Rom Monitor Overview And Basic Procedures - Cisco 1100 Series Hardware Installation Manual

ROM Monitor Overview and Basic Procedures

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ROM Monitor Overview and Basic Procedures
This chapter provides an overview of ROM Monitor concepts and operations.
This chapter includes the following main topics:
ROM Monitor Overview
The ROM Monitor is a bootstrap program that initializes the hardware and boots the Cisco IOS XE software
when you power on or reload a router. When you connect a terminal to the router that is in ROM Monitor
mode, the ROM Monitor command-line interface (CLI) prompt is displayed.
If your system (router, switch, or access server) does not find a valid system image to load when it is booting,
the system will enter the ROM monitor mode. ROM monitor (ROMMON) mode can also be accessed by
interrupting the boot sequence during startup.
The ROM monitor mode is used to:
• specify config-register value to use for the next boot up
• boot a valid IOS XE image
• bypass NVRAM settings and config-register value for password recovery
The ROM Monitor software is known by many names. It is sometimes called ROMMON because of the CLI
prompt in ROM Monitor mode. The ROM Monitor software is also called the boot software , boot image ,
or boot helper . Although it is distributed with routers that use the Cisco IOS XE software, ROM Monitor is
a separate program from the Cisco IOS XE software. During normal startup, the ROM Monitor initializes the
router, and then control passes to the Cisco IOS XE software. After the Cisco IOS XE software takes over,
ROM Monitor is no longer in use.
Environmental Variables and the Configuration Register
Two primary connections exist between ROM Monitor and the Cisco IOS XE software: the ROM Monitor
environment variables and the configuration register.
ROM Monitor Overview and Basic Procedures, page 41
Hardware Installation Guide for the Cisco 1100 Series Integrated Services Router
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