AMD-751 Datasheet, PDF (12/14 Pages) Advanced Micro Devices – AMD-751-TM System Controller Revision Guide

Preliminary Information
AMD-751™ System Controller Revision Guide
22564B-1—February 2000
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Potential Memory Failure When Using Certain Double-Sided SDRAM
Memory DIMMs
Products Affected. C3 and C5
Description. Under certain SDRAM double-sided DIMM loading conditions, systems based on the the
AMD-751 system controller can experience reduced timing margins, resulting in memory failures
during memory cycles.
This condition only occurs when using specific double-sided DIMMs with combinations of the following
characteristics:
1. Printed Wiring Board (PWB) designed around the Intel LC_12_112 Gerber.
2. Memory ICs with lower V_IL input thresholds.
Potential Effect on System. Unstable system.
Suggested Workarounds.
1. Vendors should use memory DIMMs only from an approved vendor list (AVL). DIMMs
from this list have been extensively tested on AMD-751 based platforms and qualified for
usage. Please consult your OEM or AMD specialist for details.
2. Vendors developing new AMD-751 based motherboards should implement pulldown
resistors on the MAA[14:0] and MAB[14:0] address buses. Use of this termination
method will improve the timing margins. Please consult your OEM or AMD specialist for
specific values.
Resolution Status. All future motherboards should be implemented with the suggested termination
method.
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