Explain System bus arbitration in Loosely Coupled System

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written 7.7 years ago by

teamques10 ★ 64k

A loosely coupled configuration provides the following advantages:
High system throughput can be achieved by having more than one CPU.
The system can be expanded in a modular form. Each bus master module is an independent unit and normally resides on a separate PC board. Therefore, a bus master module can be added or removed without affecting the other modules in the system.
A failure in one module normally does not cause a breakdown of the entire system and the faulty module can be easily detected and replaced.
Each bus master may have a local bus to access dedicated memory or I/O devices so that a greater degree of parallel processing can be achieved.
More than one bus master module may have access to the shared system bus- extra bus control logic must be provided to resolve the bus arbitration problem.
The extra logic is called bus access logic and it is its responsibility to make sure that only one bus master at a time has control of the bus.
Simultaneous bus requests are resolved on a priority basis.
There are three schemes for establishing priority:
Daisy chaining.
Polling.
Independent requesting.

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