The Lambda Papers: When LISP Got Turned Into A Microprocessor

October 20, 2025 by Maya Posch 7 Comments

The physical layout of the SCHEME-78 LISP-based microprocessor by Steele and Sussman. (Source: ACM, Vol 23, Issue 11, 1980)

During the AI research boom of the 1970s, the LISP language – from LISt Processor – saw a major surge in use and development, including many dialects being developed. One of these dialects was Scheme, developed by [Guy L. Steele] and [Gerald Jay Sussman], who wrote a number of articles that were published by the Massachusetts Institute of Technology (MIT) AI Lab as part of the AI Memos. This subset, called the Lambda Papers, cover the ideas from both men about lambda calculus, its application with LISP and ultimately the 1980 paper on the design of a LISP-based microprocessor.

Scheme is notable here because it influenced the development of what would be standardized in 1994 as Common Lisp, which is what can be called ‘modern Lisp’. The idea of creating dedicated LISP machines was not a new one, driven by the processing requirements of AI systems. The mismatch between the S-expressions of LISP and the typical way that assembly uses the CPUs of the era led to the development of CPUs with dedicated hardware support for LISP.

The design described by [Steele] and [Sussman] in their 1980 paper, as featured in the Communications of the ACM, features an instruction set architecture (ISA) that matches the LISP language more closely. As described, it is effectively a hardware-based LISP interpreter, implemented in a VLSI chip, called the SCHEME-78. By moving as much as possible into hardware, obviously performance is much improved. This is somewhat like how today’s AI boom is based around dedicated vector processors that excel at inference, unlike generic CPUs.

During the 1980s LISP machines began to integrate more and more hardware features, with the Symbolics and LMI systems featuring heavily. Later these systems also began to be marketed towards non-AI uses like 3D modelling and computer graphics. As however funding for AI research dried up and commodity hardware began to outpace specialized processors, so too did these systems vanish.

Top image: Symbolics 3620 and LMI Lambda Lisp machines (Credit: Jason Riedy)

Word Processing: Heavy Metal Style

October 20, 2025 by Al Williams 11 Comments

If you want to print, say, a book, you probably will type it into a word processor. Someone else will take your file and produce pages on a printer. Your words will directly turn on a laser beam or something to directly put words on paper. But for a long time, printing meant creating some physical representation of what you wanted to print that could stamp an imprint on a piece of paper.

The process of carving something out of wood or some other material to stamp out printing is very old. But the revolution was when the Chinese and, later, Europeans, realized it would be more flexible to make symbols that you could assemble texts from. Moveable type. The ability to mass-produce books and other written material had a huge influence on society.

But there is one problem. A book might have hundreds of pages, and each page has hundreds of letters. Someone has to find the right letters, put them together in the right order, and bind them together in a printing press’ chase so it can produce the page in question. Then you have to take it apart again to make more pages. Well, if you have enough type, you might not have to take it apart right away, but eventually you will.

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Site Of Secret 1950s Cold War Iceworm Project Rediscovered

October 17, 2025 by Maya Posch 7 Comments

The overall theme of the early part of the Cold War was that of subterfuge — with scientific missions often providing excellent cover for placing missiles right on the USSR’s doorstep. Recently NASA rediscovered Camp Century, while testing a airplane-based synthetic aperture radar instrument (UAVSAR) over Greenland. Although established on the surface in 1959 as a polar research site, and actually producing good science from e.g. ice core samples, beneath this benign surface was the secretive Project Iceworm.

By 1967 the base was forced to be abandoned due to shifting ice caps, which would eventually bury the site under over 30 meters of ice. Before that, the scientists would test out the PM-2A small modular reactor. It not only provided 2 MW of electrical power and heat to the base, but was itself subjected to various experiments. Alongside this public face, Project Iceworm sought to set up a network of mobile nuclear missile launch sites for Minuteman missiles. These would be located below the ice sheet, capable of surviving a first strike scenario by the USSR. A lack of Danish permission, among other complications, led to the project eventually being abandoned.

It was this base that popped up during the NASA scan of the ice bed. Although it was thought that the crushed remains would be safely entombed, it’s estimated that by the year 2100 global warming will have led to the site being exposed again, including the thousands of liters of diesel and tons of hazardous waste that were left behind back in 1967. The positive news here is probably that with this SAR instrument we can keep much better tabs on the condition of the site as the ice cap continues to grind it into a fine paste.

