Q. What is Fully Buffered DIMM?

A.FB-DIMM is a new memory interconnect technology standard for high-end memory connections. FB-DIMM transitions the memory channel to a serial interface and replaces the DIMM register with a memory buffer. FB-DIMM connections are expected to enable systems to scale the number of memory channels available to a server system. Implementations of FB-DIMM enabled DDR2 memory are expected in future Intel architecture-based platforms.

Current DIMMs will be unable to handle the memory requirements of the type of high-speed servers that will use DDR2 at speeds of 667 to 800 Mbits/s. PCs, which don't have the very large memory size of most servers, can use the standard DDR2 without the buffer. A conventional buffered DIMM includes added logic that reduces the loading on the system address and control bus lines. A system designed for buffered DIMMs can use more modules, since the buffer chips absorb some of the load.

A new Memory Implementers Forum (www.memforum.org) has been formed to focus on developing memory technologies including DDR2 and Fully Buffered-DIMM (FB-DIMM).

Q. Which DIMM's do your FS2338 and FS2343 Analysis Probes support?

A. DIMMs that meet JEDEC spec MO-224.

Q. Which is the difference between the FS2338 and the FS2343?

A. The use model for both of these probes is similar, meaning they are designed to analyze the High Speed Channel traffic between the memory controller and the AMB. The FS2338 "consumes" a DIMM slot when it is used. Because the FS2343 has an interposer connector on it, it does not consume a slot. However, since the DIMM in the interposer connector sticks up vertically, it may cause vertical interference problems. Also, the FS2343 presents an additional load on the memory bus because it has the load of the DIMM and the load of the circuitry on the FS2343. If the vertical clearance issue is not a problem for you, we recommend you try the FS2343. If the additional electrical loading causes problems, you can substitute the FS2338 and you should be successful.

Q. Why can the FS2338 operate at up to 4.8 Gb/s, but the FS2343 is limited to 4.0?

A.The FS2343 has an interposer function incorporated into it. This allows a DIMM to be installed in the interposer socket. The AMB chip on the DIMM requires power from the FS2343. At speeds above 4.0 Gb/s the AMB chip draws too much power for the FS2343 to supply. The FS2338 operates at the full 4.8 Gb/s speed.

Q. Why do your FS2338 and FS2343 require five logic analyzer cards when they only requires five termination adapters?

A. The logic analyzer cards are being used in dual sample mode; each card has only two pods available in this mode. There are signal connections on the FS2338 and FS2343 for up to six different logic analyzer termination adapter cables. This allows you to determine which signals you wish to monitor, e.g. SB or NB only, all trigger events, SB and NB traffic together, etc. Depending on which signals you monitor, you will need from three to five cards. See the System Requirements page for details.

Q. Why can't I use the 16700 / 702 logic analyzer systems with the FS2338 and FS2343?

A. Good question. The 16900/902 frames are the only ones supported because the FB DIMM probes require logic analyzer control via the I2C and ProbeAddin interfaces on the 16900/902.

Q. Can you guarantee the FS2338 or FS2343 will operate correctly in my system?

A. Another good question. Factors beyond the control of FuturePlus Systems that can have a significant effect on the performance of the whole system include the type of memory controller and AMB, the target layout, the type of DIMM used, which DIMM socket is being probed, and which logic analyzer cards are being used. So, we cannot guarantee your success. We have made every effort to give you products that have every chance of succeeding. Since the FS2338 presents less of an electrical load, it has the best chance of success. It does consume a slot, however.

Q. Can the FS2338 or FS2343 perform Eye Scan measurements?

A. Eyescan will not be a useful tool on the FS2338 or FS2343 because the logic analyzer connection is downstream from the AMB chip on the analysis probe.

Q. What software is included with the FS2338 or FS2343 FBD Analysis Probe?

A. Files are included that automatically set up the Agilent logic analyzer for state or timing analysis mode and label all the signal names. An protocol decoder is included to translate the data on the High Speed Channel into memory protocol trancactions during state analysis.

Q. Does your probe get its power from my system?

A. The FS2338 has some circuitry that draws power from your system. The FS2343 also draws some power from your system. In addition, an external supply is provided to supply power to the additional DIMM installed in the interposer connector.

Q. I'm having a little problem. The probe control for my FBDIMM slot and interposer probes will not communicate with the LAI through the logic analyzer SMBus. My cables are attached properly and the external power supply is plugged in, but the probe control will only load in the offline mode. What's the problem?

A. Your FBDIMM probes are going offline because of the logic analyzer firmware needing an upgrade. Contact our Technical Support and they will send you a file and instructions for the update.

Q. How do I find out what are the latest versions of Agilent logic analyzer operating software?

A. Contact your nearest Agilent Call Center.

Q. How do I know which Agilent logic analyzer is best for my needs?

A. Click here.

Have a question you don't see answered? Contact Technical Support for a prompt answer.