KC82870DH S L5X2 Intel, KC82870DH S L5X2 Datasheet - Page 35

• Manufacturer Part Number: KC82870DH S L5X2
• Manufacturer: Intel

Specifications of KC82870DH S L5X2

• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Not Compliant

4.6.2
4.7
4.8
4.8.1
Intel
®
E8870DH DDR Memory Hub (DMH) Datasheet
16-Byte Mode
In this mode, each DDR SDRAM is programmed to use a burst length of 16 bytes (two transfers)
across the Branch Channel. Each DIMM’s Mode Register must be programmed for a burst length
of 2 and for sequential mode.(as defined in the Jedec Standard JESD79) In addition, the DMH
MCTIM register DTS field must be set to a 16-byte mode. The DMH sends and receives data
across the Main Channel in bursts of 8 transfers at 2 bytes/transfer.
Write Buffers
The DMH uses write buffers to decouple the Main Channel’s Write Data timing from the Branch
Channel Write Data timing. Without the write buffer mechanism, write-command to write-data
timing would require a longer time period than read-command to read-data timing, resulting in a
large turnaround time.
The DMH implements write buffering with FIFOs. The DMH maintains three independent write
FIFOs for Activate for Write MCPs, Write Command MCPs, and Write Data. Read-hit logic
ensures that the most recently written data is always returned on a read.
The timing between the Write Command MCP and its data phase on the Main Channel should be
set (see
relationship as the Read Command MCP and its data phase on the Main Channel.
During PWRGOOD deassertion, or RESET# assertion, the state of all FIFO entries are
asynchronously set to invalid. The DMH does not generate a Branch Channel transaction from an
invalid entry popped off of a FIFO. The FIFO is 4-deep for 32-byte mode and 8-deep for 16-byte
mode.
Write transactions to both Branch Channels are staged through a single set of FIFOs (Activate
command, Write command, and Write data).
Memory Translation Rules
Read Rules
The following read rules apply:
1. Open-Page Activate for Read command must be issued to open a page before reads to the page
2. Multiple pages may be open for reading at the same time.
3. An Activate for Read cannot be issued to a page that is currently opened due to an Activate for
are allowed.
Write.
Section 3.3, “MCTIM – Main Channel Timing
Register”) such that it has the same
Functional Description
4-7