Intel 460GX 11.2.6Advanced Power Management (APM) Registers, 11.2.6.1APMC–AdvancedPower Management Control Port (I/O)

LPC/FWH Interface Configuration

11.2.5.3RTCEI–Real-time Clock Extended Index Register (I/O)

I/O Address:	072h
Default Value:	Unknown
Attribute:	Write Only

The index port for accesses to the RTC extended RAM bank.

Bit Description

7 Reserved.

6:0 Real Time Clock Extended Address. Latched by the Real Time Clock to address memory locations within the extended RAM bank accessed via the Real Time Clock Extended Data Register (073h).

11.2.5.4RTCED–Real-time Clock Extended Data Register (I/O)

I/O Address:	073h
Default Value:	Unknown
Attribute:	Read/Write

The data port for accesses to the RTC extended RAM bank.

Bit Description

7:0 Extended RAM Data Port. Data written to standard RAM bank address selected via RTC Extended Index Register (072h).

11.2.6Advanced Power Management (APM) Registers

This section describes two power management registers–APMC and APMS Registers. These registers are located in normal I/O space and must be accessed (via the PCI Bus) with 8 bit accesses.

11.2.6.1APMC–Advanced Power Management Control Port (I/O)

I/O Address:	0B2h
Default Value:	00h
Attribute:	Read/Write

This register passes data (APM Commands) between the OS and the SMI handler. In addition, writes can generate an SMI. The IFB operation is not effected by the data in this register.

Bit Description

7:0 APM Control Port (APMC). Writes to this register store data in the APMC Register and reads return the last data written. In addition, writes generate an SMI, if the APMC_EN bit (PCI Function 3, offset58h, bit 25) is set to 1. Reads do not generate an SMI.

11-30 Intel® 460GX Chipset Software Developer’s Manual