Appendix B Cisco 4000 Series Virtual Configuration Register; Virtual Configuration Register Settings; Table B-1 Virtual Configuration Bit Meanings - Cisco EF4116 Hardware Installation And Maintenance Manual

A P P E N D I X
Cisco 4000 Series Virtual
Configuration Register
This appendix describes the Cisco 4000 series virtual configuration register, the factory default
settings, and the procedures for changing those settings.

Virtual Configuration Register Settings

The Cisco 4000 series has a 16-bit virtual register, which is written into the nonvolatile random
access memory (NVRAM). Use the processor configuration register information contained in this
appendix to do the following:
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Table B-1 lists the meaning of each of the virtual configuration memory bits.
Table B-1
Bit No. Hex
00–03
06
07
08
10
11–12
13
14
15
B
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.
Virtual Configuration Bit Meanings
Meaning
0x0000–0x000F Boot field (see Table B-2)
0x0040 Causes system software to ignore nonvolatile memory contents
0x0080 OEM bit enabled
0x0100 Break disabled
0x0400 IP broadcast with all zeros
0x0800–0x1000 Console line speed
0x2000 Boots default ROM software if network boot fails
0x4000 IP broadcasts do not have net numbers
0x8000 Enables diagnostic messages and ignores NVRAM contents
Cisco 4000 Series Virtual Configuration Register B-1