Every Cisco router has a 16-bit software register written into its NVRAM. The default settings are set to load the Cisco IOS from flash memory and to look and load the startup config file from NVRAM. But, as I have said, you can change those settings.
Let's simplify the math, but first let's look at what hex numbers are:
The binary bit that changes is what instructs the router on the boot up process to look at NVRAM for the startup configuration file (0x2102) or not to look or ignore the startup configuration in NVRAM (2,142) and just load the IOS into RAM.
Here is how you do the math manually:
These are not the only settings you could change the registry to; the following table shows you the bit and hex values, along with a brief description of what they do:
|
Bit |
Hex |
Description |
|
7 |
0x0080 |
OEM bit enabled |
|
8 |
0x101 |
Break disabled... |