Intel
®
81341 and 81342—DDR SDRAM Memory Controller
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
592
Order Number: 315037-002US
illustrates how the logical memory image is partitioned with respect to open
and closed pages. When the above image represents a 128 Mbyte DDR SDRAM
memory size, each bank is 64 Mbytes and each leaf is 16 Mbytes.
Only one page may be open within each of the leaf blocks. The block sizes depend on
the memory sizes implemented in the DDR SDRAM memory subsystem. The page size
is always 8 Kbytes for a 64-bit wide memory data bus, and 4 Kbytes for a 32-bit wide
memory data bus. The programmer can optimize DDR SDRAM transactions by
partitioning code and data across the leaf boundaries to maximize the number of page
hits.
Figure 85. Logical Memory Image of a DDR SDRAM Memory Subsystem
Page 2
Bank 0 Leaf 0
Page 3
Bank 0 Leaf 1
Page 0
Bank 0 Leaf 2
Page 1
Bank 0 Leaf 3
Page 2
Bank 0 Leaf 4
Page 2
Bank 0 Leaf 5
Page 0
Bank 0 Leaf 6
Page 1
Bank 0 Leaf 7
Page 2
Bank 1 Leaf 0
Page 3
Bank 1 Leaf 1
Page 0
Bank 1 Leaf 2
Page 2
Bank 1 Leaf 3
Page 1
Bank 1 Leaf 4
Page 3
Bank 1 Leaf 5
Page 0
Bank 1 Leaf 6
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Bank 1 Leaf 7
Page 0 (closed )
Page 1 (closed)
Page 2 (OPEN)
Page 3 (closed)
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Page 0 (closed)
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Page 0 (OPEN)
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Page 0 (closed)
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Page 0 (closed)
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Page 0 (closed)
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Leaf 0
Bank 0
Leaf 1
Leaf 2
Leaf 3
Leaf 4
Leaf 5
Leaf 6
Leaf 7
Page 0 (closed)
Page 1 (closed)
Page 2 (OPEN)
Page 3 (closed )
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Page 0 (closed)
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Page 0 (closed)
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Page 0 (OPEN)
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Page 0 (closed)
Page 1 (closed)
Page 2 (OPEN)
Page 3 (closed)
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Leaf 0
Bank 1
Leaf 1
Leaf 2
Leaf 3
Leaf 4
Leaf 5
Leaf 6
Leaf 7
B6259-01