I have an FB^3 program that calculates the nth prime number (1 is the 
0th prime, 2 the 1st, etc) using a Minsky machine. A Minsky machine 
is an abstract machine (like a Turing machine) that only allows 
variables to be incremented or decremented by 1 and to make state 
transitions depending on whether or not the variable associated with 
the state is zero or not.

It is a very s-l-o-w way to calculate prime numbers but some nice 
things about it are...

it animates the state transitions and shows the variable values as 
the calculation proceeds and

you can stop it at any time, save the state of the machine and 
continue the calculation later (I have been calculating the 24th 
prime number for nearly 2 months now, off and on).

I will share the working program with any one who wants it. Email me 
privately and have Stuffit 5.x.

-- 
Charlie Dickman
charlied@...