82801BA Datasheet, PDF (127/498 Pages) Intel Corporation – Intel 82801BA I/O Controller Hub 2 (ICH2) and Intel 82801BAM I/O Controller Hub 2 Mobile

Functional Description
Table 5-30. Configuration Bits Reset By RTCRST# Assertion
Bit Name
FREQ_STRAP[3:0]
AIE
AF
PWR_FLR
AFTERG3_EN
RTC_PWR_STS
PRBTNOR_STS
PME_EN
RI_EN
NEW_CENTURY_STS
INTRD_DET
TOP_SWAP
RTC_EN
BATLOW_EN
(ICH2-M only)
Register
GEN_STS
RTC Reg B
RTC Reg C
GEN_PMCON_3
GEN_PMCON_3
GEN_PMCON_3
PM1_STS
GPE0_EN
GPE0_EN
TCO1_STS
TCO2_STS
GEN_STS
PM1_EN
GPE0_EN
Location
D31:F0:D4h
I/O space
I/O space
D31:F0:A4h
D31:F0:A4h
D31:F0:A4h
PMBase + 00h
PMBase + 2Ah
PMBase + 2Ah
TCOBase + 04h
TCOBase + 06h
D31:F0:D4h
PMBase + 02h
PMBase + 2Ah
Bits Default Value
11:8
1111b
5
0
5
0
1
0
0
0
2
1
11
0
11
0
8
0
7
0
0
0
13
0
10
0
10
0
Using a GPI to clear CMOS
A jumper on a GPI can also be used to clear CMOS values. BIOS detects the setting of this GPI on
system boot-up and manually clear the CMOS array.
Using the SAFEMODE Strap to clear CMOS
A jumper on AC_SDOUT (SAFEMODE strap) can also be used to clear CMOS values. BIOS
detects the setting of the SAFE_MODE status bit (D31:F0: Offset D4h bit 2) on system boot-up,
and manually clear the CMOS array.
Note:
Both the GPI and SAFEMODE strap techniques to clear CMOS require multiple steps to
implement. The system is booted with the jumper in a new position, then powered back down. The
jumper is replaced back to the normal position, then the system is rebooted again. The RTCRST#
jumper technique allows the jumper to be moved and then replaced, all while the system is
powered off. Then, once booted, the RTC_PWR_STS can be detected in the set state.
Note: Clearing CMOS, using a jumper on VCCRTC, must NOT be implemented.
82801BA ICH2 and 82801BAM ICH2-M Datasheet
5-65