Hackaday Links: October 27, 2019

A year ago, we wrote about the discovery of treasure trove of original documentation from the development of the MOS 6502 by Jennifer Holdt-Winograd, daughter of the late Terry Holdt, the original program manager on the project. Now, Ms. Winograd has created a website to celebrate the 6502 and the team that built it. There’s an excellent introductory video with a few faces you might recognize, nostalgia galore with period photographs that show the improbable styles of the time, and of course the complete collection of lab notes, memos, and even resumes of the team members. If there were a microchip hall of fame – and there is – the 6502 would be a first-round pick, and it’s great to see the history from this time so lovingly preserved.

Speaking of the 6502, did you ever wonder what the pin labeled SO was for? Sure, the data sheets all say pin 38 of the original 40-pin DIP was the “Set Overflow” pin, an active low that set the overflow bit in the Processor Status Register. But Rod Orgill, one of the original design engineers on the 6502, told a different story: that “SO” was the initials of his beloved dog Sam Orgill. The story may be apocryphal, but it’s a Good Doggo story, so we don’t care.

You may recall a story we ran not too long ago about the shortage of plutonium-238 to power the radioisotope thermoelectric generators (RTGs) for deep-space missions. The Cold War-era stockpiles of Pu-238 were running out, but Oak Ridge National Laboratory scientists and engineers came up with a way to improve production. Now there’s a video showing off the new automated process from the Periodic Videos series, hosted by the improbably coiffed Sir Martyn Poliakoff. It’s fascinating stuff, especially seeing workers separated from the plutonium by hot-cells with windows that are 4-1/2 feet (1.4 meters) thick.

Dave Murray, better known as YouTube’s “The 8-Bit Guy”, can neither confirm nor deny the degree to which he participated in the golden age of phone phreaking. But this video of his phreaking presentation at the Portland Retro Gaming Expo reveals a lot of suspiciously detailed knowledge about the topic. The talk starts at 4:15 or so and is a nice summary of blue boxes, DTMF hacks, war dialing, and all the ways we curious kids may or may not have kept our idle hands busy before the Interwebz came along.

Do you enjoy a puzzle? We sure do, and one was just laid before us by a tipster who prefers to stay anonymous, but for whom we can vouch as a solid member of the hacker community. So no malfeasance will befall you by checking out the first clue, a somewhat creepy found footage-esque video with freaky sound effects, whirling clocks, and a masked figure reading off strings of numbers in a synthesized voice. Apparently, these clues will let you into a companion website. We worked on it for a bit and have a few ideas about how to crack this code, but we don’t want to give anything away. Or more likely, mislead anyone.

And finally, if there’s a better way to celebrate the Spooky Season than to model predictions on how humanity would fare against a vampire uprising, we can’t think of one. Dominik Czernia developed the Vampire Apocalypse Calculator to help you decide when and if to panic in the face of an uprising of the undead metabolically ambiguous. It supports several models of vampiric transmission, taken from the canons of popular genres from literature, film, and television. The Stoker-King model makes it highly likely that vampires would replace humans in short order, while the Harris-Meyer-Kostova model of sexy, young vampires is humanity’s best bet except for having to live alongside sparkly, lovesick vampires. Sadly, the calculator is silent on the Whedon model, but you can set up your own parameters to model a world with Buffy-type slayers at your leisure. Or even model the universe of The Walking Dead to see if it’s plausible that humans are still alive 3599 days into the zombie outbreak.

Plasma Globe Reveals Your Next Clue

If you like solving puzzles out in the real world, you’ve probably been to an escape room before, or are at least familiar with its concept of getting (voluntarily) locked inside a place and searching for clues that will eventually lead to a key or door lock combination that gets you out again. And while there are plenty of analog options available to implement this, the chances are you will come across more and more electronics-infused puzzles nowadays, especially if it fits the escape room’s theme itself. [Alastair Aitchison] likes to create such puzzles and recently discovered how he can utilize a USB powered plasma globe as a momentary switch in one of his installations.

