What Kind of Neural Networks Did Robert Heck-Nealsons Use?

Robert Heck-Nealsons was a big influence on the neural network movement. He also had a company HNC which was an early neural network company for fraud, credit card fraud detection. I've often wondered whether there was something there that I just didn't understand. But I'd love if anybody out there has actually read his papers and understands them because I have never had enough energy to do that.