PS/2 Keyboard For Raspberry Pi

January 14, 2016 by Al Williams 29 Comments

A lot of people can bake a cake. Sort of. Most of us can bake a cake if we have a cake mix. Making a cake from scratch is a different proposition. Sure, you know it is possible, but in real life, most of us just get a box of cake mix. The Raspberry Pi isn’t a cake (or even a pie), but you could make the same observation about it. You know the Raspberry Pi is just an ARM computer, you could program it without running an available operating system, but realistically you won’t. This is what makes it fun to watch those that are taking on this challenge.

[Deater] is writing his own Pi operating system and he faced a daunting problem: keyboard input. Usually, you plug a USB keyboard into the Pi (or a hub connected to the Pi). But this only works because of the Linux USB stack and drivers exist. That’s a lot of code to get working just to get simple keyboard input working for testing and debugging. That’s why [Deater] created a PS/2 keyboard interface for the Pi.

Even if you aren’t writing your own OS, you might find it useful to use a PS/2 keyboard to free up a USB port, or maybe you want to connect that beautiful Model-M keyboard without a USB adapter. The PS/2 keyboard uses a relatively simple clock and data protocol that is well-understood. The only real issue is converting the 5V PS/2 signals to 3.3V for the Pi (and vice versa, of course).

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3D Printing Metal From Rust

January 14, 2016 by Elliot Williams 25 Comments

It seems backwards, but engineers from Northwestern University have made 3D printing metal easier (and eventually cheaper) by adding extra production steps to the procedure. (Paper available in PDF).

Laser sintering works by laying down a thin layer of metal powder and then hitting it with a strong enough laser to sinter the particles together. (Sintering sticks the grains together without getting the metal hot enough to melt it.) The rapid local heating and cooling required to build up 3D objects expands and cools the metal, and can result in stresses inside the resulting object.

The Northwestern team still lays down layers of powder, but glues the layers together with a quick-drying polymer instead of fusing them with a laser. Once the full model is printed, they then sinter it in one piece in an oven.

anewwaytopri_tn — 3D-printed copper lattice. Credit: Ramille Shah and David Dunand

The advantages of adding this extra step are higher printing speed — squirting the liquid out of syringe heads can be faster than fusing metal particles with a laser — and increased structural integrity because the whole model is heated and cooled at one time. A fringe benefit is that the model is still a bit flexible before firing, opening up possibilities for printing a flat model and then bending it into shape before sintering.

And if that weren’t enough, the team figured that they’d add a third step to the procedure to allow it to be used with rust (iron oxide) as the starting powder. They print the rust and polymer model, then un-rust the iron using hydrogen, and then fire it as before. Why rust? Do you know anything cheaper to use as a raw material?

What do you think? The basic idea may even be DIYable — glue metal particles together and heat them up enough to stick. Not in my microwave oven, though. We’d love to see a more energy-efficient 3D metal printer.

Thanks to [Joe] for the tip!

Decoding Data Hiding In Star Trek IV

January 13, 2016 by Adam Fabio 40 Comments

1986: The US and Russia signed arms agreements, Argentina won the world cup, and Star Trek IV: The Voyage Home hit the theaters. Trekkies and the general public alike enjoyed the film. Some astute hams though, noticed a strange phenomenon about halfway through the film. During a pivotal scene, Scotty attempts to beam Chekov and Uhura off the Enterprise, but has trouble with interference. The interference can be heard over the ubiquitous Star Trek comm link. To many it may sound like random radio noise. To the trained ear of a [Harold Price, NK6K] though, it sounded a heck of a lot like packet radio transmissions.

By 1989, the film was out on VHS and laser disc. With high quality audio available, [Harold] challenged his friend [Bob McGwier, N4HY] to decode the signal. [Bob] used the best computer he had available: His brain. He also had a bit of help from a Cray 2 supercomputer.

[Bob] didn’t own his own Cray 2 of course, this particular computer was property of the National Security Agency (NSA). He received permission to test Frequency Shift Keyed (FSK) decoder algorithms. Can you guess what his test dataset was?

The signal required a lot of cleanup: The original receiver was tuned 900 Hz below the transmission frequency. There also was a ton of noise. To make matters worse, Scotty kept speaking over the audio. Thankfully, AX.25 is a forgiving protocol. [Bob] persevered and was able to obtain some usable data. The signal turned out to be [Bill Harrigill, WA8ZCN] sending a Receive Ready (RR) packet to N6AEZ on 20 meters. An RR packet indicates that [Bill’s] station had received all previous packets and was ready for more. [Bob] called to [Bill], who was able to verify that it was probably him transmitting in the 1985 or 1986, around the time the sound editors would have been looking for effects.

