Channel state bits.

摘要

An I/O channel is described which contains multiple clocking partitions and is controlled by the main system processor over an I/O bus that is common with other I/O channels, thus decoupling the channel from continuous processor monitoring. A dual set of state bits convey to the main processor over an asynchronous boundary the state of the channel interface and the link. The origin of the channel interface state bit is a function of whether the main processor is issuing a new command. Link state bits are real time or latched as a function of channel state. Link state values have been assigned using Gray code for assuring accurate determination of link state at the instant of failure, to avoid false readings at state transitions due to asynchronous internal channel clocking.