The interesting point, though, was that the specific goals were not clearly related to the fundamental reasons for doing it. And as it turned out, most of the research topics (but not all, IIRC) were really boosted by work in graphics co-processors.
As to the 5th generation computer project, what little I've read so far has more or less convinced me that special-purpose processors will never be better than general-purpose ones, at least not for general-purpose computing (which, ultimately, was the aim of the project).
I'm saying that as a dyed-in-the-wool symbolist btw (and a long-time Prolog user). Special-purpose processors to make my Prolog go faster is something I'd love to get my hands on- but, for most people? I think it's not even number 1000 in their list of priorities ot improve computing performance.
There was a lot of research for AI hardware in the 80s and also for Prolog hardware. I once saw a Japanese Prolog Machine (a special purpose workstation with a Prolog environment), but I didn't have the chance to actually use it.
With faster/cheaper Intel or RISC processors and a lack of research funding, the topic of specialized hardware was mostly ending in the early 90s.
Given the historical circumstances, I'll be he would prefer they were trying to build a parallel Lisp machine.