All posts by Stephen Cass

This Classic Calculator Was Literally Reverse Engineered From the Bare Metal

Post Syndicated from Stephen Cass original

Was the Sinclair Scientific calculator elegant? It certainly was a hit, gracing the cover of publications like Popular Mechanics after its release in 1974. Cleverly written firmware dragooned its limited processor, intended only for basic arithmetic, into performing way beyond specifications. This allowed Sinclair to sell a scientific calculator to countless folks who otherwise could not have afforded one. But it was also slow and sometimes inaccurate, provided barely enough mathematical functions to qualify as a scientific calculator, and was difficult for the uninitiated to use.

I’d vaguely known of this calculator because of its place as a milestone toward the birth of the British microcomputer industry and such beloved machines as the Sinclair ZX Spectrum. So I clicked when I came across Chris Chung’s replica kit of the calculator on the Tindie marketplace. Then I read the description of how the original calculator worked—scientific notion only? no “equals” button?—and how the replica reproduced its behavior, by using an emulator running firmware that had been reverse engineered by visually examining the metal of an original processor. This I had to try.

Let’s first get to the hardware. The kit is one of a number of Sinclair calculator replicas, but it wins points for simplicity: One chip and a credit-card-size printed circuit board are combined with a small handful of discrete components. Chung actually offers two kits: his original, developed in 2014 but put on Tindie in late 2019, displays numbers using two small QDSP-6064 bubble LED modules [PDF], which have the classic look of 1970s calculators but are long discontinued and hard to get. His 2020 update of the kit uses modern seven-segment LED displays. The difference in rarity is reflected in the price: The 2020 version costs US $39, while the original version costs $79. However, in a nice touch, the original version lets you have your cake and eat it with regard to the bubble LEDs: The through holes in the PCB are sized to create a friction fit. This means you don’t have to solder in the modules, preserving them for some future project.

Both versions are functionally identical, based around a MSP430 microcontroller. The MSP430 eliminates the need for most of the other components found in the Sinclair Scientific, and runs an emulator of the TMS080x family of chips. The TMS080x family was built by Texas Instruments (TI), and specific versions, like the TMS0805 used in the Sinclair Scientific, were differentiated by the contents of the chip’s 3,520-bit ROM.

For many years, how Sinclair coaxed this chip into performing magic remained locked away in TMS0805 chip ROMs. That began to change in 2013, when Ken Shirriff got wind of the Sinclair Scientific after getting involved with the Visual 6502 team. This group likes to reverse engineer classic chips, for which the original design drawings are often lost. Sometimes this involves etching chip packages away with acid and carefully photographing the exposed silicon dies with a microscope to see the individual transistors. Shirriff was able to create a generic simulator of a TMS080x chip in JavaScript just by studying Texas Instruments’ patent filings, but the specific code used in the Sinclair’s TMS0805’s ROM still eluded him, until Visual 6502 team member John McMaster took photographs of an exposed die in 2014.

Shirriff is no stranger to IEEE Spectrum due to his extensive work in the history of computing, so I emailed him to ask how he’d gone from a micrograph to working code. By looking at how the metal oxide gates were laid down in the ROM section of the chip, “I was able to extract the raw bits the same day,” Shirriff wrote back. “Phil Mainwaring, Ed Spittles, and I spent another day figuring out how the raw bits corresponded to the code….The code was 320 words of 11 bits, but the ROM was physically 55 rows and 64 columns.…Through a combination of examining the circuitry, analyzing patterns in the bits, and brute-force trying a bunch of combinations, we figured out the arrangement and could extract the code.”

Once he had the code loaded into his simulator, Shirriff could tease out its workings. The algorithms used throughout “were essentially the simplest brute-force algorithms that could get an answer. But there were some interesting mathematical tricks they used to get more accuracy, not to mention programming tricks to get the code to fit,” he explained. (If you want detailed explanations, Shirriff maintains an online version of his simulator that lets you step through the code, line by line.)

