Logic Analyzer Interface (Lai); Mechanical Considerations; Electrical Considerations - Intel 855GM Design Manual

Intel Pentium M/Celeron M Front Side Bus Design Guidelines
not required and can be left as no connect. However, it is the responsibility of the system designer to
determine whether termination for DBA# is required or not.
4.3.3.

Logic Analyzer Interface (LAI)

Intel is working with Agilent Corporation to provide logic analyzer interfaces (LAIs) for use in
debugging Intel Pentium M processor / Intel Celeron M processor based systems. LA vendors should be
contacted to get specific information about their logic analyzer interfaces. The following information is
general and specific information must be obtained from the logic analyzer vendor.
Due to the complexity of a processor based system, the LAI is critical in providing the ability to probe
and capture the Processor System Bus signals. There are two sets of considerations to keep in mind
when designing a processor based system that can make use of an LAI: mechanical and electrical.
4.3.3.1.

Mechanical Considerations

The LAI is installed between the processor socket and the processor. The LAI pins plug into the socket,
while the Intel Pentium M processor / Intel Celeron M processor in the 478-pin package plugs into a
socket on the LAI. Cabling this part of the LAI egresses the system to allow an electrical connection
between the processor and a logic analyzer. The maximum volume occupied by the LAI, known as the
keep-out volume, as well as the cable egress restrictions, should be obtained from the logic analyzer
vendor. System designers must make sure that the keepout volume remains unobstructed inside the
system. Note that it is possible that the keepout volume reserved for the LAI may include space
normally occupied by the processor heat sink. If this is the case, the logic analyzer vendor will provide a
cooling solution as part of the LAI.
4.3.3.2.

Electrical Considerations

The LAI will also affect the electrical performance of the Intel Pentium M Processor / Intel Celeron M
processor FSB. Therefore, it is critical to obtain electrical load models from each of the logic analyzers
to be able to run system level simulations to prove that their tool will work in the system. Contact the
logic analyzer vendor for electrical specifications as load models for the LAI solution they provide.
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Intel 855GM/855GME Chipset Platform Design Guide
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