82801BA Datasheet, PDF (129/498 Pages) Intel Corporation – Intel 82801BA I/O Controller Hub 2 (ICH2) and Intel 82801BAM I/O Controller Hub 2 Mobile

Functional Description
Table 5-31. INIT# Going Active
Cause of INIT# Going Active
Comment
Shutdown special cycle from the processor.
PORT92 write, where INIT_NOW (bit 0) transitions
from a 0 to a 1.
PORTCF9 write, where RST_CPU (bit 2) was a 0
and SYS_RST(bit 1) transitions from 0 to 1.
RCIN# input signal goes low. RCIN# is expected to 0 to 1 transition on RCIN# must occur before the ICH2
be driven by the external microcontroller (KBC). arms INIT# to be generated again.
Processor BIST
To enter BIST, the software sets CPU_BIST_EN bit and
then does a full processor reset using the CF9 register.
5.11.1.3 FERR#/IGNNE# (Coprocessor Error)
The ICH2 supports the coprocessor error function with the FERR#/IGNNE# pins. The function is
enabled via the COPROC_ERR_EN bit (Device 31:Function 0, Offset D0, bit 13). FERR# is tied
directly to the Coprocessor Error signal of the processor. If FERR# is driven active by the
processor, IRQ13 goes active (internally). When it detects a write to the COPROC_ERR register,
the ICH2 negates the internal IRQ13 and drives IGNNE# active. IGNNE# remains active until
FERR# is driven inactive. IGNNE# is never driven active unless FERR# is active.
Figure 5-12. Coprocessor Error Timing Diagram
FERR#
Internal IRQ13
I/O Write to F0h
IGNNE#
If COPROC_ERR_EN is not set, the assertion of FERR# will not generate an internal IRQ13; the
write to F0h will not generate IGNNE#.
5.11.1.4 NMI
Non-Maskable Interrupts (NMIs) can be generated by several sources, as described in Table 5-32.
Table 5-32. NMI Sources
Cause of NMI
Comment
SERR# goes active (either internally, externally
via SERR# signal, or via message from MCH)
IOCHK# goes active via SERIRQ# stream
(ISA system Error)
Can instead be routed to generate an SCI, through the
NMI2SCI_EN bit (Device 31:Function 0, offset 4E, bit 11).
Can instead be routed to generate an SCI, through the
NMI2SCI_EN bit (Device 31:Function 0, offset 4E, bit 11).
82801BA ICH2 and 82801BAM ICH2-M Datasheet
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