Mauchly And Eckert’s Other Computers

August 14, 2026 by Al Williams No comments

If you ask a random person who [John Mauchly] or [J. Presper Eckert] were, you’d probably get a blank stare. Ask a Hackaday reader, and you have a better shot. People who know will tell you that the two were behind the famous ENIAC, which may or may not have been the first computer, but was certainly influential in kicking off the modern computer era. They worked at Penn, and now [Holly Mengel] of Penn’s Kislak Center for Special Collections, Rare Books, and Manuscripts wants to introduce us to the other computers they worked on after ENIAC.

We will admit that we knew about EDVAC and UNIVAC. But we’ll also confess we didn’t know about BINAC or Skeduflo, a computer in a rather large suitcase. BINAC can claim to be the first digital computer that was commercialized, although you could argue that since it was fairly limited and, reportedly, never worked after it was delivered. Supposedly, the customer disassembled it, shipped it to a secure facility, and hired a freshly graduated engineer to rebuild it, which didn’t go very well.

We couldn’t find much about Skeduflo, other than that it was a 75-pound analog computer made for critical path method (CPM) analysis. You set up the problem with a patchboard and potentiometers, and the result came out on an analog plotter. Those details are from a PMI interview with [Morgan Walker] and [Jim Kelley].

It makes sense that these inventors didn’t just finish off ENIAC and retire to a tropical island. While UNIVAC had a good bit of success and EDVAC was very influential, the others are arguably fairly obscure. UNIVAC even has a Disney connection.

Bladerunners And The Mother Of Invention

August 13, 2026 by Al Williams 20 Comments

There are plenty of stories about inventors who see a problem and decide they can do better. But Van Phillips had a little more motivation than most. The problem was his own leg. In 1976, Phillips was a 21-year-old college student when a water-skiing accident cost him his left leg below the knee. If that wasn’t bad enough, the prosthetic leg he received afterward wasn’t exactly a technological marvel. Prosthetic limbs of the era were generally designed to look and act something like a biological leg and foot, but “act” might be giving them too much credit. They were passive structures that provided something to stand on and roll over while walking.

Phillips wanted to do more than walk. There was just one problem: he wasn’t an engineer. Before the accident, he had been studying business. So, if he was going to build a better leg, first he was going to have to learn how.

Back To School

Traditional prosthetic feet (public domain)

Phillips became fascinated with prosthetics and eventually studied prosthetic design at Northwestern University’s Prosthetic-Orthotic Center. He also worked at the University of Utah’s prosthetics laboratory, where he had access to both the people and equipment he needed to experiment.

The conventional wisdom was that a prosthetic foot should imitate a human foot. That seems perfectly reasonable — evolution has had quite a long time to work on the design. But there’s a problem with simply copying the shape. A real foot isn’t just a foot-shaped object attached to the bottom of your leg. Muscles, tendons, and ligaments store and release energy as you walk or run. Your Achilles tendon, in particular, acts very much like a spring. A conventional prosthetic foot might look right, but it didn’t have anything corresponding to that spring.

Phillips eventually stopped worrying so much about making something that looked like a foot. Instead, he decided to make something that worked like one.

Continue reading “Bladerunners And The Mother Of Invention” →

Watch Today’s Eclipse At Home

August 12, 2026 by Al Williams 6 Comments

In a few hours, there is a solar eclipse that will be visible with a track that goes from Spain up through Greenland. Too late to travel for it, but thanks to [jonty], you can find all the webcams that will have a view.

This may be ideal. No funny glasses. No looking at a projected image on a card. Of course, many, if not all, of these cameras aren’t looking directly at the sun, so it isn’t clear if you’ll be able to see the actual eclipse or just the effect it has on the surroundings.

