older DEMO program

[Bill Bouris]

Dear Sir,
 
I remember using an older DEMO program on your site
that performed calculations on large numbers. It was the
original DEMO calculator instead of the new PI calculator.
Is that DEMO still accessible online ?? somewhere ???
 
Bill Bouris
 
I want to compute 2^(2^(2^126-1)-1) mod 2^(2^127-1)-1,
or a primality test on C5. It did such huge calculations using a
modular technique without creating the big numbers themselves.
If this calculation is equal to +1 (OR) (2^(2^127-1)-2, then
C5 is prime! according to (my) Riesel's Theorem. Only one
calulation is needed. Can you help me???