Calculating Pi On The 4004 CPU, Intel’s First Microprocessor

These days we are blessed with multicore 64-bit monster CPUs that can calculate an entire moon mission’s worth of instructions in the blink of an eye. Once upon a time, though, the state of the art was much less capable; Intel’s first microprocessor, the 4004, was built on a humble 4-bit architecture with limited instructions. [Mark] decided calculating pi on this platform would be a good challenge. 

It’s not the easiest thing to do; a 4-bit processor can’t easily store long numbers, and the 4004 doesn’t have any native floating point capability either. AND and XOR aren’t available, either, and there’s only 10,240 bits of RAM to play with. These limitations guided [Mark’s] choice of algorithm for calculating the only truly round number. Continue reading “Calculating Pi On The 4004 CPU, Intel’s First Microprocessor”

Javascript Is Everywhere. Even MSDOS

Although pundits have joked that Java’s “write once, run everywhere” slogan might be better expressed as “write once, debug everywhere,” a relative of Java — JavaScript — has delivered on both promises better than its namesake. Thanks to its proliferation in browsers, JavaScript is a veritable lingua franca of computer languages which has led to entire applications being written in it using tools like Node.js and Electron, and not just browsers. But what if you are still using MSDOS or Windows 98? We know some of you do, at least on retro machines. Don’t feel left out, the DOjS project has jSH, a JavaScript engine for DOS and related operating systems.

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2022 Sci-Fi Contest: A Friendly Wall Drawing Robot

Drawing on walls is fine for children, but adults tend to get bored quickly with such antics. Even more so when they realize who is responsible for cleaning up afterwards. Instead, consider delegating those duties to a friendly helper by the name of Fumik, as [engineer2you] has done.

Fumik, who looks like a cute little jellyfish, can draw pictures up to 5 meters wide and 3 meters high, making for a massive canvas. Powered by an Arduino Mega 2560 outfitted with a CNC shield, a pair of stepper motors drive pulleys with toothed belts to move Fumik to various positions along the wall. Another smaller stepper motor is used to drive the pen forwards and backwards as needed. Fumik can be programmed to trace out various designs in SVG format. These must be converted to code and programmed into the Arduino, at which point Fumik can begin work, drawing on the wall with its pen.

It’s a fun build, and based on photos shared by [engineer2you,] Fumik is quite able at drawing clean and neat designs without a lot of smudging or jagged lines. As a bonus, it’s easy to swap out the pen, so multicolored designs can be drawn in multiple passes.

We’ve seen other robot drawing builds before, too, like this capable portrait artist. Video after the break.

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Multicolor Drawbot Highlights Importance Of Limit Switches

Plotters and drawing robots are fun projects that let you create art with all the precision and perfection that computer numerical control can deliver. [TUENHIDIY] demonstrates that ably with the Multicolor DrawBot.

The build relies on a simple XY Cartesian design, using a pair of NEMA 17 stepper motors. It’s built in the typical CoreXY fashion, running GRBL firmware on an Arduino Uno.

Where [TUENHIDIY] gets creative is in the pen itself. Rather than using a simple ballpoint or marker, instead, a retractable multicolor pen is used instead. With the multicolor pen on board, [TUENHIDIY] notes the importance of limit switches in the design. These allow the the ‘bot to make multiple passes, each time in a different color, to build up a multicolor image. Without the limit switches in place, it would be impossible to line up each following pass.

We’d love to see the build taken even further with a servo-based system for switching colors automatically. As it is, though, [TUENHIDIY] has a capable plotter that can deliver tidy multicolor artworks.

One of the more curious applications of plotters of late are those used to send faux handwritten letters through the postal system.  Video after the break.

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2022 Sci-Fi Contest: Motorized AT-AT Walker Gets Around With Servos

The AT-AT Walker was one of the more fearsome weapons of the Star Wars universe, even if it was incredibly slow and vulnerable to getting tangled up in Rebel tow cables. However, you can build your own small-scale example using servos for propulsion, as [Luke J. Barker] ably demonstrates.

Taking off the outer shell reveals the servo motors driving the leg linkages.

The build is a remix of the motorized AT-AT from [LtDan] on Thingiverse, originally powered by a 90 rpm DC gearmotor. [Luke] remixed the design, setting it up to be driven by eight servomotors instead. They’re controlled from a SparkFun RedBoard Edge, an Arduino-compatible microcontroller board that fits rather neatly inside the AT-AT shell.

Programmed with a simple sine-wave walk cycle, the AT-AT ambles along in a ponderous manner. It’s altogether very much like the real fictitious thing, albeit without the scorching sizzle of blaster fire ringing out across a frozen plain.

