www.national.com
170
Revision 1.1
G
Core Logic Module
(Continued)
Index 43h
Delayed Transactions Register (R/W)
Reset Value: 02h
7:5
4
Reserved.
Must be set to 0.
Enable 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.
Enable 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.
Enable 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.
3
2
1
Enable 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.
Reserved.
Must be set to 0.
0
Index 44h
Reset Control Register (R/W)
Reset Value: 01h
7
AC97 Soft Reset.
Active high reset for the AC97 codec interface.
0: AC97_RST# (ball AF23) is driven high. (Default)
1: AC97_RST# (ball AF23) is driven low.
Reserved.
Must be set to 0.
IDE 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.
IDE Reset.
Reset IDE bus.
0: Disable.
1: Enable (drives outputs to zero).
Write 0 to clear. This bit is level-sensitive and must be cleared after the reset is enabled.
PCI Reset.
Reset PCI bus.
0: Disable.
1: Enable.
When this bit is set to 1, the Core Logic module output signal PCIRST# is asserted and all devices on the PCI bus (including
PCIUSB) are reset. No other function within the Core Logic module is affected by this bit.
Write 0 to clear this bit. This bit is level-sensitive and must be cleared after the reset is enabled.
X-Bus Warm Start.
Writing and reading this bit each have different meanings.
When reading this bit, it indicates whether or not a warm start occurred since power-up:
0: A warm start occurred.
1: No warm start has occurred.
When writing this bit, it can be used to trigger a system-wide reset:
0: No effect.
1: Execute system-wide reset (used only for clock configuration at power-up).
6:4
3
2
1
0
Index 45h
Reserved
Reset Value: 00h
Table 5-29. F0: PCI Header and Bridge Configuration Registers for GPIO and LPC Support (Continued)
Bit
Description