Chapter 2 System Overview
Compaq Deskpro 4000 and 6000 Personal Computers
featuring the Pentium II Processor
First Edition - October 1997
2-8
2.4 SYSTEM ARCHITECTURE
Figure 2-7 shows the architecture of the Compaq Deskpro 4000 and 6000 Series Personal
Computers based on the Pentium II processor and matched with a support chipset that is
complimentary in design. Both minitower and desktop systems share the same basic architecture,
which utilizes three main buses: the Host bus, the Peripheral Component Interconnect (PCI) bus,
and the Industry Standard Architecture (ISA) bus.
The Host bus provides high performance support for CPU, cache and system memory accesses,
and operates at 66 MHz. The PCI bus provides support for the graphics subsystem, the EIDE
controllers, and expansion devices designed for high performance. The PCI bus operates at 33
MHz. The ISA bus provides a standard 8-MHz interface for the input/output (I/O) devices such
as the keyboard, diskette drive, serial and parallel interfaces, as well as the addition of 16- or 8-
bit expansion devices.
These systems also include Accelerated Graphics Port (AGP) support. The AGP interface
provides a 66-MHz synchronous coupling with the Host bus for AGP-type graphics adapters.
The Deskpro 6000 models come standard with a Matrox Millennium-II AGP graphics board
installed.
The Host/PCI and PCI/ISA bridge functions are handled by the specific support chipset matched
with the microprocessor employed. The support chipset also provides memory controller and data
buffering functions as well as bus control and arbitration functions.
The I/O port functions and diskette drive controller are integrated into the National PC87307 I/O
Controller. This component also includes the real time clock and battery-backed configuration
memory (CMOS).
Table 2-1 lists the key differences between the Dekspro 4000 and 6000 systems.
Table 2–1.
Architectural Comparison
Table 2-1
.
Architectural Comparison
Deskpro 4000 Deskpro 6000
CD-ROM Type (if installed) 24x CD-ROM (IDE) 24x CD-ROM (IDE)
System Memory
Standard installed:
Expandable to:
32 MB
384 MB
32/64 MB
384 MB
Active Hard Drive Interface: EIDE SCSI
Graphics Subsystem: Matrox MGA-1064SG-based
PCI Card
w/2 MB SGRAM
Matrox Millennium-II
AGP Card
w/4 MB WRAM
The following subsections provide a description of the key functions and subsystems.
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