6.9 System Interface Requests and Responses

Outstanding Requests and Request Numbers

The processor allows requests and corresponding responses to be split transactions, which enables additional processor and external requests to be issued while waiting for a prior response. The System interface supports a request number field to link requests with their corresponding responses, so responses can be returned out of order.

The processor allows a maximum of eight outstanding requests on the System interface through a 3-bit request number. These outstanding requests may be composed of any mix of processor and external requests.

An individual processor (as opposed to the System interface, above) supports a maximum of four outstanding processor requests at any given time.

Copyright 1996, 1997, MIPS Technologies, Inc. -- 09 DEC 96

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