1-34
1.12
Maintenance Bus (I
2
C Bus)
The I
2
C bus (referred to as the “I squared C bus”) is a small internal
maintenance bus used to monitor system conditions scanned by the power
control module, write the fault display, store error state, and track
configuration information in the system. Although all system modules (not I/O
modules) sit on the maintenance bus, only the I
2
C controller accesses it.
Figure 1-17 I
2
C Bus Block Diagram
PKW0511-97
Memory
Pairs
CPU 0
IOD 1
PCI 1
PCI 0
IOD 0
PCM
Registers
Mother-
board
OCP
Controller
I C Bus
2
I C Bus
Controller
2
XBUS
ISA
PCI0
IOD0
MEMs
CPUs
1
up to 8
