System Board; Principal Components And Features - HP Vectra XM5 4 Technical Reference Manual

2 SYSTEM BOARD

The next chapter describes the video, disk and network devices which are supplied with the
PC.
This chapter describes the components of the system board.

PRINCIPAL COMPONENTS AND FEATURES

The system board, as depicted on the next page, contains the following components:
Processor Socket
The microprocessor is packaged in a pin-grid-array (PGA), which is seated on the system board
in a zero-insertion-force (ZIF) socket .
VRM Socket
P54C (75, 90 and 100 MHz) Pentium processors, and P54CS (133 and 150 MHz) Pentium
processors require a 3.3 V supply. Since the power supply of the PC has a regulated 3.3 V
output, a shorting block is used to connect this directly to the Pentium processor.
P54C (120 and 166 MHz) Pentium processors require slightly more than 3.3 V, and therefore
need an active VRE voltage regulator module (VRM), in which the voltage is derived both from
the 3.3 V and 5 V outlets of the power supply.
System Board Switches
The functions of the system board switches , used for configuring the PC, are summarized in
the following table:
Switch
-
1-4
5 Open
Closed
6 Open
Closed
-
7
8 Open
Closed
9 Open
Closed
10 Open
Function
Processor frequency, see the table under "Bus Frequencies"
later in this chapter
Enables User and Administrator passwords
Clears User and Administrator passwords
CMOS memory acts as non-volatile store for the Setup
data
Clears the Setup configuration data in the CMOS memory
Processor frequency, see the table under "Bus Frequencies"
later in this chapter
Disables secure mode
Enables secure mode - prevents modification of the Setup
data and flashing of the BIOS
Disables keyboard power-on
Enables keyboard power-on
Not used
Default
-
Open
Open
-
Open
Closed
Open