PI7C8150BND Pericom Semiconductor, PI7C8150BND Datasheet - Page 41

• Manufacturer Part Number: PI7C8150BND
• Manufacturer: Pericom Semiconductor

Specifications of PI7C8150BND

• Operating Temperature (min): 0C
• Operating Temperature Classification: Commercial
• Operating Temperature (max): 85C
• Package Type: BGA
• Rad Hardened: No
• Lead Free Status / Rohs Status: Not Compliant

4.2.2
4.3
are read/write. After primary bus reset or chip reset, the value of the I/O limit address is
reset to 0000 0FFFh.
Note: The initial states of the I/O base and I/O limit address registers define
an I/O range of 0000 0000h to 0000 0FFFh, which is the bottom 4KB of I/O space. Write
these registers with their appropriate values before setting either the I/O enable bit or the
master enable bit in the command register in configuration space.
ISA MODE
PI7C8150 supports ISA mode by providing an ISA enable bit in the bridge control register
in configuration space. ISA mode modifies the response of PI7C8150 inside the I/O
address range in order to support mapping of I/O space in the presence of an ISA bus in the
system. This bit only affects the response of PI7C8150 when the transaction falls inside the
address range defined by the I/O base and limit address registers, and only when this
address also falls inside the first 64KB of I/O space (address bits [31:16] are 0000h).
When the ISA enable bit is set, PI7C8150 does not forward downstream any I/O
transactions addressing the top 768 bytes of each aligned 1KB block. Only those
transactions addressing the bottom 256 bytes of an aligned 1KB block inside the base and
limit I/O address range are forwarded downstream. Transactions above the 64KB I/O
address boundary are forwarded as defined by the address range defined by the I/O base
and limit registers.
Accordingly, if the ISA enable bit is set, PI7C8150 forwards upstream those I/O
transactions addressing the top 768 bytes of each aligned 1KB block within the first 64KB
of I/O space. The master enable bit in the command configuration register must also be set
to enable upstream forwarding. All other I/O transactions initiated on the secondary bus are
forwarded upstream only if they fall outside the I/O address range.
When the ISA enable bit is set, devices downstream of PI7C8150 can have I/O space
mapped into the first 256 bytes of each 1KB chunk below the 64KB boundary, or anywhere
in I/O space above the 64KB boundary.
MEMORY ADDRESS DECODING
PI7C8150 has three mechanisms for defining memory address ranges for forwarding of
memory transactions:
!
!
!
This section describes the first two mechanisms. Section 4.4.1 describes VGA mode. To
enable downstream forwarding of memory transactions, the memory enable bit must be set
in the command register in configuration space. To enable upstream forwarding of memory
transactions, the master-enable bit must be set in the command register. The master-enable
bit also allows upstream forwarding of I/O transactions if it is set.
CAUTION
Memory-mapped I/O base and limit address registers
Prefetchable memory base and limit address registers
VGA mode
31
March 19, 2003 – Revision 1.04
2-PORT PCI-TO-PCI BRIDGE
ADVANCE INFORMATION
PI7C8150