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Intel® 460GX Chipset Software Developer’s Manual 11-5
LPC/FWH Interface Configuration
11.1.11 BIOSEN–BIOS Enable Register (FUNCTION 0)
Address Offset: 4E-4Fh
Default Value: 07C1h
Attribute: Read/Write
This register is used to implement protections to writes to firmware (BIOS) ranges.
11.1.12 PIRQRC[A:D]–PIRQx Route Control Registers (Function 0)
Address Offset: 60h (PIRQRCA#)–63h (PIRQRCD#)
Default Value: 80h
Attribute: R/W
These registers control the routing of the PIRQ[A:D]# signals to the IRQ inputs of the interrupt
controller. Each PIRQx# can be independently routed to any one of 11 interrupts. All four PIRQx#
lines can be routed to the same IRQx input. Note that the IRQ that is selected through bits [3:0]
must be set to level sensitive mode in the corresponding ELCR Register. When a PIRQ signal is
routed to an interrupt controller IRQ, the IFB masks the corresponding IRQ signal.
Bit Description
15 BLE - BIOS Lock Enable: When the bit is a “1”, setting BIOS_WEN bit will cause SMIs. When this
bit is a “0”, setting BIOS_WEN will not cause SMIs. Once set, this bit can only be cleared by a
PCIRST#.
14:11 Reserved.
10:3 Reserved. Software must preserve these register values.
2 BIOS_WEN - BIOS Write Enable. When this bit is set to a “1”, writes to firmware (BIOS) ranges
are allowed. When this bit is a “0”, writes to firmware (BIOS) ranges are not allowed and write
cycles will be master-aborted on PCI. There is no protection on writes to FWH register space.
When this bit is written from a “0” to a “1”, and bit 15 (BIOS Lock Enable) is set, an SMI# is
generated.
1:0 Reserved. Software must preserve these register values.
Bit Description
7 Interrupt Routing Enable. When this bit is a “0”, the corresponding PIRQ is routed to one of the
compatibility mode interrupts specified in bits[3:0]. When this bit is a “1”, the PIRQ is not routed.
6:4 Reserved.
3:0 Interrupt Routing. When bit 7=0, this field selects the routing of the PIRQx to one of the interrupt
controller interrupt inputs.
Bits[3:0]
0000
0001
0010
0011
0100
0101
IRQ Routing
Reserved
Reserved
Reserved
IRQ3
IRW4
IRQ5
Bits[3:0]
0110
0111
1000
1001
1010
IRQ Routing
IRQ6
IRQ7
Reserved
IRQ9
IRQ10
Bits[3:0]
1011
1100
1101
1110
1111
IRQ Routing
IRQ11
IRQ12
Reserved
IRQ14
IRQ15