Intel
®
81341 and 81342—DDR SDRAM Memory Controller
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
564
Order Number: 315037-002US
7.2
Glossary
This section lists commonly used terms throughout this chapter:
Table 344. Commonly Used Terms
Term
Definition
Bank
A bank is defined as a memory region defined with a base register and a bank size register.
Physically, a bank of memory is controlled by a single chip select. A DIMM comprised of a
single or dual banks.
Column
A column refers to a portion of memory within a DDR SDRAM device. A DDR SDRAM device is
thought of as a grid with rows and columns. Once a row is activated, any column within that
row is accessed multiple times without reactivating the row. Columns are activated with
CAS#
.
DIMM
A DIMM is an acronym for Dual Inline Memory Module. A DIMM is a physical card comprising
multiple DDR SDRAM devices. The card is populated on one or both sides. A DIMM is single or
dual-bank.
Leaf
DDR SDRAM devices use multiple banks within the device operating in an interleaved mode.
The DMCU supports 512 Mbit and 1 Gbit and 2 Gbit DDR-II SDRAM devices. 512 Mbit DDR-2
SDRAM devices support four internal banks, whereas 1 Gbit and 2 Gbit DDR-2 SDRAM devices
support eight internal banks. An internal bank is defined as a leaf (to avoid confusion with a
memory bank).
Page
A page is a row of memory. Once a row is activated, any column within that row can be
accessed multiple times without reactivating the row. This is referred to as “keeping the page
open.”
Row
A row refers to a portion of memory within a DDR SDRAM device. A DDR SDRAM device is
thought of as a grid with rows and columns. Once a row is activated, any column within that
row isaccessed multiple times without reactivating the row. Rows are activated with
RAS#
.
Scrubbing
Once an error is detected within the memory array, the DMCU must correct the error (when
possible) while delivering the data to the initiator. Correcting the memory location is referred
to as “scrubbing the array.” The DMCU relies on software to scrub any errors.
Syndrome
A syndrome is a value which indicates an error in the data read from the memory array. The
DMCU computes the syndrome with every memory read. Decoding the syndrome indicates:
the bit in error for a single-bit error, or a multi-bit error.
defines the syndrome
decoding.