Specifically, he wrote a computer program to look for primes.

https://groups.google.com/forum/#!topic/sci.math/AZD_CalO7as

I am not an expert, but it seems he wrote some highly optimized code to do it:

> The search was conducted over 10 days on a AMD 1800XP and checked > about 20,667,931,547 Potential AP 22's per Second.