CD1865 Datasheet, PDF (45/150 Pages) Intel Corporation – Intelligent Eight-Channel Communications Controller

Intelligent Eight-Channel Communications Controller — CD1865
devices. In multiple-device systems, either disable daisy chaining on all devices and ‘fish’ each
individually, or disable daisy chaining on the last device only and ‘fish’ the device at the beginning
of the chain.
Both methods of acknowledging service requests can be used interchangeably. It is usually
advantageous to use Mixed mode. For example, after receiving an interrupt and servicing it in the
normal manner, the host should read the Service Request Status register (SRSR) to see if other
requests are pending. If so, the host can acknowledge by reading the appropriate Request
Acknowledge register (RRAR, TRAR, and MRAR) and proceed to service the request. This avoids
the time required for the host to exit its interrupt routine, only to re-enter it immediately for the next
request.
Datasheet
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