The Universal Audio EMT250 was announced today. In the video on the product page, you can see Barry Blesser talking about the original hardware, and that it was intended to emulate a hall. You can also see a blurry drawing of the ALGORITHM about halfway through the video. It looks a lot like what Casey described earlier in this thread: 3 parallel combs, with 3 taps per comb. The taps are combined by something that is obscured by a big graphic of the EMT250 box, and then sent into 3 or 4 delay lines. There is a bunch of other stuff that is hard to read. Still, interesting that they would use the algorithm drawing as part of their promotion. I don't think I would do that for my own work.
Sean