The concept is pretty straightforward, [Alastair] noticed the plasma globe will draw significantly more current when it’s being touched compared to its idle state, which he measures using an INA219 current shunt connected to an Arduino. As a demo setup in his video, he uses two globes that will trigger a linear actuator when touched at the same time, making it an ideal multiplayer installation. Whether the amount of fingers, their position on the globe, or movement make enough of a reliable difference in the current consumption to implement a more-dimensional switch is unfortunately not clear, but definitely something worth experimenting with.

In case you’re planning to build your own escape room and are going for the Mad Scientist Laboratory theme, you’ll obviously need at least one of those plasma globes sparking in a corner anyway, so this will definitely come in handy — maybe even accompanied by something slightly larger? And for all other themes, you can always resort to an RFID-based solution instead.

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A Compiler In Plain Text Also Plays Music

As a layperson reading about some branches of mathematics, it often seems like mathematicians are just people who really like to create and solve puzzles. And, knowing that computer science shares a lot of its fundamentals with mathematics, we can assume that most computer scientists are also puzzle-solvers as well. This latest project from [tom7] shows off his puzzle creating and solving skills with a readable file which is also a paper, which is also a compiler for C programs, which can also play music.

[tom7] started off with the instruction set for the Intel 8086 processor. Of the instructions available, he wanted to use only instructions which are also readable in a text file. This limits him dramatically in what this file will be able to execute, but also sets up the puzzle. He walks through each of the hurdles he found by only using instructions that also code to text, including limited memory space, no obvious way of exiting the program once it was complete, not being able to jump backward in the program (i.e. looping), and a flurry of other issues that come up once the instruction set is limited in this way.

The result is a sort of C compiler which might not be the most efficient way of executing programs, but it sure is the most effective way of showing off [tom7]’s PhD in computer science. As a bonus, the file can also play an antiquated type of sound file due to one of the available instructions being a call for the processor to interact with I/O. If you want to learn a little bit more about compilers, you can check out a primer we have for investigating some of their features.

Thanks to [Greg] for the tip!

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An Enigma Wrapped In A Riddle Wrapped In A Vintage Radio

Puzzle boxes are great opportunities for hacking. You can start with a box which was originally used for something else. You get to design circuitry and controls which offer a complex puzzle for the players. And you can come up with a spectacular reward for those who solve it. [thomas.meston’s] Dr. Hallard’s Dream Transmission Box, which he created for an original party game, has all those elements.

The box was a broken 1948 National NC-33 Ham Radio purchased on eBay after a number of failed bids. Most of it was removed except for the speaker. The electronics is Arduino based, so most of the smarts are in the form of code. Potentiometers and a switch provide the mechanism for players to enter codes. And when the correct code is entered, a relay triggers an external smoke machine and turns on a laser which illuminates a party ball, rewarding the victors. And of course, there are also sound effects as well as a recorded message.

We weren’t kidding when we said puzzle boxes make great hacks. Here’s one which ignites fireworks, one made only from discrete components, and a valentine based one which makes your significant other work for their gift.

Solving A Rubik’s Cube With Just Two Motors

We’ve all seen videos of Rubik’s cube champions who can solve the puzzle in less than 5 seconds. And there are cube-twisting robots that can solve the cube even faster, often in under a second. This Rubik’s cube solver is not one of those robots, but it’s still pretty cool.

The reason we like Dexter Industries’ “BricKuber” is not for its lightning speed — it takes a minute or two to solve the puzzle. What we like is the simplicity of the approach to manipulating the cube. Built from LEGO parts, including Mindstorms motors and a BrickPi controller, the BricKuber uses only two motors to work the cube. One motor powers a square turntable upon which the cube sits, while the other powers an arm that does double duty — it either clamps the cube so the turntable can rotate a layer, or it rakes the cube to flip it 90° on the turntable. With a Pi Cam overhead, the rig images all six faces, calculates a solution to the cube, and then flips and twists the cube to solve it. It’s simultaneously mind-boggling and strangely relaxing to watch.

