Dell Dimension XPS R Series, Service Manual

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System Overview 1-1
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The Dell Dimension
®
XPS R xxx systems are high-speed computer systems
that use an Intel
®
Pentium
®
II microprocessor with MMX
™
technology. These
Dell
®
systems combine Peripheral Component Interconnect (PCI) design with
an accelerated graphics port (AGP) and Industry Standard Architecture (ISA)
design that allows a wide range of initial configurations and upgrade
possibilities.
The Dell Dimension XPS Rxxx systems are available in either a desktop or a
mini tower configuration. Both configurations use the same system board and
base chassis. The only difference, other than physical mounting, is the number
of externally accessible 3.5-inch drive bays.
The front of the computer has two 5.25-inch drive bays and one 3.5-inch
diskette-drive bay. In addition, the mini tower systems have two 3.5-inch drive
bays and the desktop system has one 3.5-inch drive bay. The 5.25- and 3.5-inch
drive bays can hold diskette drives, tape drives, or CD-ROM drives.
The Pentium II microprocessor contains a built-in clock multiplier circuit that
increases the internal operating frequency to a multiple of the system clock
frequency, which is 100 MHz.
The microprocessors for each of these computers and their operating frequen-
cies are as follows:
‡
Dell Dimension XPS R350 systems — 350-MHz Pentium II microprocessor
with MMX technology
‡
Dell Dimension XPS R400 systems — 400-MHz Pentium II microprocessor
with MMX technology
A single-edge contact (SEC) cartridge connected to the system board contains
the system’s microprocessor and cache circuitry.
Main memory consists of up to three DIMMs. The base configuration for main
memory is one 64-MB DIMM. Main memory can be expanded up to 384 MB
by using 32-, 64-, or 128-MB DIMMs.