2. PCI Interface
48
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
A new request for access to the bus is generated by the PowerSpan II PCI Master when it requires
access to the PCI bus to service a request from the Processor Bus Interface or the other PCI interface
(Py). After the request is generated by PowerSpan II, it successfully arbitrates for access to the PCI bus
when it receives GNT_ from the arbiter. PowerSpan II then asserts Px_FRAME# to indicate the
beginning of a transaction.
Table 7: Command Encoding for Transaction Type (PowerSpan II as PCI Master)
Px_C/BE# [3:0]
Transaction Type
PowerSpan II Capable
0000
Interrupt Acknowledge
Yes (see
)
0001
Special Cycle
No
0010
I/O Read
Yes
0011
I/O Write
Yes
0100
Reserved
N/A
0101
Reserved
N/A
0110
Memory Read
Yes
0111
Memory Write
Yes
1000
Reserved
N/A
1001
Reserved
N/A
1010
Configuration Read
Yes (see
)
1011
Configuration Write
Yes (see
)
1100
Memory Read Multiple
Yes
1101
Dual Address Cycle
No
1110
Memory Read Line
Yes
1111
Memory Write and Invalidate
(The MWI_EN bit is
hard-wired to “0” in the
“PCI-1 Control and Status
Register.” on page 251
No