RedBoot> fis free
  0xA8730000 .. 0xA87E0000
RedBoot>

ubuntu@ubuntu-laptop:~/openwrt/atheros$ bc
bc 1.06
Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'. 
obase=16
ibase=16
A87E0000 - A8730000
B0000
ubuntu@ubuntu-laptop:~/openwrt/atheros$