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System Components and Features
1.1.3 L3 Bcache Subsystem Overview
The AlphaPC 164LX board-level L3 backup cache (Bcache) is a 2MB, direct-
mapped, synchronous SRAM with a 128-bit data path. The board is capable of han-
dling an L3 cache size of 4MB. See Section 2.3 for more information about the
Bcache.
1.1.4 PCI Interface Overview
The AlphaPC 164LX PCI interface is the main I/O bus for the majority of functions
(SCSI interface, graphics accelerator, and so on). The PCI interface has a 33-MHz
data transfer rate. PCI-IDE support is provided by an onboard controller chip
(CMD646). An onboard PCI-to-ISA bridge is provided through an Intel 82378ZB
Saturn-I/O (SIO) chip.
The PCI bus has four dedicated PCI expansion slots (two 64-bit and two 32-bit).
1.1.5 ISA Interface Overview
The ISA bus provides the following system support functions:
•
Two expansion slots.
•
An SMC FDC37C935 combination controller chip that provides:
–
A mouse and keyboard controller
–
A diskette controller
–
Two universal asynchronous receiver-transmitters (UARTs) with full
modem control
–
A bidirectional parallel port
–
A time-of-year (TOY) clock
•
Operating system support—through a 1MB flash ROM that contains supporting
firmware.
1.1.6 Miscellaneous Logic
The AlphaPC 164LX contains the following miscellaneous components:
•
Synthesizer for clocks:
–
A clock synthesizer (MC12439) provides a programmable 466-, 533-, and
600-MHz clock source to the 21164 microprocessor. The microprocessor
supplies a clock to the system PLL/clock buffer for the 21174.
Introduction
1–4
22 January 1998 – Subject To Change
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