System Board; Processor; System Memory; Cache Memory - Compaq DESKPRO 2000 SERIES Maintenance & Service Manual

1.3.2 System Board

The desktop and minitower models of the Compaq Deskpro 2000 Series of Personal Computers use two
basic system board configurations, either a Pentium- or a Pentium Pro–based board. The desktop units
have the I/O panel mounted to the system board and are spared with the I/O panel attached. On the
minitower, the system board is attached to a sliding tray and is spared with the tray.

1.3.3 Processor

The Pentium-based system boards run at processor speeds of 100MHz to 200MHz.
The Pentium Pro-based system boards run at processor speeds of 180MHz and 200MHz.

1.3.4 System Memory

The system supports base (conventional) and extended memory. Operating systems such as MS-DOS,
OS/2, UNIX, and all application programs use base memory. For better performance, Windows NT,
OS/2, and UNIX, as well as many MS-DOS applications, use extended memory.
The computers ship standard with 60-ns EDO tin-lead (SnPb) SIMMs installed and supports up to 128
megabytes of memory (Pentium models) or 192 megabytes of memory (Pentium Pro models). Either
Extended Data Out (EDO) random access memory (RAM) or Fast Page Mode (FPM) dynamic random
access memory (DRAM) modules may be used. If EDO and FPM modules are combined in the
computer, they must be as matched pairs. For example, two identical EDO modules may be used with
two identical FPM modules.
The SIMM sockets on all system boards in this series of computers can be populated with 4-, 8-, 16-, or
32-MB SIMMs in matched pairs. SIMM sockets on the system boards must be populated in pairs of
equal size in sequential slots. The SIMMs for the system boards must be 60 ns or 70 ns. Refer to
Chapter 5, "Removal and Replacement Procedures," for information on how to upgrade system
memory.
The Pentium-based system boards accommodate a total of four SIMMs.
The Pentium Pro-based system boards accommodate a total of six SIMMs.
SIMMs with tin-lead pins must be used for memory upgrades.
System memory speed will be configured on a bank-by-bank basis allowing each bank to run at its
optimum speed.

1.3.5 Cache Memory

Cache memory is very fast memory used for temporarily storing data for fast access by the processor.
The faster the processor, the more need there is for temporary data storage. One 256-kilobyte write-
back, direct mapped secondary (L2) cache module is installed on the Pentium system board. Cache is
standard on models with a speed of 120 megahertz or higher. Cache is optional on lower speed
processors. A 256-kilobyte write-back, four-way, set associative secondary (L2) cache is integrated into
the processor on Pentium Pro models.
Compaq Deskpro 2000 1-7