Difference between System Bootstrap and Cisco IOS

I'm new to the Cisco stuff and I'm just playing around with routers such, and am curious what's the difference between the System Bootstrap and the Cisco IOS?

router#show ver
Cisco Internetwork Operating System Software
IOS (tm) C2600 Software (C2600-IK9S-M), Version 12.2(31), RELEASE SOFTWARE (fc2)

Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2005 by cisco Systems, Inc.
Compiled Thu 11-Aug-05 17:24 by tinhuang
Image text-base: 0x8000808C, data-base: 0x8128D9F4

ROM: System Bootstrap, Version 12.2(6r),  RELEASE SOFTWARE (fc1)
ROM: C2600 Software (C2600-IK9S-M), Version 12.2(31), RELEASE SOFTWARE (fc2)

Should they also always be on the same main version number?  Also I know Cisco provides the IOS's to download and upgrade,but how about the System Bootstrap?

Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

The IOS is the full Cisco Operating system that permits the Cisco device to perform all of its routing functions.  
The System BootStrap in ROM: contains the minimum code to bring up the Cisco device and permit you to operate minimumly; this should at least permit you to configure the 2600 to download a usable Cisco IOS in the event that the IOS in NVRAM is trashed.  

oh, Cisco IOS, OS, CatOS are updated on a regular basis and I also assume that the ROMs are also.  I usually don't pay attention to those version numbers unless there are issues.  

The ROMs are soldered on; BTW so they can't be changed.


Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Don JohnstonInstructorCommented:
The Bootstrap is code in ROM that instructs the router on how to boot.

The bootstrap code in Cisco ROM instructs the router to first check the boot field of the config-register. If it's 0x0, ROM monitor is loaded, If it's 0x1, the mini-IOS is loaded. If the boot field is anything else, the config file in NVRAM is examined for any commands that start out "boot system". If there are any, the remaining part of that command is parsed and the IOS is loaded from the specified location.

Absent any boot system commands, the first file in flash is loaded.

If there is no file in flash, a netboot is attempted.

As ECNSSMT points out, the IOS is the operating system.

Ultimate Tool Kit for Technology Solution Provider

Broken down into practical pointers and step-by-step instructions, the IT Service Excellence Tool Kit delivers expert advice for technology solution providers. Get your free copy now.

Don JohnstonInstructorCommented:
Also, not all ROM's are soldered. I've upgraded Boot ROM on a couple different routers. In fact, the last time I did it was to a 2500 and it was free from Cisco. I haven't looked into the 2600's though.

Don JohnstonInstructorCommented:
I don't doubt that there are Cisco devices with removable parts including ROMs.  Considering how many versions of OSes Cisco has for their devices, it would be hard enough not to imagine that they have hardware teams constantly revising or improving their hardware.

It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.