Compaq 4000N Manual De Usuario
Chapter 3 Processor/Memory Subsystem
Compaq Deskpro 4000N and 4000S Personal Computers
First Edition - September 1997
3-2
Mem.
Data Bus
Data Bus
Mem. Addr.
3.2
PENTIUM MMX-BASED PROCESSOR/MEMORY SUBSYSTEM
The processor/memory subsystem is based on the Pentium MMX microprocessor, a 512-KB or 1-
MB secondary cache, and a VT82C595 system controller (Figure 3-1).
MB secondary cache, and a VT82C595 system controller (Figure 3-1).
Figure 3–1. Processor/Memory Subsystem Architecture
The microprocessor is mounted in a ZIF type 7 socket that facilitates easy changing/upgrading.
The system supports both 2.8V and 3.3V core processors. Replacing the microprocessor may
require reconfiguring a DIP switch to select the correct bus frequency/core frequency
combination. Frequency selection is described in detail later in this section.
The system supports both 2.8V and 3.3V core processors. Replacing the microprocessor may
require reconfiguring a DIP switch to select the correct bus frequency/core frequency
combination. Frequency selection is described in detail later in this section.
The VT82C595 system controller provides the Host/PCI bridge functions and controls transfers
with the 64-bit memory data bus. The system includes 256 kilobytes of SRAM controlled by the
system controller as a direct-mapped, write-through L2 cache to the L1 cache integrated into the
microprocessor. The system supports synchronous, pipelined burst SRAM/DRAM for the L2
cache, providing 3-1-1-1 read/write cycles at 60 and 66 MHz on a cache hit.
with the 64-bit memory data bus. The system includes 256 kilobytes of SRAM controlled by the
system controller as a direct-mapped, write-through L2 cache to the L1 cache integrated into the
microprocessor. The system supports synchronous, pipelined burst SRAM/DRAM for the L2
cache, providing 3-1-1-1 read/write cycles at 60 and 66 MHz on a cache hit.
The standard system memory configuration consists of 16 or 32 megabytes of SDRAM system
memory. The system memory can be expanded to 256 megabytes.
memory. The system memory can be expanded to 256 megabytes.
Pentium MMX
Microprocessor
32-bit PCI Bus
256-KB
Secondary
Cache
Optional module
16-MB
DIMM
J7
J8
System Memory
64-Bit Host Bus
Cache/
Memory/PCI
Controller
(VT82C595)
Cntl
Cntl
Memory/PCI
Data Buffer
()
DIMM