Dram Interface Support; I/O Support; Pxb Features - Intel 460GX Software Developer’s Manual

Introduction
1.4

DRAM Interface Support

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SDRAM 3.3 volt, 168-pin DIMM's are the only memory type supported.
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Support for 64 MB to 64 GB of DRAM.
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Minimum memory size is 64 MB using 16 MB DIMM's.
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Minimum incremental size is 64 MB using 16 MB DIMM's.
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Maximum memory size is 16 GB using 128 MB DIMM's.
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Maximum memory size is 64 GB using 1 GB DIMM's.
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Only 3.3 volt memory is supported.
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Support for Auto Detection of SDRAM Memory Type.
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Supports 16, 64, 128 and 256 Mbit DRAM devices.
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Mixed memory sizes allowed between rows.
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Staggered CAS-before-RAS refresh (standard SDRAM refresh).
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ECC with single-bit error correction, double and nibble error detection.
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Extensive processor-to-Memory and PCI-to-Memory write data buffering, thus minimizing
the interference of writes on read latency.
1.5

I/O Support

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4 Expander ports, each 30 bits wide and providing 533 MB/s peak bandwidth.
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Each Expander bus supports a single PXB or WXB. Two Expander busses can be configured
to support a GXB.
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Full support for the PCI Configuration Space Enable (CSE) protocol to devices on all
Expander ports.
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Data streaming support between Expanders and DRAM, up to 533 MB/s per Expander port.
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All outbound memory and I/O reads (except locked reads) are deferred.
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All outbound memory space writes are posted. Outbound I/O space writes are optionally
posted (unless targeting an address with side effects, in which case they are deferred).
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All inbound memory reads are delayed.
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All inbound memory space writes are posted.
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Supports concurrent processor and I/O initiated transactions to main memory.
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Maintains coherency with processors by snooping all inbound transactions to the system bus.
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Supports non-coherent traffic (for AGP), with a direct path to memory bypassing the system
bus.
1.5.1

PXB Features

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Can be configured to provide two independent 32 bit, 33 MHz PCI buses or one 64 bit, 33
MHz PCI bus.
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PCI Rev. 2.2, 5V tolerant (PXB drives 3.3 volts, but is 5.0 volt tolerant).
1-4 Intel® 460GX Chipset Software Developer's Manual