5. Each Component Function
74
User’s Manual
* 4001h (bit4-6): Alarm out output control (See P77 for bits 0 to 3.)
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WD_S0
R/W (default: XXXX0000b)
WD_S1
PO2_M
PIM2
PIM1
PIM0
RESET
D6
D5
D4
D3
D2
D1
D0
D7
Figure 5.5. Alarm Out Output Control Port (4001h)
PO2_M : PO PO2/WDT pin output setting
0 : Set the RAS connector's PO2/WDT(12) signal to PO2 (general-purpose output).
1 : Set the RAS connector's PO2/WDT(12) signal to alarm out.
*1 When "WDT Output to PO2" in the "Advanced Chipset Features Setup" menu in BIOS Setup is set
to:
"Disabled" (default): The PO2_M bit is set to 0.
"Enabled": The PO2_M bit is set to 1.
Table 5.15. WD_S1, WD_S0: Alarm-out Output Status Settings
External alarm output status
WD_S1
*2
WD_S0
*3
When power is
turned off
When BIOS
starts
When
WDT starts
When time
expires on WDT
0
0
OFF
OFF
OFF
ON
1
0
OFF
OFF
ON
OFF
1
1
OFF
ON
ON
OFF
0
1
OFF
ON
OFF
ON
*2
When "WDT Power-on State" in the "Advanced Chipset Features Setup" menu in BIOS Setup is set to:
"Off" (default): The WD_S0 bit is set to 0.
"On": The WD_S0 bit is set to 1.
*3
When "WDT Time-up State" in the "Advanced Chipset Features Setup" menu in BIOS Setup is set to:
"Off": The WD_S1 bit is set to 1.
"On (default)": The WD_S2 bit is set to 0.
* 4002h WDT control
R/W
D6
D5
D4
D3
D2
D1
D0
D7
Figure 5.6. WDT Control Port (4002h)
R
: Cancels WDT stop/alarm.
Read data is undefined.
W : Start and clear the WDT.
Write A5h to start and clear the WDT.