The Sinclair Scientific was able to reduce complexity by using reverse Polish notation, in which mathematical operators come after the numbers they are operating on—for instance, “5 + 4 =” becomes “5 4 +.” The trigonometric functions used an iterated approximation technique that could take several seconds to produce results and were often accurate only to the first three significant figures. The calculator also used fixed scientific notation for everything—there was no way to enter a decimal point. So rather than entering “521.4,” you’d enter “5214,” which is displayed as “5.214”; then you’d press “E” and enter “2,” making the number “5.214 x 102.” Only one number could be entered at a time.

On paper this looks terrible, something you’d have used only if you couldn’t afford, say, the HP-35, whose designers prided themselves on accuracy and functionality (although the HP-35 also used reverse Polish notation, it did so in a more sophisticated way).

But Sinclair wasn’t trying to compete against other calculators; he was competing against slide rules. I’d read that point in histories before, but I didn’t really understand its meaning until I held this kit in my hand. By chance, I’d also recently purchased a vintage Pickett slide rule and learned how to do basic operations with it, thanks to the lessons available on the International Slide Rule Museum website. As I used the Sinclair Scientific, I was struck by how conceptually similar it was to using my slide rule. There, two- to three-figure accuracy is the norm, the rule’s sliding “cursor” means you’re passing just one number between scales, and you typically don’t bother about magnitudes—you work with the most significant figures and make a mental estimate to insert the decimal point at the end, so that 52 x 2 and 5,200 x 20 are calculated in exactly the same way.

This realization is why I feel replica kits are so important—they are an easy way to provide the understanding that only comes from operating a device with your own hands. It was a great reminder that, as folks like Henry Petroski have pointed out, good design is not really something that exists as an abstract ideal but as something that exists only within a specific context. So, was the Sinclair Scientific elegant? For me, the answer is a resounding yes.

This article appears in the June 2020 print issue as “The Sinclair Scientific, Remade.”

9 New Suggestions For Bored Engineers

Post Syndicated from Stephen Cass original

IEEE COVID-19 coverage logo, link to landing page

Like many of you, IEEE Spectrum’s staff is still working from home. As the weeks have turned into months, we’ve had to find ways to occupy our minds and hands. A few weeks ago, we looked through Spectrum’s archives to find 19 things you can do with minimal space and resources. Now here’s a new selection of ideas to keep cabin fever at bay:

Al Alcorn, Creator of Pong, Explains How Early Home Computers Owe Their Color Graphics to This One Cheap, Sleazy Trick

Post Syndicated from Stephen Cass original

In March, we published a Hands On article about Matt Sarnoff’s modern homebrew computer that uses a very old hack: NTSC artifact color. This hack allows digital systems without specialized graphics hardware to produce color images by exploiting quirks in how TVs decode analog video signals.

NTSC artifact color was used most notably by the Apple II in 1977, where Steve “Woz” Wozniak’s use of the hack brought it to wide attention; it was later used in the IBM PC and TRS-80 Color Computers. But it was unclear where the idea had originally come from, so we were thrilled to see that video game and electrical engineering legend Allan Alcorn left a comment on the article with an answer: the first color computer graphics that many people ever saw owe their origin to a cheap test tool used in a Californian TV repair shop in the 1960s. IEEE Spectrum talked to Alcorn to find out more:

Stephen Cass: Analog NTSC televisions generate color by looking at the phase of a signal relative to a reference frequency. So how did you come across this color test tool, and how did it work?

Al Alcorn: When I was 13, 14, my neighbor across the street had a television repair shop. I would go down there and at the same time, I had my father sign me up for an RCA correspondence course on radio and television repair. So, by the time I got to Berkeley, I was a journeyman TV repairman and actually paid my way through college through television. In one repair shop, there was a real cheap, sleazy color bar generator [for testing televisions]. And instead of doing color properly by synthesizing the phases and stuff like that, it simply used a crystal that was 3.58 megahertz [the carrier frequency for the color signal] minus 15.750 kilohertz, which was the horizontal scan frequency. So it slipped one phase, 360 degrees, every scan line. You put that signal on the screen and you’ve got a color bar from left to right. It really was really the cheapest, sleaziest way of doing it!

