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Setting the conf-reg Value in ROM Monitor
There are two different versions of the ROM monitor used on Cisco
routers. On the 2500 series, routers use a very terse ROM monitor
compared to the 1600, 3x00, 4x00, and 7x00 series routers. When in
rommon on a 2500 series, the rommon prompt looks like this:
>
To get help, you can type ? or H, which will list the available ROM
monitor commands. To set the conf-reg value on a Cisco 2500, type
the O/R command combination and the desired conf-reg setting
(with no line spaces):
>O/R0x2002
Then, initialize the router:
>I
System Bootstrap, Version 11.0(10c), SOFTWARE
Copyright © 1986-1996 by Cisco Systems
This will boot the 2500 series router using the new conf-reg setting.
On the 1600, 2600, 3x00, 4x00, and 7x00 series, ROM monitor is
slightly more friendly. The prompt looks like this (the number in the
prompt is the command history value):
rommon 3 >