EP80579 Datasheet, PDF (1099/1916 Pages) Intel Corporation – Intel® EP80579 Integrated Processor Product Line

Intel^® EP80579 Integrated Processor
28.1.1.2
Note:
Offset 70h: NMI_EN - NMI Enable (and Real Time Clock Index)
Register
This register is write-only for normal operation. In Alt-Access mode, this register can be
read to find the NMI Enable status and the RTC index value.
The RTC Index field is write-only for normal operation. This field can only be read in Alt-
Access Mode. Note, however, that this register is aliased to Port 74h and all bits are
readable at that address. See Section 29.2, “RTC I/O Registers” for more information.
Table 28-4. Offset 70h: NMI_EN - NMI Enable (and Real Time Clock Index) Register
Description:
View: IA F
Base Address: 0000h (IO)
Offset Start: 70h
Offset End: 70h
Size: 8 bit
Default: 80h
Power Well: Core
Bit Range
07
06 : 00
Bit Acronym
Bit Description
Sticky
NMI_EN
RTC_INDX
NMI Enable:
0 = NMI sources are enabled.
1 = All NMI sources are disabled.
Real Time Clock Index (Address):This data goes to the
RTC to select which register or CMOS RAM address is
being accessed.
Bit Reset
Value
1b
0000000b
Bit Access
RWS
RWS
Note:
Software must preserve the value of bit 7 at I/O addresses 70h. When writing to this
address, software must first read the value, and then write the same value for bit 7
during the sequential address write. Note that port 70h is not directly readable. The
only way to read this register is through Alt Access mode. Although RTC Index bits
06:00 are readable from port 74h, bit 7 will always return 0. If the NMI# enable is not
changed during normal operation, software can alternatively read this bit once and
then retain the value for all subsequent writes to port 70h.
August 2009
Order Number: 320066-003US
Intel^® EP80579 Integrated Processor Product Line Datasheet
1099