Top image: Camp Century in happier times. (Source: US Army, Wikimedia)

A Tale Of Two Car Design Philosophies

October 16, 2025 by Bryan Cockfield 114 Comments

As a classic car enthusiast, my passion revolves around cars with a Made in West Germany stamp somewhere on them, partially because that phrase generally implied a reputation for mechanical honesty and engineering sanity. Air-cooled Volkswagens are my favorites, and in fact I wrote about these, and my own ’72 Super Beetle, almost a decade ago. The platform is incredibly versatile and hackable, not to mention inexpensive and repairable thanks to its design as a practical, affordable car originally meant for German families in the post-war era and which eventually spread worldwide. My other soft-spot is a car that might seem almost diametrically opposed to early VWs in its design philosophy: the Mercedes 300D. While it was a luxury vehicle, expensive and overbuilt in comparison to classic Volkswagens, the engineers’ design choices ultimately earned it a reputation as one of the most reliable cars ever made.

As much as I appreciate these classics, though, there’s almost nothing that could compel me to purchase a modern vehicle from either of these brands. The core reason is that both have essentially abandoned the design philosophies that made them famous in the first place. And while it’s no longer possible to buy anything stamped Made in West Germany for obvious reasons, even a modern car with a VIN starting with a W doesn’t carry that same weight anymore. It more likely marks a vehicle destined for a lease term rather than one meant to be repaired and driven for decades, like my Beetle or my 300D.

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Rubik’s WOWCube: What Really Makes A Toy?

October 15, 2025 by Maya Posch 20 Comments

If there ever was a toy that enjoys universal appeal and recognition, the humble Rubik’s Cube definitely is on the list. Invented in 1974 by sculptor and professor of architecture Ernő Rubik with originally the name of Magic Cube, it features a three-by-three grid of colored surfaces and an internal mechanism which allows for each of these individual sections of each cube face to be moved to any other face. This makes the goal of returning each face to its original single color into a challenge, one which has both intrigued and vexed many generations over the decades. Maybe you’ve seen one?

Although there have been some variations of the basic 3×3 grid cube design over the years, none have been as controversial as the recently introduced WOWCube. Not only does this feature a measly 2×2 grid on each face, each part of the grid is also a display that is intended to be used alongside an internal processor and motion sensors for digital games. After spending many years in development, the Rubik’s WOWCube recently went up for sale at $299, raising many questions about what market it’s really targeting.

Is the WOWCube a ‘real’ Rubik’s Cube, and what makes something into a memorable toy and what into a mere novelty gadget that is forgotten by the next year like a plague of fidget spinners?

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The Great Northeast Blackout Of 1965

October 14, 2025 by Dan Maloney 31 Comments

At 5:20 PM on November 9, 1965, the Tuesday rush hour was in full bloom outside the studios of WABC in Manhattan’s Upper West Side. The drive-time DJ was Big Dan Ingram, who had just dropped the needle on Jonathan King’s “Everyone’s Gone to the Moon.” To Dan’s trained ear, something was off about the sound, like the turntable speed was off — sometimes running at the usual speed, sometimes running slow. But being a pro, he carried on with his show, injecting practiced patter between ad reads and Top 40 songs, cracking a few jokes about the sound quality along the way.

Within a few minutes, with the studio cart machines now suffering a similar fate and the lights in the studio flickering, it became obvious that something was wrong. Big Dan and the rest of New York City were about to learn that they were on the tail end of a cascading wave of power outages that started minutes before at Niagara Falls before sweeping south and east. The warbling turntable and cartridge machines were just a leading indicator of what was to come, their synchronous motors keeping time with the ever-widening gyrations in power line frequency as grid operators scattered across six states and one Canadian province fought to keep the lights on.

They would fail, of course, with the result being 30 million people over 80,000 square miles (207,000 km²) plunged into darkness. The Great Northeast Blackout of 1965 was underway, and when it wrapped up a mere thirteen hours later, it left plenty of lessons about how to engineer a safe and reliable grid, lessons that still echo through the power engineering community 60 years later.

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Reshaping Eyeballs With Electricity, No Lasers Or Cutting Required

October 8, 2025 by Lewin Day 36 Comments

Glasses are perhaps the most non-invasive method of vision correction, followed by contact lenses. Each have their drawbacks though, and some seek more permanent solutions in the form of laser eye surgeries like LASIK, aiming to reshape their corneas for better visual clarity. However, these methods often involve cutting into the eye itself, and it hardly gets any more invasive than that.

A new surgical method could have benefits in this regard, allowing correction in a single procedure that requires no lasers and no surgical cutting of the eye itself. The idea is to use electricity to help reshape the eye back towards greater optical performance.

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