Logical Control Unit
Original Publication Date: 1982-Oct-01
Included in the Prior Art Database: 2005-Feb-10
A "logical control unit" (LCU), as presently contemplated is a collection of stored information and associated firmware or the equivalent for enabling an I/O channel processing subsystem of a data processing system to control the initiation of I/O activities and to select specific channel interfaces and control units for such activities. Each LCU is associated with a unique maximal set of (physical) control unit elements which offer alternative paths of access to (physical) device elements. For example, if a device A is accessible through control units 1 and 2, a device B through control units 2 and 3, and a device C through control units 3 and 4- and if control units 1-4 do not offer alternative paths of device access relative to any other control units- then control units 1-4 constitute a set associated uniquely with an LCU.