New and Improved

Last update: 16 October 2017

Update Log (covers finer-grained changes)

Marinchip Systems: Documents and Images

In 1977, I founded Marinchip Systems, with the goal of developing personal computing hardware and software that provided the power and convenience afforded by contemporary timesharing systems at a fraction of the price. Starting in 1978, Marinchip delivered the first true 16-bit personal computer on the S-100 bus, based on the Texas Instruments TMS9900 microprocessor. This document is an archive of documents and photos from the Marinchip era, including scanned copies of many of the hardware and software manuals.

ISBNiser: Validate, Convert, and Link to ISBN-10 and ISBN-13 Codes

International Stanard Book Numbers (ISBNs) provide a unique identification for each edition of a published book, and are essential when citing works or linking to them on on-line booksellers. This command line utility, implemented in Perl, validates both older ISBN-10 and current ISBN-13 formats, converts between them, and creates links which can be used to order the book from Amazon, optionally crediting the purchase to an Amazon Associates account.

Apparent Diurnal Variation in Background Radiation

Between 1998 and 2001 I measured background radiation in Fourmilab's computer lab with a Geiger-Müller tube interfaced to a computer. Analysing the data revealed both an apparent divergence from a Gaussian distribution of counts per minute and a variation in background radiation with time of day. This page presents the data, analysis, speculation on possible causes, and provides a link whence you can download the data and programs for your own investigations.

UNUM: Unicode/HTML/Numeric Character Code Converter

Web authors who use characters from other languages, mathematical symbols, fancy punctuation, and other typographic embellishment in their documents often find themselves juggling the Unicode book, an HTML entity reference, and a programmer's calculator to convert back and forth between the various representations. This stand-alone command line Perl program contains complete databases of Unicode characters and character blocks and HTML/XHTML named character references, and permits easy lookup and interconversion among all the formats, including octal, decimal, and hexadecimal numbers. The program works best on a recent version of Perl, such as v5.8.5 or later, but requires no Perl library modules. New version 2.1 (September 2017) updates to the Unicode 10.0.0 and HTML5 standards and adds support for Chinese, Japanese, and Korean character sets.

Little Wars

In this 1913 classic, H. G. Wells essentially single-handedly invented the modern pastime of miniature wargaming, providing a (tin soldier) battle-tested set of rules which makes for exciting, well-balanced, and unpredictable games that can be played by two or more people in an afternoon and part of an evening. Interestingly, he avoids much of the baggage that burdens contemporary games such as icosahedral dice and indirect fire calculations, and strictly minimises the rôle of chance, using nothing fancier than a coin toss, and that only in rare circumstances. This Web edition includes all of the photographs and marginal drawings from the 1913 first edition.


Can't decide? Here's a utility, written in Perl, which makes decisions for you: yes or no, the fuzzier answers of a Magic 8-Ball, or dice throws, using random data from HotBits, the /dev/urandom generator, or Perl's built-in rand() function.


Cellular Automata Laboratory invites you to explore the world of cellular automata with the aid of a high-speed programmable simulator which runs within your Web browser. Cellular automata rules are defined by short programs written in JavaScript or Java. Rule definitions in JavaScript are compiled directly inside the browser and do not require installing a programming environment on your machine. The accompanying on-line laboratory manual explains the theory of cellular automata, how to use the simulator programs, documents the many ready-to-run rules included, describes how to create your own original experiments, and contains a comprehensive bibliography. A development kit supplies source code for all of the rule definitions and the files they use, providing a starting point for your own explorations. New: 2017 update includes browser-based simulation and JavaScript rule definition.


As life inexorably expands from the home planet throughout the galaxy and beyond, there will come a time when our descendents render a new planet habitable every day. Terranova invites you to visit the terraformed planet of the day. New: Planet Maker lets you interactively create planets, cloudy skies, and star fields in your browser.

The Go-Getter

Peter B. Kyne's classic novelette about a young man whose “whatever it takes” attitude has inspired and motivated hundreds of thousands of readers, including this one, for almost a century. This Web edition, reproducing the 1921 first edition, is in the public domain.

The Analytical Engine

In 1837, Charles Babbage invented The Analytical Engine, a mechanical card-programmed digital computer which anticipated almost every aspect of the electronic computers which would not appear for more than a century afterward. These pages are a virtual museum where you can explore the Engine both through historical documents and an emulator which allows you to experience for yourself what it would have been like to program a steam-powered computer. New: 2017 update adds a JavaScript/HTML5 Web-based emulator and several new sample programs.

