Motorola MVME2400 Series Programmer's Reference Manual page 87

Arbitration
The PCI Master can support parking on the PCI bus. There are two cases
where the PCI Master continuously asserts its request.
If the PCI Master starts a transaction that is going to take more than
one assertion of FRAME_, the PCI Master continuously asserts its
request until the transaction has completed. For example, the PCI
Master continuously asserts requests during the first part of a two
part critical word first transaction.
If at least one command is pending within the PPC FIFO.
The PCI Master always removes its request when it receives a disconnect
or a retry.
There is a case where the PCI Master could assert a request but not actually
perform a bus cycle. This may happen if the PCI Master is placed in the
speculative request mode. Refer to the section entitled
Contention Handling
assert its request for more than 16 clocks without starting a transaction.
Fast Back-to-Back Transactions
The PCI Master does not generate fast back-to-back transactions.
Arbitration Latency
Because a bulk of the transactions are limited to single-beat transfers on
PCI, the PCI Master does not implement a Master Latency Timer.
Exclusive Access
The PCI Master is not able to initiate exclusive access transactions.
Address/Data Stepping
The PCI Master does not participate in the Address/Data Stepping
protocol.
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Functional Description
PCI/PPC
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