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Chapter 4 Hardware Configuration 81
About the Main Logic Board Jumpers
The jumpers on the main logic board have the following functions:
■ To configure the serial ports for either EIA-423 or EIA-232D operation. For
information about the EIA-423/232D jumper settings, and about configuring
them, see “About Serial Port Jumpers” on page 82.
■ To affect the operation of the flash PROM located on the main logic board. For
information about the flash PROM jumper settings, see “About Flash PROM
Jumpers” on page 83.
Modifying jumper settings can only be performed by a qualified service provider.
For more information about changing jumper settings, see the Sun Enterprise 220R
Server Service Manual.
Jumpers are marked on the main logic board with jumper addresses. For example,
the serial port jumpers are marked J2604 and J2605. Jumper pins are located
immediately adjacent to the jumper address. Pin 1 is marked with an asterisk (*) in
one of the positions shown below.
Pins
Jumper address
J X X X X
*
*
*
*
*
*
Asterisk indicates pin 1