Debian Linux on a PowerMac 7200

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Those of us that run Linux on a modern or nearly-modern PC know that it’s a capable operating system.  It’s also (at least in my case with Ubuntu) extremely easy to install on a semi-modern computer. On a mid-90s era PowerMac 7200, things aren’t quite so simple.

In a testament to both his technical ability, and possibly even more so his tenacity, [Chris] was able to get Debian 6.07 running on a PowerMac destined for destruction. He had slated a few hours to upgrade this 56 Megabyte monster, but it turned out to be a several-day event. Those that are well-schooled in Linux may find the hairy details useful, and some more background can be found in part one. This project was a stepping-stone to something else, so we’re anxious to see what the end result is.

If you find this interesting, feel free to check out the retro edition of our site. It’s not entirely about ancient computers, but it can hopefully be displayed on one.

via [twitter]

Interpreting Brainf*#k on an AVR

brainfuck

We won’t call it useless, but we will ask why [Dan] wrote a brainfuck interpreter for the AVR

It’s not generating code for the AVR; think of it more as a bootloader. To run a brainfuck program, [Dan] uploads it to the EEPROM inside his ATMega32, after which the microcontroller takes over and starts performing whatever instruction the brainfuck program tells it to do. Because the whole thing runs off the EEPROM, the code size is limited to 1022 bytes. Enough for any brainfuck program written by a human, we think.

As for why [Dan] would want an AVR to build an interpreter for a language that is nearly unreadable by humans, we honestly have no idea other than the common, ‘because it’s there’ sentiment. There are some pretty cool projects out there that use brainfuck, including this genetic algorithm software developer. Right now, though, blinkey LEDs are enough to keep us happy, so you can see a video of brainfuck doing its thing on a LED bar display after the break.

[Read more...]

Automatic, custom Eagle schematics

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It’s a simple fact that for every circuit you design, someone else has done it before. If you’re working on a high altitude balloon project, there’s already a project out there with a microcontroller, barometric pressure sensor, and an SD card somewhere out there in a corner of the Internet. Google will only help so much if you want to copy these previous builds, which led [Ben] to come up with a better solution. He took dozens of building blocks for basic digital projects and put them all into one really great interface called HackEDA.

The premise is simple: most electronic projects are just electronic Lego. You connect your microcontroller to a sensor, add in a battery, throw in a few caps and resistors for good measure, and hopefully everything will work. HackEDA takes all those basic building blocks – microcontrollers, power sources, and sensors – and creates a custom Eagle schematic with all the parts your project needs

HackEDA is still very much in beta, so there aren’t a whole lot of building blocks to choose from. That said, being able to generate an Eagle schematic with all the parts necessary for your next project is a boon. With this, all you need for a final circuit board is to create a new board file, hit the autorouter, and spend a half hour fixing whatever mess the autorouter made.

Operation StratoSphere

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Panoramic photos are nice, however a full 360 degree x 180 degree, or spherical panorama would be even better. [Caleb Anderson] decided to take this concept much further, attempting to extract panoramic photos from video taken at 100,000 feet using a high-altitude balloon and six GoPro cameras.

The overview of this project can be found here, and gives some background. The first task was to start prototyping some payload containers, which for a device that you have little control over once out of your hands is quite critical. As well as some background, there’s a cool interactive panorama of the first test results on this page, so be sure to check it out.

The “real” hacking in this experiment wasn’t a matter of putting a balloon into the stratosphere or recovering it, however. Chaining these images together into pictures was a huge challenge, and involved a diverse set of skills and software knowledge that most of our readers would be proud to possess. There are several videos in the explanation, but we’ve embedded one with the cameras falling out of the sky. Be sure to at least watch until (or skip to) just after 1:05 where all the cameras impressively survive impact! [Read more...]

Web-based TI graphing calculator emulator

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You can leave the TI graphing calculator at home thanks to this web-based TI-83 and TI-84 emulator. As with pretty much all emulators, this depends on a ROM image from the actual hardware to work. But if you have one of the supported calculators (TI-83+, TI-83+ SE, TI-84+, or TI-84+SE) you can dump the image yourself and this should work like a charm.

[Christopher Mitchell] calls the project jsTIfied because he wrote it in JavaScript and HTML5 (that’s where the js comes from) and it’s based on the Texas Instruments line of hardware (hence the capital TI). After agreeing that you’re not getting any ROMs from his site you can choose the file to load on your browser. The image of the calculator has working buttons and will show the boot screen just like the real thing. You can use it like normal but you can load load up programs for the environment. See this demonstrated after the break.

We’ve seen some arguments online about the price of the TI line over the years. Prices haven’t dropped much over the decades even though they’re making pretty much the same hardware. It’s cool to see someone figure out how to emulate the hardware — and on a web interface to boot! But we’re left wondering why TI isn’t selling an equivalent app for iOS and Android or at least leveraging what must be millions in each production run for a lower retail price?

[Read more...]

How to write your own Minesweeper solver

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We think we have found project that will take over our holiday free time. [Bai Li] just published an excellent article about writing a program that can automatically solve the game of Minesweeper. For those of you who are unfamiliar, Minesweeper gives you a grid in which land mines have been randomly placed. As you click on boxes to reveal what is underneath you are greeted with a number which represents how many mines surround that box. [Bai's] project examines how the puzzle may be solved programmatically.

He chose to use Java to write the solver. This works well both reading from the screen as well as simulating mouse clicks on the game. The reading portion of the program uses color detection with a screenshot. There were two problems associated with this, the numeral one is almost the same color as an uncovered square, and the numerals seven and three use identical colors. The input portion was much simpler as he’s able to use the existing Robot class.

The logic behind writing an efficient solver is very interesting. One of the most fascinating examples is shown above. What should you do when there is no possible way to ensure a safe move? As with traditional chess games, [Bai] has the solver calculate all possible solutions and choose the move that has the best odds of success.

His source code is available, but won’t this one be fun to hack out from the concepts alone? For some reason this seems more accessible to us than something like the Bejeweled Blitz solver.

[Read more...]

Recording audio with Chrome using HTML5

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The Dubjoy project was stopped dead in its tracks when the newest version of the Google Chrome browser stopped using Adobe’s flash plugin and transitioned to their own called Pepper Flash. The aim of development was to produce a browser-based editor for translating the audio track of a video clip. After a bit of head scratching and a lot of research they decided to try ditching the use of Flash and implemented a way to record audio using HTML5.

There were quite a few issues along the way. The initial recording technique generated raw audio files, which are not playable by Chrome’s HTML5 audio player. This can be worked around by buffering the raw audio, then converting it to a different format once the recording is finished. The user also needs to monkey with the Chromes flags to enable HTML5 audio. So they did get it working, but it’s not yet a smooth process.

We love seeing the neat stuff you can do with HTML5. One of our favorites is the use of a tablet’s accelerometer as a browser game controller.

[via Reddit]

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