All the code is open source, and we strongly suspect a similar and possibly faster robot could be built without the LEGO parts. You might even be able to build one with popsicle sticks and an Arduino.

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Making The Best Plywood For Laser Cut Puzzles

Plywood laser-cuts fairly well but has drawbacks when used in serious production runs, as [Marie] explains in a blog post about a quest for the ultimate laser-cutting plywood. One of the things [Nervous System] makes and sells is generative jigsaw puzzles, and they shared their experience with the challenges in producing them. The biggest issue was the wood itself. They ended up getting a custom plywood made to fit their exact needs, a process that turned out neither as complex nor as unusual as it may sound.

An example of how a dense knot hidden in one of the plywood layers caused the laser to not cut all the way through.

Plywood is great because it’s readily available, but there are some drawbacks that cause problems when trying to do serious production of laser-cut plywood pieces. Laser cutting works best when the material being cut is consistent, but there can be areas of inconsistent density in plywood. If the laser encounters an unexpected knot somewhere in the wood, there is no way to slow down or to increase power to compensate. The result is a small area where the laser perhaps doesn’t quite make it through. A picture of an example from my workshop shows what this looks like.

When doing basic project work or prototyping, this kind of issue is inconvenient but usually some trimming and sanding will sort things out. When doing a production run for puzzles like [Nervous System] was doing, the issue is more serious:

  1. A jigsaw puzzle with a large number of cuts in a relatively small area has a higher chance of running into any problem spots in the material. If they exist, the laser will probably encounter them.
  2. Trouble spots in plywood can be on the inside layers, meaning they can’t be detected visually and are only discovered after they cause an incomplete cut.
  3. Increasing laser power for the whole job is an incomplete solution, as excessive laser power tends to make the cuts uglier due to increased scorching and charring.
  4. An inspection process becomes needed to check each puzzle piece for problems, which adds time and effort.
  5. A puzzle that had even one piece that did not cut properly will probably be scrapped because rework is not practical. That material (and any time and money that went into getting the nice artwork onto it) becomes waste.

Plywood is great stuff and can look gorgeous, but [Marie] says they struggled with its issues for a long time and eventually realized they had gone as far as they could with off-the-shelf plywoods, even specialty ones. They knew exactly what they needed, and it was time for something custom-made to serve those specific needs.

Having your own plywood custom-made may sound a little extreme, but [Marie] assures us it’s not particularly difficult or unreasonable. They contacted a small manufacturer who specialized in custom aircraft plywoods and was able to provide their laser-cut plywood holy grail: a 3-ply sheet, with high quality basswood core with birch veneers, and a melamine-based glue. It cuts better than anything else they have used, and [Marie] says that after four years they had certainly tried just about everything.

Your Puzzle’s Done When The Electronics Says So

We can race against the clock when assembling jigsaw puzzles online but what about competing against each other in the real world? [HomeMadeGarbage] came up with the simplest of solutions with his jigsaw puzzle timer that stops only when the puzzle’s completely assembled.

Copper strip on back of puzzle
Copper strip on back of puzzle

His simple solution was to attach copper foil tape to the back of the pieces, with overlap. He did this in a serpentine pattern to ensure that all pieces had a strip of the tape. The puzzle he used comes with a special container to assemble it in. At two corners of that container, he put two more pieces of copper foil, to which he soldered wires. Those two act as a switch. Only when the puzzle is completed will those two pieces be connected through the serpentine strip on the back of the puzzle.

Next, he needed a timer. The two wires from the puzzle container go to an Arduino UNO which uses an ILI9325 touch panel TFT display for both the start, stop, and reset buttons, and to show the time elapsed. Press the touch screen when it says START and begin assembling the puzzle. When the last piece is inserted, the serpentine strip of copper tape completes the circuit and only then does the Arduino program stop the timer. As you can see from the video below, the result makes doing the puzzle lots of fun.

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