PI7C8150ND Pericom Semiconductor, PI7C8150ND Datasheet - Page 44

• Manufacturer Part Number: PI7C8150ND
• Manufacturer: Pericom Semiconductor

Specifications of PI7C8150ND

• Operating Temperature (min): 0C
• Operating Temperature Classification: Commercial
• Operating Temperature (max): 85C
• Package Type: BGA
• Rad Hardened: No
• Case: BGA
• Dc: 04+
• Lead Free Status / Rohs Status: Not Compliant

4.4
4.4.1
4.4.2
VGA SUPPORT
PI7C8150 provides two modes for VGA support:
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VGA MODE
When a VGA-compatible device exists downstream from PI7C8150, set the VGA mode bit
in the bridge control register in configuration space to enable VGA mode. When PI7C8150
is operating in VGA mode, it forwards downstream those transactions addressing the VGA
frame buffer memory and VGA I/O registers, regardless of the values of the base and limit
address registers. PI7C8150 ignores transactions initiated on the secondary interface
addressing these locations.
The VGA frame buffer consists of the following memory address range:
000A 0000h–000B FFFFh
Read transactions to frame buffer memory are treated as non-prefetchable. PI7C8150
requests only a single data transfer from the target, and read byte enable bits are forwarded
to the target bus.
The VGA I/O addresses are in the range of 3B0h–3BBh and 3C0h–3DFh I/O. These I/O
addresses are aliases every 1KB throughout the first 64KB of I/O space. This means that
address bits <15:10> are not decoded and can be any value, while address bits [31:16] must
be all 0’s. VGA BIOS addresses starting at C0000h are not decoded in VGA mode.
VGA SNOOP MODE
PI7C8150 provides VGA snoop mode, allowing for VGA palette write transactions to be
forwarded downstream. This mode is used when a graphics device downstream from
PI7C8150 needs to snoop or respond to VGA palette write transactions. To enable the
mode, set the VGA snoop bit in the command register in configuration space. Note that
PI7C8150 claims VGA palette write transactions by asserting DEVSEL_L in VGA snoop
mode.
When VGA snoop bit is set, PI7C8150 forwards downstream transactions within the 3C6h,
3C8h and 3C9h I/O addresses space. Note that these addresses are also forwarded as part of
the VGA compatibility mode previously described. Again, address bits <15:10> are not
decoded, while address bits <31:16> must be equal to 0, which means that these addresses
are aliases every 1KB throughout the first 64KB of I/O space.
Note: If both the VGA mode bit and the VGA snoop bit are set, PI7C8150 behaves in the
same way as if only the VGA mode bit were set.
VGA mode, supporting VGA-compatible addressing
VGA snoop mode, supporting VGA palette forwarding
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March 19, 2003 – Revision 1.04
2-PORT PCI-TO-PCI BRIDGE
ADVANCE INFORMATION
PI7C8150