12. Register Descriptions
305
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
ARTRY_EN:
Controls PowerSpan II’s use of PB_ARTRY_ during the servicing of transactions.
When ARTRY_EN is set, the Processor Bus Slave retries a processor (60x) bus master under the
following conditions:
•
Register write while an external master connected to another PowerSpan II interface is doing a
register write
•
Register read during I
2
C load
•
Posted write when no buffers are available
•
Read from PCI-1 or PCI-2
MODE_7400
R/W
PB_RST
1
Determines if PowerSpan II Processor Bus Slave can accept
misaligned data transfers defined for PowerPC 7400. Refer
to
for a complete list of data transfers
supported by PowerSpan II.
0 = cannot accept PowerPC 7400 misaligned transfers
1 = can accept PowerPC 7400 misaligned transfers
TEA_EN
R/W
PB_RST
1
Suppress PB_TEA_ generation
When this bit is cleared, PowerSpan II never asserts TEA_.
Error conditions are signalled exclusively with interrupts.
0 = PowerSpan II does not assert PB_TEA_
1 = PowerSpan II asserts PB_TEA_
ARTRY_EN
R/W
PB_RST
0
Address Retry Enable
0 = PB Slave never asserts PB_ARTRY_
1 = PB Slave asserts PB_ARTRY_ as required
DP_EN
R/W
PB_RST
0
Data Parity Enable
When cleared, the PowerSpan II does not check the parity
pins for the proper parity value. PowerSpan II still drives out
parity on master writes and slave read cycles. Parity checking
is disabled by default.
0 = Data parity checking disabled
1 = Data parity checking enabled
AP_EN
R/W
PB_RST
0
Address Parity Enable
When cleared, the PowerSpan II does not check the parity
pins for the proper parity value. PowerSpan II still drives out
parity on master writes and slave read cycles. Parity checking
is disabled by default.
0 = Address parity checking disabled
1 = Address parity checking enabled
PARITY
R/W
PB_RST
0
Parity
0 = Odd Parity
1 = Even Parity
Name
Type
Reset
By
Reset
State
Function