Quadruped vehicles never really caught on for military use, but that’s not to say nobody ever tried. Video after the break.

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The 2022 Hackaday Prize Hack Chat Kicks Things Off

The 2022 Hackaday Prize is on, and we’ve already seen some incredible submissions by folks who believe their idea just might have what it takes to make the world a better place. But as with all contests, it’s good to understand all the rules before you get too involved. We promise nothing’s hidden in the fine print, but we certainly don’t fault anyone who wants to make sure.

Which is why Majenta Strongheart, Head of Design and Partnerships at our parent company Supplyframe, stopped by this week’s Hack Chat to answer any and all questions the community had about this global hardware design challenge. A lot of ground was covered in an hour, with Majenta making sure everyone’s questions and concerns were addressed to their satisfaction. After all, with a residency at the Supplyframe DesignLab and a total of $125,000 in prize money up for grabs, we want to make sure everyone’s got the facts straight.

So what burning questions did the Hackaday community have about this year’s Prize? Several people wanted to know more about the themes of sustainability, circularity, and climate crisis resiliency. For example, what exactly does circularity mean in this context? While Challenge #2 “Reuse, Recycle, Revamp” most clearly exemplifies the idea, Majenta explained that this time around the judges will be giving particular consideration to ideas that limit the extraction of raw materials and the production of waste.

For a practical example, 2022 Hackaday Prize judge James Newton pointed to the direct granule extruder designed by Norbert Heinz. The project, which took 5th place last year, allows waste plastic to easily be repurposed in a desktop 3D printer. This includes objects which the printer itself produced, but for whatever reason, are no longer desired or needed. This “life-cycle” for printed objects, wherein the same plastic can be printed over and over again into new objects, is a perfect encapsulation of circularity within the context of this year’s prize.

Others were looking for clarification on the contest rules. Specifically, there was some confusion about entering existing projects into the competition. Did it have to be a completely new idea? What if you’d already been working on the project for years, but had never shown it publicly before? Not to worry — existing projects can absolutely be entered into the 2022 Hackaday Prize. In fact, even if the project had already been entered into the Hackaday Prize previously, it’s still fair game.

But there is an important caveat: to be eligible for this year’s Prize, the project MUST be documented on a new Hackaday.io page. Additionally, if it’s a project that has previously been entered into a Hackaday contest, you’ll have to show that it is “significantly different from when previously entered and show meaningful development during the course of the Contest“, as stated in the official rules. In layman’s terms, it means that anyone who tries to submit and old and outdated Hackaday.io page into the competition will find their entry disqualified.

Towards the end of the Chat, Erin Kennedy, a Hackaday Prize veteran that readers may know better as “Erin RobotGrrl” brought up the subject of mentors. In previous years, hardware luminaries like Andrew “Bunnie” Huang and Mitch Altman were made available to offer advice and guidance to the individuals and teams behind the Prize entries. While very proud of this effort, Majenta explained that at least for now, Mentor Sessions are on hold until that aspect of the program can be retooled. The main issue is figuring out the logistics involved; planing video calls between several groups of busy folks is just as tricky as it sounds. That said, bringing the Mentor Sessions back for 2022 isn’t completely out of the question if there’s enough interest from the competitors.

We appreciate Majenta taking the time to directly answer questions from the community, and hope that those who had their questions or concerns addressed during the Chat will ultimately decide to toss their hat into the ring. With a worthy goal and plenty of opportunities to win, we sincerely want to see as many people as possible get their entries in before the October 16th deadline. If you’re ready to take the next step, head over to the Contest page and show us what you’ve got.


The Hack Chat is a weekly online chat session hosted by leading experts from all corners of the hardware hacking universe. It’s a great way for hackers connect in a fun and informal way, but if you can’t make it live, these overview posts as well as the transcripts posted to Hackaday.io make sure you don’t miss out.

Hackaday Podcast 164: Vintage NASA Soldering, Mouse Bites, ATTiny85 Graphics, And PVC Pontoons

Join Hackaday Editor-in-Chief Elliot Williams and Managing Editor Tom Nardi as they review the most interesting hacks and stories of the previous week. This time we’ll start things off by talking about the return of in-person events, and go over several major conventions and festivals that you should add to your calendar now. Then we’ll look at a NASA training film from the Space Race, an interesting radio-controlled quirk that Tesla has built into their cars for some reason, a very promising autonomous boat platform, and some high performance visuals generated by an ATtiny85. Stick around to find out what happens with an interplanetary probe looses its ride to space, and why the best new enclosure for your Raspberry Pi 4 might be a surveillance camera.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments below!

Direct Download

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