Alphapc 164Lx Sdram Memory Configurations; Digital Semiconductor 21174 Core Logic Chip; Memory Subsystem - DEC AlphaPC 164LX Technical Reference Manual

1.1.1 DIGITAL Semiconductor 21174 Core Logic Chip

The Alpha 21164 microprocessor is supported by the 21174 core logic chip, which
provides an interface between three units—memory, the PCI bus, and the 21164
(along with flash ROM). This core logic chip is the interface between the 21164
microprocessor, main memory (addressing and control), and the PCI bus.
Sixteen quick switches provide the memory interface data path.
The 21174 includes the majority of functions necessary to develop a high-perfor-
mance PC or workstation, requiring minimum discrete logic on the module. It pro-
vides flexible and generic functions to allow its use in a wide range of systems.

1.1.2 Memory Subsystem

The synchronous dynamic random-access memory (SDRAM) is contained in two
banks of dual inline memory modules (DIMMs). Single- or double-sided DIMMs
may be used. Each DIMM is 72 bits wide, with 64 data bits and 8 check bits, with
100 MHz or faster speed. Two DIMMs provide 32Mb to 256MB of memory, while
four DIMMs provide up to 512MB. Table 1–1 lists the DIMM sizes tested and the
corresponding main memory size for 128-bit arrays.
Table 1–1 AlphaPC 164LX SDRAM Memory Configurations
Total
Memory
32MB
64MB
96MB
128MB
160MB
192MB
256MB
512MB
22 January 1998 – Subject To Change
System Components and Features
Bank 0 (J8 and J9)
2Mb 72
X
2Mb 72
X
4Mb 72
X
4Mb 72
X
4Mb 72
X
8Mb 72
X
8Mb 72
X
8Mb 72
X
8Mb 72
X
16Mb 72
X
16Mb 72
X
Bank 1 (J10 and J11)
—
2Mb 72
X
—
2Mb 72
X
4Mb 72
X
—
2Mb 72
X
4Mb 72
X
8Mb 72
X
—
16Mb 72
X
Introduction
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