FBD Channel Interface
2.6
Repeater Mode
The AMB may also be used as an FBD link repeater to extend distances at which links
can operate. This mode can be automatically set by the BFUNC and SA pins. In this
mode, the AMB functions in the same way as a regular DIMM with the exception that
DRAM commands are not supported.
Link behavior is the same as for normal DIMMs
• Participates in link initialization like a normal DIMM
• Responds to Reads and Writes to AMB configuration registers
• Status is returned in response to Sync commands
• Link errors are detected and alerts generated
SMBus access is the same except for the base Slave address is different than from
normal DIMM.
Slave address[6:3] = 4’b0011 for Repeaters, instead of
Slave address[6:3] == 4’b1011 for normal DIMMs
2.7
Channel Latency
The critical elements that AMB contributes to the latency calculation are the chip
crossing delays.
• Southbound latency contributions
— Delay from an input FBD link transaction to commands on the DDR interface
and
— Pass-thru delay of forwarded Southbound FBD transactions.
• Northbound latency contributions
— Delay from DDR Read data input on the last DIMM to FBD link transactions and
— Pass-thru delay of forwarded Northbound FBD transactions back towards the
host.
These timing delay values are documented in Chapter 4, “Electrical, Power, and
Thermal.”
2.7.1
Command to Data Delay Calculation
shows the various components that make up the over all delay through an AMB for a
memory command.
Intel® 6400/6402 Advanced Memory Buffer Datasheet
21
INTEL [ INTEL ]
