Concurrent Maintenance Functions for the Channel Adapters in a Communication Controller
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-27
In a communication controller such as shown in the drawing, several types of adapters are connected to a central control unit (CCU) through an input/output (I/O) bus to insure the exchange of information between devices connected to the line adapters (LAs) and host systems (not shown) through channel adapters (CAs). The channel adapters are interconnected in daisy chain configurations for selection purposes. This article describes how the channel adapters may be disconnected from the daisy chains while the communication controller continues to operate. The channel adapters are not only connected to the I/O bus but are also connected together in a daisy chain arrangement for two reasons: cycle steal and auto-selection.