LSI53C875 LSI Logic, LSI53C875 Datasheet - Page 112

• Manufacturer Part Number: LSI53C875
• Description: PCI to Ultra SCSI I/O Processor
• Manufacturer: LSI Logic

Table 4.10
4-20
Name
BIG_LIT/ (Not
available on
LSI53C875J,
LSI53C875JB)
Additional Interface Signals (Cont.)
LSI53C875JB Type Description
LSI53C875N,
LSI53C875J,
LSI53C875,
NA/184/NA
Signal Descriptions
Pin No.
142,
I
Big_Little Endian Select. When this pin is driven LOW,
the LSI53C875 routes the first byte of an aligned SCSI to
PCI transfer to byte lane zero of the PCI bus and
subsequent bytes received are routed to ascending lanes.
An aligned PCI to SCSI transfer routes PCI byte lane zero
onto the SCSI bus first, and transfers ascending byte lanes
in order. When this pin is driven HIGH, the LSI53C875
routes the first byte of an aligned SCSI-to-PCI transfer to
byte lane three of the PCI bus and subsequent bytes
received are routed to descending lanes. An aligned
PCI-to-SCSI transfer routes PCI byte lane three onto the
SCSI bus first and transfers descending byte lanes in
order. This mode of operation also applies to the external
memory interface. When this pin is driven in little endian
mode and the chip is performing a read from external
memory, the byte of data accessed at location 0x00000 is
routed to PCI byte lane zero and the data accessed at
location 0x00003 is routed to PCI byte lane three. When
the chip is performing a write to Flash memory, PCI byte
lane zero is routed to location 0x00000 and ascending byte
lanes are routed to subsequent memory locations. When
this pin is driven in big endian mode and the chip is
performing a read from external memory, the byte of data
accessed at location 0x00000 is routed to PCI byte lane
three and the data accessed at location 0x00003 is routed
to byte lane zero. When the chip is performing a write to
Flash memory, PCI byte lane three is routed to location
0x00000 and descending byte lanes are routed to
subsequent memory locations.