Advantech PCA-6185 user manual System Memory, Memory Installation Procedures

1.8 System Memory

The top-left edge of the PCA-6185 contains three sockets for 184-pin dual inline memory modules (DIMMs). All these sockets accept only 2.5 V registered DDR SDRAM. Registered DIMMs are available in capaci- ties of 128, 256, 512, 1024 or 2048 MB. The sockets can be filled in any combination with DIMMs of any size, with the limitation of the total memory capacity of 4 GB.

1.8.1Sample calculation: DIMM memory capacity

Suppose you install a 128 MB DIMM into your PCA-6185's socket 1 and a 256 MB DIMM into sockets 2 and 3. Your total system memory is 640 MB, calculated as follows:

Table 1.6: DIMM memory capacity sample calculation

Socket number	184-pin DIMM memory	Total memory
1	128 MB x 1	128 MB
2	256 MB x 1	256 MB
3	256 MB x 1	256 MB

Total memory: 640 MB

1.8.2 Supplementary information about DIMMs

Your PCA-6185 can accept only registered DDR SDRAM memory mod- ules. The register on the memory module secures reliable operation of high memory capacity under high speed. Also note:

• Please use only DDR compliant registered DIMMS.

Most systems will not even boot if non-compliant modules are used. This is due to strict timing issues involved at this speed.

•You can find two or three additional register ICs on a registered SDRAM. These ICs are relatively smaller than the SDRAM ICs.

•Registered SDRAM are usually with ECC function. Modules with 9 or 18 SDRAM chips support ECC; modules with 8 or 16 SDRAM chips do not support ECC.

1.9Memory Installation Procedures

To install DIMMs, first make sure the two handles of the DIMM socket are in the "open" position. i.e. The handles lean outward. Slowly slide the DIMM module along the plastic guides on both ends of the socket. Then press the DIMM module right down into the socket, until you hear a click. This is when the two handles have

PCA-6185 User’s Manual 14