Change configuration registry on older Cisco routers

Contributed by qmchenry February 21, 2006  
Tagged: Cisco router

I ran across an ancient 2500 series router today and had to go through a password recovery. The rommon version was earlier than any I’d seen before. The help functionality was very lean. Here’s how to set the confreg for these geezers.

If the rommon help screen (type H to see it) says to type O to look at the configuration registry, you set it like this:

o/r 0x2142

I manually power cycled after this and had success. When you get things working again, I suggest backing away very slowly and cautiously.