RM7965A-900UI 900 MHz 64-bit Microprocessor Data Sheet
6.3 Handshake Signals
There are 10 handshake signals on the system interface of the RM7965A. Two of these,
RdRdy* and WrRdy*, are common to all RM7965A CPUs. They are driven by an external
agent to indicate to the RM7965A whether it can accept a new read or write transaction. The
RM7965A samples these signals before deasserting the address on read and write requests.
ExtRqst* and Release* are also common to all RM7965A CPUs. They are used to transfer
control of the SysAD and SysCmd buses from the processor to an external agent. When an
external agent requires control of the bus, it asserts ExtRqst*. The RM7965A responds by
asserting Release* to release the system interface to slave state.
PRqst* and PAck* are supported by the RM7965A. These signals are used to transfer control
of the SysAD and SysCmd buses from the external agent to the processor. These two pins have
been added to the system interface to support multiple outstanding reads and facilitate non-
blocking cache operations. When the processor needs to reacquire control of the interface, it
asserts PRqst*. The external agent responds by asserting PAck* to return control of the
interface to the processor.
RspSwap* is used by the external agent to indicate to the processor when it is returning
multiple data requests out of order. For example, when there are two outstanding reads, the
external agent asserts RspSwap* when it is going to return the data for the second read before it
returns the data for the first read.
RdType is a pin on the interface that indicates whether a read is an instruction read or a data
read. When asserted, the reference is an instruction read. When deasserted it is a data read.
RdType is only valid during valid address cycles.
ValidOut* and ValidIn* are used by the RM7965A and its external agents to indicate that there
is a valid command and data on the SysAD and SysCmd buses. The RM7965A asserts
ValidOut* when it is driving these buses with a valid command and data, and the external agent
drives ValidIn* when it has control of the system interface and is driving a valid command and
data.
Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC-2100294, Issue 2
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