It is possible to identify the chips by part number. You have to identify the size of each the chips on a module, and then multiply the size by the number of chips on the module to determine its memory capacity.

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Different RAM manufacturers have developed their own methods of identification, so it is has become difficult to identify the chips without looking up the exact part number on a website that provides the information.

Unless they have been remarked by unscrupulous dealers that are selling substandard modules not passed for use in a computer as computer-quality, all of the chips on a particular module will have the manufacturer's name (or logo), and a part number printed on them.

For example, a 30-pin SIMM module with nine chips on the module, could have the part number - KM41C4000AJ-8. Drop the AJ-8 (the first letter is usually the quality - A, B, C, etc.), then use KM41C4000 to conduct a Google search. You should be provided with links to many sites that provide information about part numbers. One of them is http://www.memoryusa.com/guide.html.

The KM indicates parts made by Samsung. The 41 indicates that it is a 1Mbit x 4 part. This means that the chip holds 4Mbits. Eight of the nine chips hold memory, so this is a 8 x 4Mbit, or 32Mbit module. There are eight bits to a byte, therefore this is an 4MB module. The ninth chip is there to add parity. This was used as a means of checking for memory errors that is no longer used.

For a 168-pin DIMM module that has eight chips (no parity chip), and the part number - TMS626812DGE-12A - you would use TMS626812 to search for information on it.

Each chip is a 2Mbit x 8 (16Mbit) SDRAM chip. There are eight chips, so this is a 16MB SDRAM module, which is slow compared to the fastest speed that SDRAM modules reached. The 12 in the part number indicates that the module has a maximum frequency (speed) of 66MHz. SDRAM modules, now superseded by DDR and Rambus RAM, reached a maximum speed of 133MHz.

Decode RAM chip part numbers

At the following site, you just enter the RAM chip part numbers to find out the manufacturer and specifications. -

http://www.chipmunk.nl/DRAM/ChipManufacturers.htm