That’s a pretty amazing accomplishment, especially considering it was 1989. Today, we carry supercomputers around in our pockets. The Cray 2 is roughly equivalent to an iPhone 4 in processing power. Modern laptop and desktop machines easily out class Seymour Cray’s machine. We also have software like GNU Radio, which is designed to decode data. Our challenge to you, the best readers in the world, is to replicate [Bob McGwier’s] work, and share your results.

Stallman’s One Mistake

January 13, 2016 by Brian Benchoff 147 Comments

We all owe [Richard Stallman] a large debt for his contributions to computing. With a career that began in MIT’s AI lab, [Stallman] was there for the creation of some of the most cutting edge technology of the time. He was there for some of the earliest Lisp machines, the birth of the Internet, and was a necessary contributor for Emacs, GCC, and was foundational in the creation of GPL, the license that made a toy OS from a Finnish CS student the most popular operating system on the planet. It’s not an exaggeration to say that without [Stallman], open source software wouldn’t exist.

Linux, Apache, PHP, Blender, Wikipedia and MySQL simply wouldn’t exist without open and permissive licenses, and we are all richer for [Stallman]’s insight that software should be free. Hardware, on the other hand, isn’t. Perhaps it was just a function of the time [Stallman] fomented his views, but until very recently open hardware has been a kludge of different licenses for different aspects of the design. Even in the most open devices, firmware uses GPLv3, hardware documentation uses the CERN license, and Creative Commons is sprinkled about various assets.

If [Stallman] made one mistake, it was his inability to anticipate everything would happen in hardware eventually. The first battle on this front was the Tivoization of hardware a decade ago, leading to the creation of GPLv3. Still, this license does not cover hardware, leading to an interesting thought experiment: what would it take to build a completely open source computer? Is it even possible?

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Finally, An Upgrade For The TI-86

January 13, 2016 by James Hobson 60 Comments

The eternal and everlasting TI-86 graphing calculator is a great calculator: first made back in 1997, and still used by students today. But its battery life kinda sucks. So [Dalius] decided to bring his TI-86 into the 21st century.

If you’re not familiar, the TI-86 runs off of 4 AAA batteries, preferably alkaline. If you use rechargeable NiMH they don’t last very long since they have a lower voltage per cell, which means it ends up draining even faster to a voltage level the TI-86 cannot operate at.

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Hackers And Heroes: Rise Of The CCC And Hackerspaces

January 12, 2016 by Elliot Williams 27 Comments

From its roots in phone phreaking to the crackdowns and legal precedents that drove hacking mostly underground (or into business), hacker culture in the United States has seen a lot over the last three decades. Perhaps the biggest standout is the L0pht, a visible 1990s US hackerspace that engaged in open disclosure and was, arguably, the last of the publicly influential US hacker groups.

The details of the American hacker scene were well covered in my article yesterday. It ended on a bit of a down note. The L0pht is long gone, and no other groups that I know of have matched their mix of social responsibility and public visibility. This is a shame because a lot of hacker-relevant issues are getting decided in the USA right now, and largely without our input.

Chaos Computer Club

But let’s turn away from the USA and catch up with Germany. In the early 1980s, in Germany as in America, there were many local computer clubs that were not much more than a monthly evening in a cafeteria or a science museum or (as was the case with the CCC) a newspaper office. Early computer enthusiasts traded know-how, and software, for free. At least in America, nothing was more formally arranged than was necessary to secure a meeting space: we all knew when to show up, so what more needed to be done?

Things are a little different in the German soul. Peer inside and you’ll find the “Vereinsmentalität” — a “club-mentality”. Most any hobby or sport that you can do in Germany has an associated club that you can join. Winter biathlon, bee-keeping, watercolor painting, or hacking: when Germans do fun stuff, they like to get organized and do fun stuff together.

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LUX Searches In The Deep For Dark Matter

January 12, 2016 by Mike Szczys 38 Comments

The Homestake Mine started yielding gold in 1876. If you had asked George Hearst, the operator at the time, if the mine would someday yield the secrets of the universe I bet he would have laughed you out of the room. But sure enough, by 1960 a laboratory deep in the mine started doing just that. Many experiments have been conducted there in the five and a half decades since. The Large Underground Xenon (LUX) experiment is one of them, and has been running is what is now called the Sanford Underground Research Facility (SURF) for about four years. LUX’s first round of data was collected in 2013, with the experiment and the rest of the data slated to conclude in 2016. The method, hardware, and results wrapped up in LUX are utterly fascinating.

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