Pitch Drop

The longest continuously-running scientific experiment demonstrates that even extremely viscous fluids will eventually flow as the liquids they are. Do it yourself instructions are included.

Orbits in Strongly Curved Spacetime

An interactive animation illustrates how orbits around compact objects such as neutron stars and black holes depart drastically from Kepler's laws, and explains why.

Update: January 2017 update uses HTML5/JavaScript animation, eliminating the need for Java, and improves graphics rendering. The original Java version remains available.

The RetroPsychoKinesis Project

Retropsychokinesis is the claimed ability of certain subjects to alter random data generated, but not examined, prior to the time the data are presented to the subject. Crazy, you say! Well, there's certainly no mechanism in mainstream physics which could permit such an effect, yet experiments conducted by a number of different researchers over the last 20 years suggest, compellingly according to some analyses, that the probability of the results obtained in such experiments being purely the result of chance is sufficiently low that they would be considered evidence of a causal mechanism in most scientific disciplines. The archives of the Project provide a broad collection of research reports (reproduced with the permission of their authors and publishers) and literature citations related to this elusive but, if real, profoundly important phenomenon.

Retropsychokinesis Experiments On-line

You can explore the phenomenon of Retropsychokinesis (if indeed it exists) through these on-line experiments. Each presents you with a sequence of random data produced by the HotBits radioactive random number generator which is presented by a visual feedback program. The random sequence is pre-recorded but not examined prior to your performing the experiment. Results are logged in a secure and transparent fashion, and a daily summary of results to date is published on the Web. Complete source code is available for all of the experiment programs.

Update: Twentieth anniversary update adds HTML5/JavaScript visual feedback programs, eliminating the need for Java.

The Probability Pipe Organ

The Probability Pipe Organ lets you run interactive experiments which demonstrate how the results from random data approach the normal distribution expectation as the number of experiments grows large. Update: HTML5 animation eliminates the need for Java applet support. (The Java version remains available.)

The Autodesk File

The history of Autodesk and AutoCAD told through contemporary documents, edited and annotated by Autodesk founder John Walker. You can read this 900 page book on-line on the World-Wide Web, or download a copy to read or print off-line in either PostScript or Adobe Acrobat PDF format. New: Fifth edition (2017) updates to modern Web standards, typography, and navigation.

Project Pluto

In the late 1950s and early '60s Project Pluto aimed at developing a nuclear powered cruise missile which could fly three times the speed of sound at low altitude with unlimited range and deliver nuclear devastation to multiple targets with pinpoint accuracy. It was one of the most bizarre concepts of the age of unlimited nuclear optimism, and got as far as ground testing a full scale flight weight propulsion system.

GAU-8 Avenger

If there is a pyramid of badassery when it comes to guns, the GAU-8 Avenger, carried by the A-10 Thunderbolt II (“Warthog”) close air support aircraft, is near the pinnacle. Explore the details of this bad boy.

Rocket Science

Rocket engineering is complicated and demanding, but rocket science is pretty straightforward. Explore the rocket equation, which governs the operation of all rockets, and understand why it's so difficult to get to orbit from the surface of the Earth and why multistage rockets make sense.

The Army's Flying Saucer

In the late 1950s, the U.S. Army investigated a flying saucer as an airborne replacement for the ubiquitous Jeep. This is the story of the Avro Canada VZ-9 Avrocar, one of the most curious projects of the “anything goes” era of aviation.

Slide Rule

Before computers and calculators, there were slide rules. It is difficult for people today to appreciate just how magic it was to be able to carry a small tool, made of bamboo and plastic, that could perform many of the computations of engineering and science which used to be so tedious in mere seconds, as long as you were happy with its limited precision. This document explores this vintage computing tool, using it to solve a variety of problems ranging from loading a turnip truck to interstellar flight.

Frisky Molecules

Essays about a variety of highly reactive and/or explosive molecules. Don't try this at home.

Clash of Ideologies: Communism, Islam, and the West

Western politicians say, “We're not at war with Islam.” But Islam is more than a just a religion. Its scriptures specify a political system, civil and criminal law, economics and trade, laws of war, and other matters which other major religions leave to civil authority, and some of these policy prescriptions conflict with Western values. This essay explores whether the West should treat these aspects of Islam as an ideology, like communism, fundamentally incompatible with its values, and how best to confront it.

Islam and Political Freedom

Is Islam compatible with political freedom? This document combines data from the Pew Research Center and Freedom House to investigate how empirical evidence addresses this question.