Cisco IOS Configuration Register Decoder

0x

Bit	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
Value	NAN	NAN	NAN	NAN	NAN	NAN	NAN	NAN	NAN	NAN	NAN	NAN	NAN	NAN	NAN	NAN

Boot field (bits 0-3)

Sequence	Meaning
0000	Boot directly to ROMMON.
0001	Boot to the first valid Cisco IOS image on flash memory (flash:)
0011 to 1111	Read from NVRAM for valid boot system commands unless bit 6 is set to 1, of which NVRAM is bypassed. If there are no valid boot system commands, boot to the first valid Cisco IOS image on flash memory. If there are no valid images on flash memory, attempt to netboot by connecting to a TFTP server requesting for a default filename, which contains the octal representation of NAN: ciscoNAN-<suffix>. If cannot connect to a TFTP server, boot to ROMMON after unsucessful tries if bit 13 is 1, otherwise if bit 13 is set to 0, try indefinitely.

Bit	Value	Meaning
15	NAN	NIL
14	NAN	NIL
13	NAN	NIL
10	NAN	NIL
9	NAN	NIL
8	NAN	NIL
7	NAN	NIL
6	NAN	NIL

Baud rate (bits 5,11,12)

The following TTY console settings always apply

Data bits: 8
Parity: none
Stop bits: 1
Flow control: none

The bits per sec/baud rate will be set as follows:

5	11	12	Meaning
0	0	0	9600
0	0	1	1200
0	1	0	4800
0	1	1	2400
1	0	0	19200
1	0	1	57600
1	1	0	38400
1	1	1	115200