Raspberry Pi Ain’t Afraid Of No Spectre And Will Not Meltdown

January 9, 2018 by Roger Cheng 43 Comments

While there’s broad agreement that Meltdown and Spectre attacks are really bad news at a fundamental level, there is disagreement on its immediate practical impact in the real world. Despite reassurance that no attacks have been detected in the wild and there’s time to roll out the full spectrum of mitigation, some want to find protection right now. If you’re interested in an usable and easy to set up modern desktop that’s free of Meltdown or Spectre threats, a Raspberry Pi can provide the immunity you seek.

[Eben Upton] explained the side channel attacks using fragments of Python for illustration, which was an enlightening read independent of the Raspberry Pi pitch. While these ARM cores perform speculative instruction fetches, they don’t speculatively execute them or modify the cache. Under the current circumstances, that makes all the difference in the world.

A clever security researcher may yet find a way to exploit speculative fetches in the future, and claiming that Raspberry Pi has superior security would be a stretch. The platform has its own set of security problems, but today Meltdown/Spectre is not among them. And that just might be enough to sway some decisions.

If you need to stay in the x86 world, look over what it’d take to to rewind back to an Intel 486.

Thanks to [D00med] for sharing the link in a comment to our overview article.

Improved Perfboard For Surface Mount Parts

January 9, 2018 by Brian Benchoff 26 Comments

Look through the last two decades of electronics project built on perfboard, and you’ll notice a trend. Perfboard is designed for through-hole parts, but ever more frequently, the parts we need are only available as surface mount devices. What does this mean for the future of all those protoboard, veroboard, and tagboard designs? It’s not good, but fortunately, there may be an answer. It’s perfboard designed for mounting SOICs, SOTs, and other surface mount devices.

Perfboard is an extremely simple concept. Most through-hole electronic components are built around 0.1″ or 2.54 mm spacing between pins. Yes, there are exceptions, but you can always bend the middle pin of a transistor and put it in a hole. SMT devices are different. You can’t really bend the pins, and the pin pitch is too small for the 0.1″ holes in traditional perfboard.

[electronic_eel] is changing that game up with his own design for perfboard. This perfboard has the traditional 0.1″ holes, but there are SMD pads sprinkled about between these holes. The result is being able to solder SOIC, SOT23-6, SOT23 and SOT363 devices directly to a board alongside 0603 and 0805 devices. Connect everything with a few beads of solder and you have a functional circuit made out of surface mount devices on something that’s still compatible with the old protoboard designs.

This isn’t the first time we’ve seen a new type of protoboard make it into production. A few years ago, Perf+, a bizarre ‘bus-based’ protoboard solution came onto the scene, although that wasn’t really designed for SMD parts. While [electronic_eel] doesn’t have any plans to sell his protoboard, the files are available, and you can easily design your own small piece of perfboard.

Eight SEGAs Singing

January 8, 2018 by Lewin Day 22 Comments

Way back in the dark ages, before the average computer could play back high quality recorded audio, things were done differently. Music and sounds were stored as instructions to be played back on audio synthesis chips, built into the computers and consoles of the 80s and 90s. These chips and their unique voices hold a special nostalgia that’s key to this era, making them popular to experiment with today. To that end, [little-scale] decided to wire up eight chips from the SEGA Master System to please your ears.

The chips, laid out on a breadboard with a Teensy LC running the show.

The chip in question is the SN76489, which we’ve also noted is used in the Sega Genesis as well. It packs 3 square wave tone generators, and a noise channel as well. With eight of these to play with, that’s 32 total channels. To drive these, [little-scale] decided to go the MIDI route. To get around the MIDI limit of 16 channels, he decided to split the frequency range in half. Each MIDI channel addresses two SN76489 channels, the top pitches being used for one, the lower pitches being used for the other. All this MIDI data is passed to a Teensy LC, which handles transposition of the note data to get everything back in tune, and addresses the eight chips to create a beautiful square wave symphony.

It’s a great way to create a cacophony of sound in a delightful vintage way, and code is available if you’d like to recreate the feat. What we’d like to know is this – what’s your favourite sound chip from yesteryear, and how badly do you want eight of them to sing in glorious harmony? Continue reading “Eight SEGAs Singing” →

AI Prosthesis Is Music To Our Ears

January 8, 2018 by Lewin Day 12 Comments

Prostheses are a great help to those who have lost limbs, or who never had them in the first place. Over the past few decades there has been a great deal of research done to make these essential devices more useful, creating prostheses that are capable of movement and more accurately recreating the functions of human body parts. At Georgia Tech, they’re working on just that, with the help of AI.

[Jason Barnes] lost his arm in a work accident, which prevented him from playing the piano the way he used to. The researchers at Georgia Tech worked with him, eventually producing a prosthetic arm that, unlike most, actually has individual finger control. This is achieved through the use of an ultrasound probe, which is used to detect muscle movements elsewhere on his body, with enough detail to allow the control of individual fingers. This is done through a TensorFlow-based neural network which analyses the ultrasound data to determine which finger the user is trying to move. The use of ultrasound was the major breakthrough which made this possible; previous projects have often relied on electromyogram sensors to read muscle impulses but these lack the resolution required.

