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The electrical characteristics of the RAM DIMM are given in section 4.5.6 of the JEDEC Standard 21-C. The specification is available from the Electronics Industry Association's web site, at
http://www.jedec.org/download/freestd/pub21/
The specification defines several attributes of the DIMM, including storage capacity and configuration, connector pin assignments, and electrical loading.
The presence detect serial EEPROM specified in the JEDEC standard is required and must be set to properly define the DIMM configuration. Details about the required values to be stored in the presence detect EEPROM can be found in sections 4.5.4 and 4.1.2.5 of the JEDEC standard 21-C specification.
The RAM DIMMs are required to be the PC-100 compliant. The PC-100 specification is available from Intel's web site, at
http://developer.intel.com/design/chipsets/memory/sdram.htm#S1
The SDRAM devices used in the RAM expansion modules must be self-refresh type devices for operation from a 3.3-V power supply. The speed of the SDRAM devices must be 125 MHz or greater, corresponding to a cycle time of 8 ns or less, as required by the PC-100 specification.