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This appendix describes the Cisco 1600 series router ROM monitor (also called the bootstrap program). The ROM monitor firmware runs when the router is powered up or reset and helps to initialize the processor hardware and boot the operating system software. You can perform certain configuration tasks, such as recovering a lost password or downloading software over the console port, by using ROM monitor.
This appendix contains the following sections:
To use the ROM monitor, you must have console port access. Refer to the installation chapter in the hardware installation guide that came with your router for information on how to connect the router console port to a PC or terminal.
From the operating system software, you can configure the router to remain in the ROM monitor the next time it boots. Set the virtual configuration register bits 3, 2, 1, and 0 to zero by entering the following configuration command at the user-level EXEC prompt:
router> config-reg 0x0
Enter the reload command to reboot the router with the new configuration register value, 0x0. The router remains in the ROM monitor and does not boot the operating system.
As long as the configuration value is 0x0, you must manually boot the operating system from the console. Refer to the boot command in the section "Command Descriptions" later in this appendix.
 | Time Saver Break (system interrupt) is always enabled for 60 seconds after the router reboots, regardless of whether it is configured on or off in the configuration register. During this 60-second window, you can break to the ROM monitor prompt by pressing the Break key. |
The Cisco 1600 ROM monitor prompt looks like this:
rommon 1>
In this example, 1 is the line number and is incremented at each prompt.
Enter ? or help at the ROM monitor prompt to display a list of available commands and options, as follows:
rommon 1> ?
help monitor builtin command help
boot boot up an external process
dir list files in file system
dev list the device table
confreg configuration register utility
reset system reset
stack produce a stack trace
context display the context of a loaded image
frame print out a selected stack frame
sysret print out info from last system return
meminfo main memory information
xmodem x/ymodem image download
rommon 2>
Commands are case sensitive. You can halt any command by pressing the Break key on a terminal. If you are using a PC, most terminal emulation programs halt a command when you press the Ctrl and the Break keys at the same time. If you are using another type of terminal emulator or terminal emulation software, refer to the documentation for that product for information on how to send a Break command.
The following ROM monitor commands are among the most useful:
dev
dir flash:
You can use console download, a ROM monitor function, to download over the router console port either a software image or a configuration file. After download, the file is either saved to the Flash PC card or to main memory for execution (image files only).
Use console download when you do not have access to a Trivial File Transfer Protocol (TFTP) server.
 | Caution If you are using a PC to download a Cisco IOS image over the router console port at 115,200 bps, ensure that the PC serial port is using a 16550 universal asynchronous transmitter/receiver (UART). If the PC serial port is not using a 16550 UART, we recommend using a speed of 38,400 or less when downloading a Cisco IOS image over the console port. |
Following is the syntax for the console download command:
xmodem[-ycefrx] [-sbaud_rate] file_name
Following is a syntax description for the console download command:
| y | (Optional) Sets the router to perform the download using ymodem protocol. Default is xmodem protocol. The protocols differ as follows:
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c | (Optional) Performs the download using CRC-16 error checking to validate packets. Default is 8-bit CRC. |
| e | (Optional) Erases Flash memory before starting the download. If there are other Flash memory partitions, this option erases the first partition only. |
| f | (Optional) Erases the entire Flash memory (full erase). |
| r | (Optional) Image is loaded into DRAM for execution. Default is to load the image into Flash memory. |
| x | (Optional) Image is loaded into DRAM without being executed. The image can then be launched with the ROM monitor launch command. |
| -s baud_rate | (Optional) Specifies the download baud rate. Options are 1200, 2400, 4800, 9600, 19200, 38400, 115200.
Note--Use this option only when the router is directly connected to the host PC from which the software image will be downloaded. Do not use this option when downloading the software image over a modem connection. Default is baud rate currently specified in the configuration register. This rate applies only during the data transfer. Once the data transfer is complete, the baud rate reverts to the rate specified in the configuration register. |
| file_name | The name of the system image file or the system configuration file. In order for the router to recognize it, the name of the configuration file be router_config. |
Because the ROM monitor console download uses the console to perform the data transfer, error messages are only displayed on the console when the data transfer is terminated.
If an error does occur during a data transfer, the transfer is terminated, and an error message is displayed. If you have changed the baud rate from the default rate (with the -s option), the error message is followed by a message telling you to restore the terminal to the baud rate specified in the configuration register.
Most debugging commands are functional only when Cisco IOS software has crashed or is halted. If you enter a debugging command and Cisco IOS crash information is not available, you see the following error message:
"xxx: kernel context state is invalid, can not proceed."
The following are debugging commands:
context
sysret
meminfo
The virtual configuration register resides in NVRAM and is identical in operation to other Cisco routers. You can view or modify the virtual configuration register from either the ROM monitor or the operating system software.
To change the virtual configuration register from the ROM monitor, enter confreg by itself for menu mode, or enter the new value of the register in hexadecimal.
confreg [hexnum]--Change the virtual configuration register to the value specified. The value is always interpreted as hexadecimal. Entering confreg without an argument displays the contents of the virtual configuration register and a prompt to alter the contents by describing the meaning of each bit.
In either case, the new virtual configuration register value is written into NVRAM, but does not take effect until you reset or power-cycle the router.
The following display shows an example of menu mode:
rommon 7> confreg
Configuration Summary
enabled are:
console baud: 9600
boot: the ROM Monitor
do you wish to change the configuration? y/n [n]: y
enable "diagnostic mode"? y/n [n]: y
enable "use net in IP bcast address"? y/n [n]:
enable "load rom after netboot fails"? y/n [n]:
enable "use all zero broadcast"? y/n [n]:
enable "break/abort has effect"? y/n [n]:
enable "ignore system config info"? y/n [n]:
change console baud rate? y/n [n]: y
enter rate: 0 = 9600, 1 = 4800, 2 = 1200, 3 = 2400 [0]: 0
change the boot characteristics? y/n [n]: y
enter to boot:
0 = ROM Monitor
1 = the boot helper image
2-15 = boot system
[0]: 0
Configuration Summary
enabled are:
diagnostic mode
console baud: 9600
boot: the ROM Monitor
do you wish to change the configuration? y/n [n]:
You must reset or power cycle for new config to take effect
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