A (Card) Table-Top Turing Machine Of Magic: The Gathering Cards

July 18, 2019 by Roger Cheng 8 Comments

Within normal rules of collectible card game Magic: The Gathering a player may find themselves constrained to only a single legal course of action forward. It’s a situation players could craft to frustrate their opponents, though the victims usually break free after a few moves. But under a carefully crafted scenario, players would have no choice but to become the execution engine for a Turing-complete programming language written with Magic cards via techniques detailed in this paper.

One of the authors of this paper, [Alex Churchill], started working on this challenge in 2010. We covered an earlier iteration of his work here, and his own criticism that it was dependent on player cooperation. At various points, the game rules state a player “may” take certain actions and the construct falls apart if our player chooses the wrong thing. It would be as if a computer was built out of transistors that “may” switch as commanded or not, which would not be a very reliable method of computation.

To improve reliability of this particular Turing machine execution engine, the team combed through rules and cards to devise an encoding where the player is only ever presented with a single legal course forward. This ensures deterministic execution of the instruction stream, and now with proof of Turing-completeness in hand, we congratulate [Alex] on a successful conclusion to his decade-long quest.

We have a primer available for anyone who wants a refresher on Turing machines. They are utterly impractical but fun for hackers to build, and they are typically constructed of electronics and LEDs instead of ink on cardboard.

Via Ars Technica, who have presented their own analysis of this machine.

Main image: Unspecified set of Magic: The Gathering cards by [Robert] CC BY 2.0

Tic-Tac-Toe, In TTL

June 29, 2019 by Jenny List 15 Comments

We’ll all be familiar with Tic-Tac-Toe, or Noughts and Crosses, a childhood pencil-and-paper diversion which has formed the basis of many a coding exercise. It’s an easy enough task to implement in software, but how many of us have seen it done in hardware alone? That’s just what [Warren Toomey] has done using TTL chips, and his method makes for a surprisingly simple circuit.

At its heart is an 8 kB ROM that contains precomputed move sequences that are selected via an address composed of the game states for both player and machine. A series of flip-flops control and buttons to make the board, and a 555 provides a clock.

The technique of using a ROM to replace complex logic is a very powerful one that is facilitated by the low price of relatively large devices that would once have been unaffordable. We’ve seen the technique used elsewhere, including as an ALU in a TTL CPU, and even for an entire CPU in its own right.

You can see the result in operation in the video below the break, and should you wish to have a go for yourself all the relevant information can be found in a GitHub repository.

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This Upgraded Power Wheels Toy Is Powerful Enough To Need Traction Control

June 23, 2019 by Jenny List 17 Comments

A Lamborghini Aventador Is beyond the budget of all but the most well-heeled fathers, but [CodeMakesItGo] came pretty close with a gift for his young son. It was a Lamborghini Aventador all right, but only the 6V Power Wheels ride-on version. As such it was laclustre even for a youngster in its performance, so he decided to give it a 12V upgrade. This proved to have enough grunt to cause wheelspin on those hard plastic wheels, so a further upgrade was a traction control system featuring a NodeMCU. No other child has such a conveyance!

Veterans of the Power Racing Series or Hacky Racers might have expected to see a Chinese motor controller in the mix, but instead he’s used a set of relays for simple on-off control. The traction control has a pair of 3D-printed sensor wheels that operate upon a corresponding pair of optocouplers to provide feedback to the NodeMCU. A set of different drive options were tried, with finally an H-bridge board being found to be most reliable.

The video below the break shows the hardware, and goes into some detail on the software. The NodeMCU’s WiFi is used to provide some tweakability to the system on the go. The traction control turns out to lower the standing start speed a little, but makes the machine more controllable by its driver. he certainly seems happy with his toy!

Long-time readers will know this isn’t the first Power Wheels upgrade we’ve shown you.

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Coffee Tables, Computers, And Railways

June 22, 2019 by Jenny List 22 Comments

If you were a British kid at any time from the 1950s to the 1980s, the chances are that your toy shop had a train set in it. Not just any train set, but a full model railway layout in a glass case roughly the size of a pool table, with a button that when pressed started a timer and set a little tank engine off on a circuit with a pair of coaches. Magical for a generation raised on black-and-white TV, but probably not something that would cut it with today’s youth. A modern take on the glass-case layout comes from [Jack Flynn], who has created a coffee table with an automated and computerised N-gauge railway layout inside it. And this is definitely a railway rather than a railroad, the main locomotive is a Brush Type 4, a British Rail Class 47 diesel.

