Dell Precision 420 User Manual page 67

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Hardware Configuration Features: Dell Precision™ WorkStation 420 Systems User's
Guide
Overview
Jumpers
System Board Labels
Overview
This section provides specific information about the jumpers on your system board and the input/output (I/O) ports and connectors on the back
panel of your computer. It also provides some basic information on jumpers, a listing of interrupt request (IRQ) assignments, and memory maps.
Jumpers
Jumpers provide a convenient and reversible way of reconfiguring the circuitry on a printed circuit board. When you reconfigure your system, you
may need to change jumper settings on your system board; you may also need to change jumper settings on expansion cards or drives.
Jumpers are small blocks on a circuit board with two or more pins emerging from them (see Figure 1). Plastic plugs containing a wire fit down over
the pins. The wire connects the pins and creates a circuit.
Figure 1. Jumpers
To change a jumper setting, pull the plug off its pin(s) and carefully fit it down onto the pin(s) indicated.
NOTICE: Make sure that your system is turned off before you change a jumper setting. Otherwise, damage to your system or
unpredictable results may occur.
A jumper is referred to as open or unjumpered when the plug is pushed down over only one pin or if there is no plug at all. When the plug is
pushed down over two pins, the jumper is referred to as jumpered. The jumper setting is often shown in text as two numbers, such as 1-2. The
number 1 is printed on the circuit board so that you can identify each pin number based on the location of pin 1.
Figure 2 shows the location and default settings of the jumper blocks on your system board. See
functions of your system's jumpers.
Figure 2. System Board Jumpers
I/O Ports and Connectors
Interrupt Assignments
Memory Allocations
Table 1 for the designations, default settings, and