The prosthesis is nicknamed the “Skywalker arm”, after its similarities to the prostheses seen in the Star Wars films. It’s not [Jason]’s first advanced prosthetic, either – Georgia Tech has also equipped him with an advanced drumming prosthesis. This allows him to use two sticks with a single arm, the second stick using advanced AI routines to drum along with the music in the room.

It’s great to see music being used as a driver to create high-performance prosthetics and push the state of the art forward. We’re sure [Jason] enjoys performing with the new hardware, too. But perhaps you’d like to try something similar, even though you’ve got two hands already? Try this on for size.

Continue reading “AI Prosthesis Is Music To Our Ears” →

Extracting A Vector Font From A Vintage Plotter

January 8, 2018 by Lewin Day 19 Comments

There is a huge variety of hardware out there with a font of some form or other baked into the ROM. If it’s got a display it needs a font, and invariably that font is stored as a raster. Finding these fonts is trivial – dump the ROM, render it as a bitmap, and voilà – there’s your font. However, what if you’re trying to dump the font from a vintage Apple 410 Color Plotter? It’s stored in a vector format, and your job just got a whole lot harder.

The problem with a vector font is that the letters aren’t stored as individual images, but as a series of instructions that, when parsed correctly, draw the character. This has many benefits for generating characters in all manner of different sizes, but makes the font itself much harder to find in a ROM dump. You’re looking for both the instructions that generate the characters, as well as the code used to draw them, if you want a full representation of the font.

The project begins by looking at what’s known about the plotter. The first part of any such job is always knowing where to look, of course. It’s quickly determined that the font is definitely stored in the main ROM, and that there is no other special vector drawing chip or ROMs on board. The article then steps through the search process, beginning with plaintext searches of the binary dump, before progressing to a full disassembly of the plotter firmware. After testing out various assumptions and working methodically, the vector data is found and eventually converted into a modern TrueType font.

In the end, the project is successful, and it’s a great guide on how to approach similar projects. The key is to lay out everything you know at the start, and use that to guide your search step by step, testing and discarding assumptions until you hit paydirt. We’ve seen similar works before, like this project to dump the voice from an ancient Chrysler Electronic Voice Alert.

BrewBuddy Is A Home Brewer’s Best Friend

January 8, 2018 by Kristina Panos 7 Comments

Whether coffee, tea, or beer is your jam, brewing is a delicate pas de deux of time and temperature. Proper brewing of any of these beverages can elevate the experience from average to amazing. With this in mind, [Marcelo] created a time and temperature tool to dial in his beer-brewing process.

BrewBuddy is a complex application-specific timer with an integrated thermometer. It lets him program time and temperature profiles for both the mashing process and the boiling process and store up to 10 steps for each. BrewBuddy doesn’t control the brewing temperature, but it does unify temperature-taking and time-marking into one convenient device that can last about 20 hours on a single CR2032.

The system is based on an STM32 and an LMT86 analog temperature sensor which has been modified to sit inside a stainless steel tube. There are four directional buttons to navigate through intuitive menus to set the desired times and temperatures. As each step completes, the status LED lights up and BrewBuddy waits for confirmation via button push before moving on to the next step. If there’s a problem, the timer can be paused and resumed using the up/down buttons. [Marcelo] is working to perfect the case design, but he already has the board files and firmware up on GitHub. Open up a cold one and check out the demo videos after the break.

After boiling and cooling comes fermentation, and that requires careful monitoring of the sugar content. Here’s a tool for that.

Continue reading “BrewBuddy Is A Home Brewer’s Best Friend” →

Speculative Execution Was A Troublemaker For Xbox 360

January 8, 2018 by Roger Cheng 28 Comments

Part of why people can’t stop talking about Meltdown/Spectre is the fact that all the individual pieces have been sitting in plain sight for a long time. When everyone saw how it all came together last week, many people (and not even necessarily security focused people) smacked themselves on the forehead: “Why didn’t I see that earlier?” Speculative execution has caused headaches going way back. [Bruce Dawson] tells one such story he experienced back in 2005. (Warning: ads on page may autoplay video.)

It’s centered around Xbox 360’s custom PowerPC processor. Among the customization on this chip was the addition of an instruction designed to improve memory performance. This instruction was a hack that violated some memory consistency guarantees held by the basic design, so they knew up front it had to be used very carefully. Even worse: debugging problems in this area were a pain. When memory consistency goes wrong, the code visible in the debugger might not be the actual code that crashed.

Since we’re talking about the dark side of speculative execution, you can already guess how the story ends: no matter how carefully it was used, the special instruction continued to cause problems when speculatively executed outside the constrained conditions. Extensive testing proved that instructions that were not being executed were causing crashes. That feels more like superstition than engineering. As far as he can recall, it ended up being more trouble than it was worth and was never used in any shipped Xbox 360 titles.

[Main image source: AnandTech article on Xbox 360 hardware]