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Cisco 7201 Installation and Configuration Guide
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Appendix B Using the CompactFlash Disk Boot Environment Variables
The format command places a processor-specific file system on the CompactFlash Disk so that the ROM
monitor software can read the CompactFlash disk media. If you plan to use the boot or dir commands
at the ROM monitor prompt (rommon>), you might need to reformat your CompactFlash Disk if it was
not already formatted on a like system processor.
For simple file storage and retrieval functions, CompactFlash Disks can be interchanged between any
Cisco 7201 router.
Note The CompactFlash Disk in the Cisco 7201 router is supported on the c7200p-kboot-mz image.

System Memory and Software Image Functions and Interactions

The read-only memory (ROM) monitor image on your system performs important functions, such as
running a brief set of system diagnostics, and initializing the hardware. This image gains control at reset
or power on, or after a nonrecoverable event (such as a bus error). The ROM monitor software image has
a rudimentary user interface that is recognizable by way of the ROM monitor prompt (rommon>). The
ROM monitor software image has console drivers and trap handlers for parity and bus errors; however,
the ROM monitor does not have any network interface code and it cannot boot an image over the
network.
Note The ROM monitor is only able to load an image from boot flash memory or a CompactFlash Disk.
By default, and as a result of a reset or power on, the ROM monitor loads the boot image from boot flash
memory. If the ROM monitor cannot find a bootable image in boot flash memory, it searches the
CompactFlash Disk for the first bootable image. Normally, this would be the c7200p-kboot-mz image.
The boot image, when loaded, looks in the boot environment variables—stored in nonvolatile
random-access memory (NVRAM)—to determine the location of the Cisco IOS software image and the
configuration to use. If boot environment variables are not defined, the system will boot the first image
found on the CompactFlash Disk.
The operation of the boot environment variables is described in the “Boot Environment Variables”
section, which follows.
Boot Environment Variables
The contents of the boot environment variables, which are stored in the configuration file in NVRAM,
determine the actions your system takes on bootup. To see the current settings of these variables, use the
show bootvar command as follows:
Router> show bootvar
BOOT variable =
CONFIG_FILE variable =
Current CONFIG_FILE variable =
BOOTLDR variable does not exist
Configuration register is 0x100