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FREQUENTLY ASKED QUESTIONS
Memory

Last updated: 9/25/00

Q.  What is a SIMM?

A.  A Single In-line Memory Module or SIMM is a small printed circuit board containing memory chips (DRAMs).   Most SIMMs have 30 or 72 pins (which are actually printed circuit contacts and not pins).  30-pin SIMMs come in  8-bit (non-parity) or 9-bit (parity).  72-pin SIMMs are generally available in  32-bit (non-parity) or 36-bit (parity) configurations.

Q.  What is a DIMM?

A.  A Dual In-line Memory Module or DIMM combines two 72-pin SIMMS into a 168-pin module with 64-bit (non-parity) or 72-bit (parity) data paths.

Q. Will PC133 or PC100 memory work on a motherboard that has a 66 Mhz Front Side Bus (FSB)?

A. Let me answer that with a qualified YES.  In general, SDRAM is backward compatible and can run at bus speeds slower than that for which it is rated. For example, the 128 Mbytes of PC133 memory I have in my computer with an EpoX MVP3G2 Super 7 motherboard, which supports PC100 memory, works with a 100 Mhz FSB.. There are a few older 66 Mhz motherboards that will not work PC100 or PC133 memory, but they are exceptions, not the rule.

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