82C836 Datasheet, PDF (116/205 Pages) List of Unclassifed Manufacturers – Single-Chip 386sx AT

s Configuration Registers
82C386 CHIPSet Data Sheet
Table 10-5. Index 45H----Miscellaneous Status, Read Only
Bit
Name
Description
7
NMI Inhibit
This bit indicates the current state of the NMI inhibit bit of I/O Port 70H,
bit 7. Bit 7 of I/O port 70H is write only.
0 = NMI enabled.
1 = NMI disabled (port 70 is default).
6
GATEA20 From This bit indicates the current state of the GATEA20 input from the 8042
8042
keyboard controller.
5
Busy to CPU
This bit indicates the current state of the latched busy signal to the 80386sx.
0 = BUSY signal low.
1 = BUSY signal high.
4
Internal RTC
This bit indicates the state of the -EXRTC (-DACK5) pin during reset.
Enabled
0 = External RTC used (XD bus).
1 = Internal RTC used.
3
-NA/-STCYC
Normally the -NA pin is used as an -NA and/or -ADRL signal. For external
Select
cache support, it can be changed to operate as a CPU cycle start (-STCYC)
and/or address latch (-ADRL) signal.
0 = -STCYC/-ADRL function
1 = -NA/-ADRL function
The state of this bit is determined by the state of -DACK3 during reset.
-DACK3 should be pulled up if -NA goes to the CPU.
2-0
Sense Lines 2-0
These lines (2-0) sense the power-up state of DACK lines (2-0), respectively
(noninverted). These lines can be used for power-up setup parameters.
-DACK2 (inverted) also determines the power-up state of ICR 44H bit 6.
0 = Corresponding DACK line pulled low.
1 = Corresponding DACK line pulled high.
A 4.7K ohm resistor is recommended for the pull-up or pull-down.
Index 46H controls sleep mode and PROCCLK frequency for power conservation.
Table 10-6. Index 46H----Power Management
Bit
Name
7
Sleep Enable
Description
This bit enables sleep mode. If this bit is set, sleep mode will be entered
upon execution of a HALT instruction. An interrupt (INTR or NMI) will
terminate sleep mode until a subsequent HALT; a DMA or refresh will
terminate sleep mode temporarily, then return to sleep mode upon
completion of the DMA or refresh.
0 = Sleep mode disabled (default).
1 = Sleep mode enabled.
1 0-4 Revision 3.0
PRELIMINARY
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