12. Register Descriptions
354
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
BS:
Specifies the size of the image, address lines compared and address lines translated.
PRKEEP
R/W
PRI_RST
0
Prefetch Read Keep Data
This bit is used to hold read data is fetched beyond the initial
PCI read cycle. When set, subsequent read requests to the
same image at the next address retrieves the read data
directly from the switching fabric instead of causing the
destination bus to fetch more data. The read data is
invalidated when a read with a non-matching address
occurs.
0 = Disable
1 = Enable
END[1:0]
R/W
PRI_RST
10b
Endian Conversion Mode
This selects the endian conversion mode.
00 = Little-endian
01 = PowerPC little-endian
10 = Big-endian
11 = True little-endian
MRA
R/W
PRI_RST
0
PCI Memory Read Alias to MRM
When set, the PCI I2O Target Image will alias a PCI Memory
Read cycle to a PCI Memory Read Multiple cycle and
prefetches the number of bytes specified in the
RD_AMT[2:0] field. When MRA is the Target Image
prefetches 8 bytes when a PCI Memory Read cycle is
decoded and claimed.
0 = Disabled
1 = Enabled
RD_AMT[2:0]
R/W
PRI_RST
0
Prefetch Size
Specifies the number of bytes the device will prefetch for
PCI Memory Read Multiple transactions claimed by the
target image (see
)
Table 82: Block Size
BS[3:0]
Block Size
Address Lines Compared/Translated
0000
64k
AD31-AD16
0001
128K
AD31-AD17
0010
256K
AD31-AD18
0011
512K
AD31-AD19
0100
1M
AD31-AD20
Name
Type
Reset
By
Reset
State
Function