LSI53C875 LSI Logic, LSI53C875 Datasheet - Page 82

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

3-18
Register: 0x0C
Cache Line Size
Read/Write
CLS
Register: 0x0D
Latency Timer
Read/Write
LT
PCI Functional Description
7
0
7
0
0
0
Cache Line Size
This register specifies the system cache line size in units
of 32-bit words. Cache mode is enabled and disabled by
the Cache Line Size Enable (CLSE) bit, bit 7 in the
Control (DCNTL)
LSI53C875 to align to cache line boundaries before
allowing any bursting, except during Memory Moves in
which the read and write addresses are not aligned to a
burst size boundary. For more information on this regis-
ter, see the section
Line Size Register.”
Latency Timer
The Latency Timer register specifies, in units of PCI bus
clocks, the value of the Latency Timer for this PCI bus
master. The LSI53C875 supports this timer. All eight bits
are writable, allowing latency values of 0–255 PCI clocks.
Use the following equation to calculate an optimum
latency value for the LSI53C875:
Latency = 2 + (Burst Size x (typical wait states +1))
Values greater than optimum are also acceptable.
0
0
0
0
register. Setting this bit causes the
CLS
Section 3.2.1, “Support for PCI Cache
LT
0
0
0
0
0
0
DMA
0
0
0
0
[7:0]
[7:0]