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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors—Memory Controller
Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
Developer’s Manual
August 2006
596
Order Number: 306262-004US
If the current transaction hits the open page, then the page is already active and the
read
or
write
command may be issued without a
row-activate
command. When the next
transaction is the same command type as the current transaction, and also a page hit,
the MCU does not need to issue the command again, but simply drive column address
for an open page.
If the refresh timer expires and the MCU issues an
auto-refresh
command, all pages are
closed.
illustrates the performance benefit of a read hit versus a read miss in
illustrates the performance benefit of a write hit versus a write
Figure 104. Page Hit/Miss Logic for 128/256/512/1, 024-Bit Mode
B4209-001
Bank 0
Leaf 0
Bank 0
Leaf 1
Bank 0
Leaf 2
Bank 0
Leaf 3
Bank 1
Leaf 0
Bank 1
Leaf 1
PageComparator
En
a
b
le
Bank 1
Leaf 2
Bank 1
Leaf 3
Valid
Valid
Valid
Valid
Valid
Valid
Valid
Valid
Open Page Address 0
Open Page Address 1
Open Page Address 2
Open Page Address 3
Open Page Address 4
Open Page Address 5
Open Page Address 6
Open Page Address 7
Pag e Reg ist erSelect
PageHit
D
DRI
_
B
A[
1
:0
]
DDR
I_
CS
_
N
[1
:0
]
A
D
D
R
[31:
12
]
Pag e Reg ist er