http://tasvideos.org/forum/viewtopic.php?p=356972#356972

the entropy data that's passed through the sha-1 function is made from a bunch of different things that i partially listed above.

-vcount is the vertical line counter, 0-262 each vframe
-the current value of timer0, a timer moving at the speed of system bus(16.78 mhz) counting 0-65535
-the mac address
-the current value of the tick system which is a special counter that is part of the sdk and not considered in normal rnging because it's always 0 at that point
-the current vframe number
-the current graphics engine status
-the current realtime clock values for y/m/d and h/m/s
-microphone sampling data result
-address in ram of the last microphone sampling data
-current touch panel status and info- all ranging from 0-65535
-current sel/sta/a/b/udlr/lpad/rpad key input
-current x/y/closed input
-the wireless rssi pool that generates random numbers- depends on wireless module received signal intensity.