82443GX Datasheet, PDF (97/128 Pages) Intel Corporation – Intel 440GX AGPset: 82443GX Host Bridge/Controller

Functional Description
4.3.2
DRAM Address Translation and Decoding
The 82443GX supports 16, 64, 128, and 256 Mbit¹ DRAM devices. The 82443GX supports 2 KB,
4 KB and 8 KB page sizes. Page size varies per row depending on how many column address lines
are used for a given row. Rows containing SDRAMs with 8 column address lines have a 2 KB page
size. Those with 9 column address lines have a 4 KB page size and those with 10 column address
lines have an 8 KB page size. The 82443GX supports 11 column address line devices but the page
size is limited to 8 KB. The multiplexed row/column address to the DRAM memory array is
provided by the MA[14:0] signals.
Row and Column address multiplexing on the MA[14:0] lines is determined on a row by row basis
allowing for three possible page sizes. SDRAMs have either 8, 9 or 10 column lines allowing for
2 KB, 4 KB or 8 KB page sizes. The page size is determined primarily by the row size and type
(SDRAM).
Either 2 or 4 pages can be open at any time within any row. If a row contains SDRAMs based on
16Mb technology (i.e., 12x8/9/10 devices) then two pages can be open at a time within that row. If
a row contains SDRAMs based on 64Mb, 128Mb, or 256Mb¹ technology, then four pages can be
open at a time within that row.
This address multiplexing scheme is derived from Table 4-10 which depicts the addressing
requirements for each of the row/column organizations for each row size. The SDRAM
components used for the options shown in the table are as follows:
Option
1 (16 MB)
2 (32 MB)
3 (64 MB)
4 (128 MB)
5 (256 MB)
6 (512 MB)
SDRAM Component Type
2Mx8
4Mx16 or 4Mx4
8Mx8
16Mx16 or 16Mx4
32Mx4, 32Mx8
64Mx4
Note: 4Mx4, 16Mx4, 32Mx4, and 64Mx4 SDRAM devices are supported in the form of Registered
DIMMs only.
1. Proper operation of the 82443GX AGPset with 256-Mbit SDRAM devices has not yet been verified. Intel’s current plans are to validate this feature
in the second half of 1998 when 256-Mbit SDRAM devices are available.
82443GX Host Bridge Datasheet
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