Channel Processor With Microcode Routines to Run As a Unit Exerciser and to Handle Sense Data From a Unit Directly Without the Processing Normally Performed by Operating System
Original Publication Date: 1989-Oct-01
Included in the Prior Art Database: 2005-Jan-29
When certain faults have occurred in a conventional data transfer between a channel processor and an I/O unit, the "unit check" bit is set in the status byte which the I/O unit sends to the channel as part of the ending sequence of a data transfer. Additional information about the fault is transferred from the unit when the channel executes a Sense CCW (Channel Command Word).