CPC700 User’s Manual—Preliminary
3-7
3.6.1 CPC700 Response for Processor to System Memory
Accesses
The following table corresponds to the state of the processor address bus for a given cycle (which may or
may not be pipelined) and the corresponding response from CPC700. NOTE: For any of the transactions
listed, the internal memory controller interface may be idle or busy (servicing a processor to memory write
buffer flush or finishing the data tenure of a previous PCI or processor access to system memory). If the
internal memory controller interface (MCIF) is busy, the address for the processor to memory access is
placed on the MCIF as soon as possible. The data tenure for the requested access will execute on the
MCIF following the completion of the in progress data tenure.
Once the processor request is accepted, as indicated by the assertion of AACK_N to the processor, data
will be transferred at the earliest available opportunity.
Note: In Table 8., the state of the processor to PLB write buffer is a “don’t care.”
Table 9. lists the corresponding memory controller interface requests generated in response to processor
requests to/from system memory.
Table 8. CPC700 Response for processor to System Memory Transactions
Proc
Proc-Mem
W.B.
Response
Mem Rd
Deallocated
AACK_N CPU and return data from system memory
Mem Rd
Allocated,
Miss
Bypass processor-Mem W.B., AACK_N CPU and return data from system mem-
ory
Mem Rd
Allocated,
Hit
ARTRY_N CPU, High Priority write for processor-Mem W.B. flush
Mem Wr
Deallocated
Post write in
processor
-Mem W.B.
Mem Wr
Allocated,
Miss
ARTRY_N CPU, High Priority write for processor-Mem W.B. flush
Mem Wr
Allocated,
Hit
ARTRY_N CPU, High Priority write for processor-Mem W.B. flush
Table 9. Processor to Memory Cycle Translation
Processor to MEM Transfer (Rd or Wr)
Memory Controller I/F Request
Single Beat
Doubleword with byte enables
Burst(32 byte)
Quad Doubleword (wrap within cache line)
Содержание CPC700
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