state), can always remain available for I/O. A single register where the processor can read the interrupt status for all ENABLED and/or VIRTUAL ENABLED adapters sharing the same set of addresses is provided.