I visited Livermore in 1971 and they showed me a 7600. I had just designed a character generator for a high-resolution CRT with 27 ns pixels, which I thought was pretty fast. It was a shock to realize that the 7600 could do a floating-point multiply for every dot that I could display!
In 1975 or 1976, when the Cray 1 was introduced, ... I heard him at Livermore. He said that he had always hated the population count unit, and left it out of the Cray 1. However, a very important customer said that it had to be there, so he put it back. This was the first time I realized that its purpose was cryptanalysis.
Butler Lampson was clearly impressed by the 7600.