D-1
Cisco 7401ASR Installation and Configuration Guide
OL-5419-01 B0
APPENDIX
D

Configuration Register Information

The following information is found in this appendix:
•Configuration Bit Meanings, page D-1
•Displaying the Configuration Register While Running Cisco IOS, page D-5
•Displaying the Configuration Register While Running ROM Monitor, page D-5
•Setting the Configuration Register While Running Cisco IOS, page D-6
•Setting the Configuration Register While Running ROM Monitor, page D-6

Configuration Bit Meanings

Use the processor configuration register information contained in this appendix to do the following:
•Set and display the configuration register value
•Force the system into the bootstrap program
•Select a boot source and default boot filename
•Enable or disable the Break function
•Control broadcast addresses
•Set the console terminal baud rate
•Load operating software from ROM
•Enable booting from a Trivial File Transfer Protocol (TFTP) server
Table D -1 lists the meaning of each of the configuration memory bits. Following the table is a more
in-depth description of each setting.
TableD-1 Configuration Register Bit Settings
Bit No. Hex Meaning
00–03 0x0000–0x000F Boot field
06 0x0040 Causes the system software to ignore nonvolatile random-access
memory (NVRAM) contents
07 0x0080 OEM (original equipment manufacturer) bit enabled
08 0x0100 Break disabled
10 0x0400 IP broadcast with all zeros