CIS 4930.1194X/6930.1078X Spr.'00
Assignment #6 (Course Part IV, Weeks 7-8)
Misc. Future Computing Technologies

Please continue to follow the general advice on reading assignments from the first week's assignment.

Reading assignment:

For these two weeks we will be covering a wide variety of miscellaneous interesting possibilities for radical future computing technologies (well beyond semiconductor technology).

The following chapter of the course manuscript briefly summarizes some properties of some of the technologies we will be covering, and analyzes the benefit of reversibility under the various technologies.

Lectures 18-19: Superconducting logic circuits

Here's a little bit of background information on the properties of superconductors.

This chapter from the famous Feynman Lectures on Physics contains further depth and discusses the Josephson junction, which is the primary active element in most superconducting circuits. This article, though it does not talk about computational applications of superconducting per se, gives an interesting and insightful discussion of how electrodynamics (Maxwell's equations) can be understood to follow simply from the quantum wave mechanics of electrons, as illustrated by their behavior in superconducting materials.  This article is also somewhat helpful for understanding some properties of superconductors. This article (which I also assigned in week 2) describes an early Josephson-junction logic style that is reversible and is shown to be capable of less than kT dissipation per operation. This brief introductory article describes a later, more thoroughly developed Josephson-junction logic technique, "Rapid Single Flux Quantum", that has been experimentally verified to operate at frequencies in the hundreds of gigahertz. This is a longer, more detailed and technical review of the RSFQ technique. This paper describes how RSFQ is being used in a planned PetaFLOPS-scale supercomputer. And, here is a web page with a rich archive of other papers on RSFQ. Here is a paper on (relatively) high-temperature superconducting devices. Lectures 20-21: DNA computing

An introductory article from the guy who started the field (fad?):

His original article that started things going: My own (abandoned) PhD proposal on DNA computing: This next paper is very important because (in contrast to all the others) it presents a more pessimistic side of the DNA computing coin, which I am sympathetic with.  After working in the field, I personally feel it's unlikely that DNA computing will ever be a competitive computing technology.  See this paper for some reasons. Some interesting articles from the first DNA computing workshop: This next one I find particularly interesting as it shows how to compute 1-D and 2-D cellular automata using self-assembly of 2-D and 3-D DNA structures. Slightly more recent articles: Computation via control of protein transcription in living cells: Some good web sites: Lecture 22: Nano-mechanical logic

The primary work in this area has been done by the molecular-nanotechnology pioneers/visionaries Eric Drexler and Ralph Merkle.

Here is Drexler's treatise on nano-mechanical "rod logic":

Here is Merkle's article on a couple of different reversible mechanical logics. Lecture 23: Molecular Electronics

Written assignment #6: (due Mon. 3/13, just after Spr. break)

This is our standing written assignment.  It should be on the subject of the above lectures and reading material.