
Re: The Forgotten Fifth Generation
First of all, there was a computer from the Japanese ICOT "Fifth Generation Computer Systems (FGCS)" project that was commercially sold. Mitsubishi sold a couple versions of the ICOT "PSI" ("Personal Sequential Inference") computer. Its operating system was written in a language called "KL0", which was a derivative of Prolog that was expanded so that it could also be used as a kernel development language. (That is where the "KL" in the name came from-- it was "Kernel Language 0". As an aside, there was also a KL1 language that was concurrent so that it could run on massively parallel ICOT research inference machines known as "PIM"s.) The KL0 language's code execution was sped up by being run on a custom microcoded accelerator chip in the system designed specifically to execute KL0. This custom processor was more or less an extended "Warren Abstract Machine (WAM)" implemented in hardware. Anyway, the Mitsubishi PSI was targeted specifically towards natural language processing and automatic document language translation, and was sold to Japanese multinational companies for that purpose. If I remember correctly, only a few hundred Mitsubishi PSI's were sold, so they were not common machines.
With that said, the history portion of Liam Proven's article was an absolute mess. The rise of the specialty LISP and Prolog machines of the 1980's was a result of the keen interest in expert systems at the time. Expert Systems were considered to be bleeding edge A.I. in those days (and a third of Fortune 500 companies were using them), but if you gave the expert systems more than a few hundred rules to follow in their decision trees they became painfully slow at returning answers. Thus several research efforts around the world started up to find ways to speed up them so that they could use exponentially more rules to make inferences from so that they could be used to in broader and broader knowledge domains and be ever more flexible, usable, and powerful. This research lead to the development of the before-mentioned Warren Abstract Machine and Prolog compilers based on it at the University of Edinburgh, *many* custom LISP and Prolog accelerator chips from many different universities, and the Japanese FGCS project, which hoped to both use hardware accelerators *and* run them in parallel for an even bigger speedup.
What killed specialty hardware systems like the Symbolics LISP machine and the Mitsubishi PSI was Moore's Law and bigger better-funded companies making huge advances with developing high-performance RISC CPU's. UNIX workstations in particular took over this space because UNIX systems were very general-purpose and could be used for lots of things, not just specialty A.I. applications, and by the early 90's Sun SPARCstations and Digital DECstations with their SPARC and MIPS RISC CPU's, respectively, had become *faster* at running Prolog and LISP than the specialty machines with the hardware LISP and Prolog accelerators were. (There is a great PDF report written by DEC about this here: https://www.info.ucl.ac.be/~pvr/PRL-TR-36.pdf ) What were you going to spend your tens of thousands of dollars on if you were a company? Buying a specialty hardware Prolog or LISP machine or a far more useful and flexible UNIX workstation that could also run LISP or Prolog faster than the specialty machine? It was a no-brainer decision. Even the Japanese FGCS project saw that it was futile to keep producing their custom inference machines when competing against the ever-rising performance of SPARC CPU's and created a UNIX KL1 compiler so that they could start porting their inference machine software over to SPARC machines to continue their research. So it wasn't so much a "MIT/Stanford" style of programming vs. a "New Jersey" style of programming war like the author tried to portray it as. Instead, it was that better funded large CPU companies were able to increase the performance of their CPU's faster than university researchers and tiny niche workstation companies could increase the performance of their custom single-use special purpose chips. Just like the Commodore Amiga and it's custom chipset, the Symbolics LISP machine and the Mitsubishi PSI had the performance edge in their particular niche at first, but their specialty custom nature and disadvantage in R&D funding eventually allowed more standardized, general purpose, and better-funded platforms to steamroll over them and crush them in the market.