Dell Vostro 400, Service Manual, Page: 13 / 118

System Overview 1-1
Chapter 1
System Overview
T
he Dell
®
WorkStation 400 systems are high-speed, upgradable computers.
They are available in two sizes: a midsize desktop computer and a mini tower
computer. Chapters 1 through 3 and Appendix A contain information that
applies to all models of the Dell WorkStation 400 systems. Chapters 4 and 5 are
chassis-specific.
The Dell WorkStation 400 systems use the Intel
®
Pentium
®
II family of micro-
processors. A single-edge contact (SEC) cartridge connected to the system
board contains the system’s microprocessor and cache circuitry. These Dell
computers incorporate the high-performance PCI local bus as well as the ISA
expansion bus. These buses are built into the system board, which also inte-
grates the processor, optional second processor, memory controller, hard-disk
drive controller, and other elements of the basic computer.
The Pentium II microprocessor contains a built-in clock multiplier circuit,
which increases the microprocessor’s internal operating frequency to a multiple
of the system clock frequency. The microprocessors for Dell WorkStation 400
systems operate at a frequency of either 266 MHz or 300 MHz, derived from a
system clock frequency of 66 MHz.