Preparing for the Installation
1–7
1.4.4 Memory Modules
The Alpha VME 5/352 and 5/480 SBCs support memory configurations that
range from 16 to 512 MB of dynamic random access memory (DRAM). This
memory is accessible from the CPU, PCI bus, and VMEbus.
You can plug either two or four dual integrated memory modules (DIMMs), rang-
ing from 8 MB to 128 MB, into the memory connectors on the CPU module. Fig-
ure 1–4 shows a typical memory module.
Figure 1–4 Memory Module
The number of DIMMs you use determines the memory bus bandwidth, and con-
sequently the overall speed of data write and read operations to and from memory.
Force Computers recommends that you use four DIMMs to achieve maximum
performance. No jumper changes are required. The system automatically config-
ures memory based on the DIMMs you install. The following table shows the
width of the memory bus and its performance when you use two and four DIMMs:
Error correction code (ECC) is provided for single-bit errors and error detection is
provided for double-bit errors. For details on how the operating system reports
and handles ECC errors, see your operating system documentation.
In addition to the requirement of using either two or four DIMMs, all DIMMs you
use must be identical in size (number of MB), speed, and architecture (EDO).
Note
Memory DIMMs for the Alpha VME 5/352 and 5/480 are supplied in
pairs. To ensure proper operation of your SBC, you must install the
DIMMs as supplied pairs in memory connectors 0 and 1 or 2 and 3. If you
choose to use only two DIMMs, you must populate memory connectors 0
and 1.
Number of DIMMs
Bus Width
Memory Bandwidth
2
128 bits
210 MB/s
4
256 bits
355 MB/s
ML013783
