The Cisco Configuration Register
This is a rather obscure setting. As it applies to password recovery techniques, it seems straight forward. There are actually several other settings that can be set to make the router do various things at boot. Like:
Boot Settings
| Boot to Bootstrap |
| Boot from EPROM |
| Boot from Flash |
Console Baud Rate Settings
| 1200, 2400, 4800, and 9600 |
Other Settings
| Fast Boot |
| Ignore Configuration on Startup (this is a key setting) |
| Enable OEM Bit (ignore Cisco startup message) |
| Disable the break key |
| IP Broadcast with all zeros |
| Boot ROM if Netboot fails |
| IP Broadcast if no net number |
| Enable diagnostics and ignore NVRAM |
| Do not use secondary bootstrap |
These are it as best I can tell. I actually have a Configuration Register Calculator much like the Subnet Calc. It can take a HEX setting (or the binary) and tell you what settings are enabled or you can select the settings you want and it will tell you the HEX or binary value of the Conf Reg.