AMD SC2200 manual Index 42h, Index 43h, Reset Control Register R/W Reset Value 01h, 202

32580B Core Logic Module - Bridge, GPIO, and LPC Registers - Function 0

Table 6-29. F0: PCI Header/Bridge Configuration Registers for GPIO and LPC Support (Continued)

Bit Description

0Legacy Configuration Trap. If this bit is set to 1 and an access occurs to one of the configuration registers in PCI Function 0 (F0), an SMI is generated. Reads and writes are snooped; access to the register is allowed.

0:Disable.

1:Enable.

Top level SMI status is reported at F1BAR0+I/O Offset 00h/02h[9].

Second level SMI status is reported at F1BAR0+I/O Offset 04h/06h[5].

Index 42h	Reserved	Reset Value: 00h
Index 43h	Delayed Transactions Register (R/W)	Reset Value: 02h
7:6	Reserved. Must be set to 0.
5	Reserved. Must be set to 1.

4Enable PCI Delayed Transactions for Access to I/O Address 170h-177h (Secondary IDE Channel). PIO mode uses repeated I/O transactions that are faster when non-delayed transactions are used.

0:I/O addresses complete as fast as possible on PCI. (Default)

1:Accesses to Secondary IDE channel I/O addresses are delayed transactions on PCI.

For best performance of VIP, this bit should be set to 1 unless PIO mode 3 or 4 are used.

3Enable PCI Delayed Transactions for Access to I/O Address 1F0h-1F7h (Primary IDE Channel). PIO mode uses repeated I/O transactions that are faster when non-delayed transactions are used.

0:I/O addresses complete as fast as possible on PCI. (Default)

1:Accesses to Primary IDE channel I/O addresses are delayed transactions on PCI.

For best performance of VIP, this bit should be set to 1 unless PIO mode 3 or 4 are used.

2Enable PCI Delayed Transactions for AT Legacy PIC I/O Addresses. Some PIC status reads are long. Enabling delayed transactions help reduce DMA latency for high bandwidth devices like VIP.

0:PIC I/O addresses complete as fast as possible on PCI. (Default)

1:Accesses to PIC I/O addresses are delayed transactions on PCI.

For best performance of VIP, this bit should be set to 1.

1Enable PCI Delayed Transactions for AT Legacy PIT I/O Addresses. Some x86 programs (certain benchmarks/diagnos- tics) assume a particular latency for PIT accesses; this bit allows that code to work.

0:PIT I/O addresses complete as fast as possible on PCI.

1:Accesses to PIT I/O addresses are delayed transactions on PCI. (Default)

	For best performance (e.g., when running Microsoft Windows®), this bit should be set to 0.
0	Reserved. Must be set to 0.
Index 44h	Reset Control Register (R/W)	Reset Value: 01h

7AC97 Soft Reset. Active low reset for the AC97 codec interface.

0:AC97_RST# is driven high. (Default)

1:AC97_RST# is driven low.

6:4 Reserved. Must be set to 0.

3IDE Controller Reset. Reset the IDE controller.

0:Disable.

1:Enable.

Write 0 to clear. This bit is level-sensitive and must be cleared after the reset is enabled.

202 AMD Geode™ SC2200 Processor Data Book