Preparing for the Installation
1–13
1.6 Identifying the VME Chassis and Backplane Slots
Before you can begin the installation, you must have a VME chassis with at least
two adjacent empty backplane slots. If you need to use the optional PMC I/O
companion card, the chassis must have three adjacent empty slots. Once you
locate a chassis with the required empty slots, identify the slots to be used for the
installation.
1.6.1 VME Chassis Requirements
The Alpha VME 5/352 and 5/480 SBCs provide a heat sink for CPU thermal con-
trol. The amount of cooling required is defined by the operating environment to
which the SBC assembly is subjected. The curves shown in Figure 1–8 define the
amount of ambient air the SBC assembly requires in linear feet per minute at vari-
ous ambient temperatures. Actual cooling depends on the turbulence in the air
stream as it enters the assembly volume. If you operate your Alpha 5/352 or 5/480
SBC in an enclosure that is not fully assembled, be sure the air flow to and around
the SBC meets or exceeds the requirements indicated by the curves.
Figure 1–8 Required Air Flow Relative to Ambient Temperature
Note
The maximum temperature, when measured between the heat sink studs
on the base of the heat sink, must be less than 68 C.
1.6.2 Backplane Considerations
Alpha VME 5/352 and 5/480 SBCs provide CPU and I/O functionality through a
2-module configuration. The VMEbus functions are generated on the I/O module.
This module occupies the
n
+1 backplane slot, which is to the immediate right of
the slot occupied by the CPU module. To ensure proper operation of the 2-mod-
ule configuration, you must address the backplane considerations discussed in
°