Service manual

System Overview 1-89
The remote I/O riser module provides an interface between a single I/O cable
and two PCI buses.
Figure 1–40 is a block diagram of the remote I/O riser module installed in the
PCI I/O subsystem. The data path passes through the MLK ASIC to the PCA
ASIC that controls the two PCI buses.
Both the MLK ASIC and the PCA ASIC are synchronized to the PCI using a
phase locked loop device that receives its reference clock from the PCI.
The Port In and Port Out signals provide a full duplex link between the MLK
ASIC and the PCA ASIC. The Port signals include 16 address lines, 16 data
lines, and various control lines.
The Cable In and Cable Out signals provide a full duplex link between near end
(local) and far end (remote) MLK ASICs through the I/O cable. The I/O cable
signals include 16 multiplexed address/data lines and various control lines.
A 256x8-bit I
2
C EEPROM present on the module sits on the I
2
C bus controlled
by the PBM on the PCI backplane. The contents of this EEPROM can be read
using the show fru SCM command.
A short-circuit protection (SCP) daughtercard is provided to monitor the +1.5V,
+3.3V, and +3.3V PLL supply rails; it shuts the power down quickly if a short is
detected on the module.