Continue reading “Watch Today’s Eclipse At Home” →

PC-1: The 1954 Computer With No Tubes, Relays, Or Transistors

August 11, 2026 by Al Williams 31 Comments

However you make a digital computer, you need something to represent a binary digit. Usually this is some form of switch: a relay, a tube, or a transistor, although there have been other ways to represent state. In 1954, [Eiichi Goto] of Japan invented the parametron, a resonant circuit using a ferrite core and a capacitor that could be moved between two phases.

According to [Goto’s] 1959 paper, the device is effectively a parametric oscillator, similar to some used at UHF frequencies by hams. The idea is that a tuned circuit is set to some frequency and driven with twice that frequency.

A What?

A parametron is essentially a resonant circuit made with inductors or capacitors whose reactance is varied at twice its resonant frequency. That “pumping” causes the circuit to oscillate at half the pump frequency. The neat trick is that there are two equally stable oscillation states at half the pump frequency, separated from each other by 180° of phase. Those two phases become binary 0 and 1. Depending on the incoming signals, one phase will win over the others.

Continue reading “PC-1: The 1954 Computer With No Tubes, Relays, Or Transistors” →

Linux Fu: Heads Or Tails For VPN

August 10, 2026 by Al Williams 6 Comments

If you’ve done much networking, you surely know the frustration of trying to connect to something, say a Raspberry Pi, that lives behind your consumer router. There are a number of solutions for this, ranging from opening ports on your router along with dynamic DNS. Or, you can operate a VPN server on your network. Modern Linux has a facility called Wireguard that lets you create secure network tunnels very easily, but it is a little difficult to set up. But there are tools like Tailscale that can do most of the work for you. There’s only one problem: Tailscale is sorta-kinda free, but not really. But it turns out, you can build your own Tailscale network, and it is easier than you might imagine.

In all fairness, Tailscale’s free tier is good and recently got even more generous, allowing unlimited nodes and up to six users. That’s plenty for most hackers. However, as we’ve seen before, what they can give they can also take away. Besides, there are some extra services you still have to pay for if you want them, but overall, the free tier is more than enough for most people.

On the other hand, no matter how great the free tier may be, some people don’t want to run things on other people’s hardware. Or you need that 7th user. Or you need paywalled features. No worries. Headscale is a self-hosted service that can do nearly everything the cloud portion of Tailscale does, and if you have a place to host it, you can be your own Tailscale server.

For the client side? That’s the best part. Headscale works seamlessly with the existing Tailscale clients. You simply have to point them to your server instead of the defaults.

Continue reading “Linux Fu: Heads Or Tails For VPN” →

Retrotechtacular: A View Of The Moon From 1964

August 9, 2026 by Al Williams 13 Comments

If you didn’t live through it, it is hard to understand how excited the general public was about the race for the moon. You can capture some of it by watching “Lunar Bridgehead,” a film about JPL monitoring the Ranger spacecraft as it hit, rather hard, on the lunar surface.

The Ranger program had been plagued with problems. The first five didn’t make it to the moon. Ranger 6 hit the moon, but failed to start its cameras. Ranger 7 was the first successful mission. There would be two more successful missions before the end of the program.

Continue reading “Retrotechtacular: A View Of The Moon From 1964” →

Tracking Bees With A Stereo Camera

August 8, 2026 by Al Williams 9 Comments

For whatever reason, [Jeremy] wants to photograph bees in flight. This is one of those things that doesn’t seem that hard until you try to do it. He’s got the mechanical part that can move the camera as fast as the bee flies. But you still have to point the camera correctly. He considered quite a few methods of acquiring and tracking the bee, but he finally settled on a stereo camera. His requirements also made the camera design challenging. In particular, the bees move fast enough that things like USB transmission times become significant. You can see his solution in the video below.

[Jeremy] does a great job explaining all the tradeoffs between frame rate, resolution, focal length, and other optical issues. Of course, he also wanted a global shutter sensor. Rolling shutter cameras scan row-by-row, creating the well-known “jello effect”. Global shutters capture all pixels at once. That also removes any uncertainty as to “when” the shutter fired.

Continue reading “Tracking Bees With A Stereo Camera” →