HI
0x201 means it will boot from the first image it finds in flash , 0x2102 is the default standard and 0x102 is basically the same but does not boot into rom if there's a failure during bootup
http://www.cisco.com/c/en/us/support/docs/routers/10000-series-routers/50421-config-register-use.html#config-reg-meaning
If that answers your query pls rate the post thanks