Sun Microsystems 220R service manual How to Set the Flash Prom Jumpers, What Next

Serial port jumper	A shunt on pins 1	A shunt on pins 2	The default shunt
	and 2 selects	and 3 selects	is on pins
J2604	RS-232D	RS-432	2 and 3
J2605	RS-232D	RS-432	2 and 3

3.15.3What Next

4Complete the following task to reassemble the system:

Section 2.7 “How to Replace the System Cover” on page 67

3.16How to Set the Flash PROM Jumpers

The system uses flash PROMs to permit the reprogramming of specific code blocks that are held in non-volatile system memory, and to permit remote reprogramming of that code by an authorized system administrator over a local area network.

Two jumpers, J2703 and J2804, on the main logic board affect flash PROM operation. The default shunt setting of J2703 is on pins 1 and 2. Placing a shunt on pins 2 and 3 enables reprogramming of the flash PROM.

When you reprogram NVRAM, it stores the old program in the high half of NVRAM as a backup copy, in case something goes wrong in the new program. The jumper switches enable you to select which half of NVRAM you want to boot from: the low-half (or normal, default) or the high-half. This means that you can set the jumpers to select either “high-half booting” or “low-half booting.”

3.16.1Before You Begin

Complete these tasks:

Section 2.1 “How to Power Off the System” on page 54

Section 2.4 “How to Position the System for Service” on page 60

4Section 2.6 “How to Remove the System Cover” on page 65 Section 2.8 “How to Avoid Electrostatic Discharge” on page 69

124 Sun Enterprise 220R Server Service Manual ♦ January 2000, Revision A