How is PC100 memory different from other SDRAM modules

How is PC100 memory different from other SDRAM modules?

Aside from one or two changes to the pinout specification, the biggest difference is that PC100 adds design requirements that ensure proper timing. The previous standard had maximum length specifications for many of the circuit paths while PC100 adds a 'Minimum' specification.

Other key changes include trace width and spacing, layer spacing, power and ground plane integrity, precise clock trace matching, use of specially qualified 'PC100 Compliant' SDRAM chips, and SPD programming.

Aside from the SPD program changes and qualified chips, most of the PC 100 specifications are part of any design made by engineering a module with a firm understanding of digital electronics design and how the memory is meant to interact with the system.

Some memory vendors reverse-engineer someone elses module by shifting the component positioning without paying attention to the physics involved with such extreme performance as 100MHz operation. The PC 100 specs are more a lesson in engineering than a dramatic change in how the memory works.

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