
2-10 Functional Description
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2.3.1.3 PCI Memory Space
The LSISAS1064 contains two PCI memory spaces: PCI Memory
Space [0] and PCI Memory Space [1]. PCI Memory Space [0] supports
normal memory accesses while PCI Memory Space [1] supports
diagnostic memory accesses. The LSISAS1064 requires 64 Kbytes of
memory space.
The PCI specification defines memory space as a contiguous 64-bit
memory address that all system resources share. The Memory [0] Low
and Memory [0] High registers determine which 64 Kbyte memory area
PCI Memory Space [0] occupies. The Memory [1] Low and Memory [1]
High registers determine which 64 Kbyte memory area PCI Memory
Space [1] occupies.
2.3.2 PCI Commands and Functions
Bus commands indicate to the target the type of transaction the master
is requesting. The master encodes the bus commands on the C_BE[3:0]/
lines during the address phase. The PCI bus command encodings
appear in Table 2.1.
Table 2.1 PCI/PCI-X Bus Commands and Encodings
1
C_BE[3:0]/ PCI Command PCI-X Command
Supports
as Master
Supports
as Slave
0b0000 Interrupt Acknowledge Interrupt Acknowledge No No
0b0001 Special Cycle Special Cycle No No
0b0010 I/O Read I/O Read Yes Yes
0b0011 I/O Write I/O Write Yes Yes
0b0100 Reserved Reserved N/A N/A
0b0101 Reserved Reserved N/A N/A
0b0110 Memory Read Memory Read Dword Yes Yes
0b0111 Memory Write Memory Write Yes Yes
0b1000 Reserved Alias to
Memory Read Block
PCI: N/A
PCI-X: No
PCI: N/A
PCI-X: Yes
0b1001 Reserved Alias to
Memory Write Block
PCI: N/A
PCI-X: No
PCI: N/A
PCI-X: Yes
0b1010 Configuration Read Configuration Read No Yes
0b1011 Configuration Write Configuration Write No Yes
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