Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!rutgers!aramis.rutgers.edu!athos.rutgers.edu!nanotech From: landman@hanami.eng.sun.com (Howard A. Landman x61391) Newsgroups: sci.nanotech Subject: Re: Simulations of Nanotech Tools Message-ID: Date: 7 Nov 89 21:24:45 GMT Sender: nanotech@athos.rutgers.edu Organization: Sun Microsystems, Mountain View Lines: 55 Approved: nanotech@aramis.rutgers.edu In article raburns@sun.com (Randy Burns) writes: > 2) I got the distinct impression that Drexler was expecting some > substantial breakthroughs in artificial intelligence. Having > worked at Teknowledge, I'm now rather skeptical of this. How > important would AI really be to make nanotech work? JoSH responds: > 2. AI is not terribly important, though we will need an easily foreseeable > advancement in CAD/CAM and simulation capabilities. No AI papers, > for example, were given at the conference. As a CAD professional and an attendee at the conference, I can perhaps shed some light on this point. I, too, found distressing the way EoC cavalierly glossed over CAD and DA problems for nanotech with the argument that super-AI would solve all those problems for us. Very little industrial-strength CAD is done using AI-based tools today, and the fraction of AI in a field like that tends to *decrease* as the field matures. For example, computer Chess used to be an AI topic but is now merely an engineering topic, a fact which seems to give many AI people heartburn. All the programs in the latest international computer Chess championship were written in C, and many of them had special-purpose hardware. At first it might seem that existing tools for system and logic-level design would still be adequate for nanotech, at least some portions of it like molecular electronic computers. It's rather obvious that the lower levels need to be completely different. The amount of work to create the nanotech equivalent of a silicon compiler is immense. However, I've done some experiments which indicate that perhaps even the higher levels of present-day tools are inadequate. For example, I created a dummy technology in which Fredkin gates were cheap and fast but normal logic gates (nand, nor, invert) were expensive and slow. Using one of the best commercial logic synthesis tools, I tried to synthesize a circuit using this technology. It made no use whatsoever of the Fredkin gates, and instead produced a netlist consisting entirely of ordinary gates. This indicates to me that substantial theoretical work still needs to be done in the area of logic synthesis for conservative/reversible logic, before we can design large systems using such technologies. I know of no one (besides myself) who is even aware of this problem, let alone working on it. And this is just one *small* area of CAD for nanotech. In electronics, CAD tools tend to lag about one generation behind the hardware. That is, today's tools are perfect for the system you built a couple years ago, but they never quite handle what you need for *today's* design. Also, support for mainstream technologies is always better than that for fringe technologies. Even today, design tools for ECL and GaAs are more limited than those for CMOS. In the early days of nanotech, I do not expect CAD to be at all well developed. Only after nanotech surpasses existing technologies in volume will there be sufficient incentive for the tools to become powerful, stable, elegant, and well-integrated. Howard A. Landman landman%hanami@eng.sun.com