12.3 System Interface Protocols

External Arbitration

The System interface must be in slave state for the external agent to issue an external request through the System interface. The transition from master state to slave state is arbitrated by the processor using the System interface handshake signals ExtRqst* and Release*. This transition is described by the following procedure:

1. An external agent signals that it wishes to issue an external request by asserting ExtRqst*.

2. When the processor is ready to accept an external request, it releases the System interface from master to slave state by asserting Release* for one cycle.

3. The System interface returns to master state as soon as the issue of the external request is complete.

This process is described in External Arbitration Protocol, later in this chapter.

Copyright 1996, MIPS Technologies, Inc. -- 21 MAR 96

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