The modelling is a work of art, with a slightly idealised British street scene in an oval of double track against a backdrop of a rocky hillside. In the hill is an unexpected surprise which you can see on the video we’ve placed below the break, and beneath it lie the electronics. A Teensy handles the track switching and all the various LED lights around the board, a Sprog DCC controller takes care of the trains, and overseeing everything is a Raspberry Pi running some custom software in Python with a web interface for control. We probably wouldn’t be able to resist a bit of remote-control railway action if our coffee table had a layout like this one!

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Automated Dice Tester Uses Machine Vision To Ensure A Fair Game

June 20, 2019 by Dan Maloney 8 Comments

People take their tabletop games very, very seriously. [Andrew Lauritzen], though, has gone far above and beyond in pursuit of a fair game. The game in question is Star War: X-Wing, a strategy wargame where miniature pieces are moved according to rolls of the dice. [Andrew] suspected that commercially available dice were skewing the game, and the automated machine-vision dice tester shown in the video after the break was the result.

The rig is a very clever design that maximizes the data set with as little motion as possible. The test chamber is a box with clear ends that can be flipped end-for-end by a motor; walls separate the chamber into four channels to test multiple dice on each throw, and baffles within the channels assure randomization. A webcam is positioned below the chamber to take a snapshot of each “throw”, which is then analyzed in OpenCV. This scheme has the unfortunate effect of looking at the dice from the table’s perspective, but [Andrew] dealt with that in true hacker fashion: he ignored it since it didn’t impact the statistics he was interested in.

And speaking of statistics, he generated a LOT of them. The 62-page report of results from his study is an impressive piece of work, which basically concludes that the dice aren’t fair due to manufacturing variability, and that players could use this fact to cheat. He recommends pooled sets of dice to eliminate advantages during competitive play.

This isn’t the first automated dice roller we’ve seen around these parts. There was the tweeting dice-bot, the Dice-O-Matic, and all manner of electronic dice throwers. This one goes the extra mile to keep things fair, and we appreciate that.

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Lego Goes Underwater, With Model Submarines And Missiles

June 8, 2019 by Al Williams 7 Comments

It is fun to make a toy vehicle with Lego, but it is even more fun to make one that actually works. [PeterSripol] made two Lego submarines, and you can see them in the video below. There isn’t a lot of build information, but watching the subs fire missiles and then getting destroyed by depth charges is worth something.

One of the subs is larger and uses a rudder to steer. It was apparently harder to control than the other smaller sub which used two motors thrusting opposite one another to steer. Looks like fun.

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Circuit Bending Those Adorable Voices

June 8, 2019 by Mike Szczys 8 Comments

Leapfrog make some pretty awesome kids electronics. Especially admirable is the low cost, the battery life, and the audio quality of these devices. This circuit bending hack takes advantage of those audio circuits by turning the Alphabet Pal into your lead vocalist. The performance in the demo video begins with some impressive tricks, but just wait for it because by the end the little purple caterpillar proves itself an instrument worthy of a position beside that fancy Eurorack you’ve been assembling.

The image above provides a great look inside the beastie. [Jason Hotchkiss] mentions he’s impressed by the build quality, and we have to agree. Plus, look at all of those inputs — this is begging to leave toyland and join the band. With an intuitive sense that can only be gained through lots of circuit-bending experience, he guessed that the single through-hole resistor on the PCB was used to dial in the clock speed. That made it easy to throw in a trimpot for pitch-bending and he moved on to figure out individual note control.

All of those caterpillar feet are arranged in a keyboard matrix to detect button presses. After pulling out the oscilloscope for a bit of reverse engineering, [Jason] grabbed a PIC microcontroller and added it to the same solder points as the stock ribbon connector. The result is that the buttons on the feet still work, but now the Alphabet Pal also has MIDI control.

Take a look at the writeup for full details, and the video after the break to hear it in action. If you’re a fan of circuit-bent toys, this pretty pink keyboard hack always impressed us, especially the spring reverb that was added!

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