HP KAYAK XU800 Dual Rambus Bus, The Dual Rambus bus is comprised of 16 x 2 bits of data information, and

2 System Board

Memory Controller Hub (8240)

The following table shows the number of Rambus devices and memory technology available on a memory module.

	Memory Technology (number of Megabits)
Number of devices	64 Mbits	128 Mbits	256 Mbits
per RIMM
4	N/A	64 MB module	128 MB module
8	N/A	128 MB module	256 MB module
16	128 MB module	256 MB module	512 MB module

MCH also provides optional data integrity features including ECC in the memory array. During DRAM writes, ECC is generated on a QWord (64 bit) basis. During DRAM reads, the MCH supports multiple-bit error detection and single-bit error correction when the ECC mode is enabled.

MCH will scrub single bit errors by writing the corrected value back into DRAM for all reads when hardware scrubbing is enabled. This, however does not include reads launched in order to satisfy an AGP transaction.

Dual Rambus BusThe Dual Rambus bus is comprised of 16 x 2 bits of data information, and

8 bits of Error Correcting Code (ECC). The bus is connected to the Memory Expansion Card Connector and to the MCH chip supporting two Dual Rambus channels (A and B).

Both channels run at 300 or 400 MHz supporting up to 32 rambus devices per channel (individual chips) or one MRH-S (Memory Repeater Hub) per channel for DIMM sockets. The maximum available data bandwidth is 3.2 GB/s at 400 MHz.

The configuration of both primary rambus channels must be symmetrical. That is to say, whatever the configuration on channel A, the same must be on channel B.

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