12. Register Descriptions
289
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
PB_RST
0
EEPROM
Prefetch Read Keep
Prefetch Read Keep stores prefetch data beyond an initial
read. 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 either PCI bus to
fetch more data. The read data is invalidated when a read
with a non-matching address occurs
0 = purge read data at end of transfer
1 = keep read data
Caution: The ARTRY_EN bit must be set to 1 in order for the
PowerSpan II Prefetch Keep feature to keep prefetched data.
The ARTRY_EN bit is in the
Control and Status Register” on page 304
END[1:0]
R/W
P1_RST
10b
EEPROM
Endian Conversion Mode
Selects the endian mapping.
00 = Little-endian
01 = PowerPC little-endian
10 = Big-endian
11 = True little-endian
RD_AMT
[2:0]
R/W
PB_RST
0
EEPROM
Read Prefetch Amount
Amount of read data fetched from PCI.
If PRKEEP is not set, it is recommended limiting the RD_AMT
to 32-bytes (see
If the slave image is programmed to be in IO mode (the
MODE bit in the
“Processor Bus Slave Image x Control
set to 1 then the RD_AMT is not used
and a maximum of 4 bytes will be read from the PCI bus.
Table 73: Block Size
BS[4:0]
Block Size
Address Lines Compared/Translated
00000
4k
A0-A19
00001
8k
A0-A18
00010
16k
A0-A17
00011
32k
A0-A16
00100
64k
A0-A15
00101
128k
A0-A14
Name
Type
Reset
By
Reset
State
Function