Any path used for the transfer of data and control information between I/O adapters and storage controllers or storage devices. An I/O bus consists of cables, connectors, and all associated drivers, receivers, transducers, and other electronics required to make it function.

A host computer software component (usually part of an operating system) whose function is to control the operation of peripheral controllers or adapters attached to the host computer. I/O drivers communicate between distributor & reseller Applications and I/O devices, and in some cases may participate in data transfer, although this is rare with disk drivers, since most disk adapters and controllers contain hardware that performs data transfers.