SC: How did that idea of not doing NTSC “by the book” enter into your own designs?

AA: So, I learned the cheap, sleazy way doing repair work. But then I got a job at Ampex [a leader in audio/visual technology at the time]. Initially, I wanted to be an analog engineer, digital was not as interesting. At Ampex, it was the first time I saw video being done by digital circuits; they had gotten fast enough, and that opened my eyes up. [Then I went to Atari]. Nolan [Bushnell, co-founder of Atari] decided we wanted to be in the home consumer electronics space. We had done this [monochrome] arcade game [1972’s Pong] which got us going, but he always wanted to be in the consumer space. I worked with another engineer and we reduced the entire logic of the Pong game down to a single N-channel silicon chip. Anyway, part of the way into the design, Nolan said, “Oh, by the way, it has to be colored.” But I knew he was going to pull this stunt, so I’d already chosen the crystal [that drove the chip] to be 3.58 MHz, minus 15.750 kilohertz.

SC: Why did you suspect he was going to do that?

AA: Because there never was a plan. We had no outline or business plan, [it was just Nolan]. I’m sure you’ve heard that the whole idea behind the original arcade Pong was that it was a test for me just to practice, building the simplest possible game. But Nolan lied to me and said it was going to be a home product. Well, at the end it was kind of sad, a failure, because I had like 70 ICs in it, and that was [too expensive] for a home game. But [then Nolan decided] it would work for an arcade game! And near the end of making [arcade] Pong, Nolan said, “Well, where’s the sound?” I said “What do you mean, sound?” I didn’t want to add in any more parts. He said “I want the roar of the crowd of thousands applauding.” And [Ted] Dabney, the other owner said “I want boos and hisses.” I said to them “Okay, I’ll be right back.” I just went in with a little probe, looking for around the vertical sync circuit for frequencies that [happened to be in the audible range]. I found a place and used a 555 timer [to briefly connect the circuit to a loudspeaker to make blip sounds when triggered]. I said “There you go Nolan, if you don’t like it, you do it.” And he said “Okay.” Subsequently, I’ve seen articles about how brilliant the sound was!  The whole idea is to get the maximum functionality for the minimum circuitry. It worked. We had $500 in the bank. We had nothing and so we put it out there. Time is of the essence.

SC: So, in the home version of Pong, the graphics would simply change color from one side of the screen to the other?

AA: Right, the whole goal for doing this was just to put on the box: “Color!” Funny story—home Pong becomes a hit. This is like in 1974, 75. It’s a big hit. And they’re creating advertisements for television. Trying to record the Pong signal onto videotape. I get a call from some studio somewhere, saying, “We can’t get it to play on the videotape recorder, why?”  I say, “Well, it’s not really video! There’s no interlace… Treat it as though it’s PAL, just run up through a standard converter.”

SC: How does Wozniak get wind of this?

AA: In those days, in Silicon Valley, we didn’t keep secrets. I hired Steve Jobs on a fluke, and he’s not an engineer. His buddy Woz was working at HP, but we were a far more fun place to hang out. We had a production floor with about 30 to 50 arcade video games being shipped, and they were on the floor being burnt in. Jobs didn’t get along with the other guys very well, so he’d work at night. Woz would come in and play while Jobs did his work, or got Woz to do it for him. And I enjoyed Woz. I mean, this guy is a genius, I mean, a savant. It’s just like, “Oh my God.”

When the Apple II was being done, I helped them. I mean, I actually loaned them my oscilloscope, I had a 465 Tektronix scope, which I still have, and they designed the Apple II with it. I designed Pong with it. I did some work, I think, on the cassette storage. And then I remember showing Woz the trick for the hi-res color, explaining, sitting him down and saying, “Okay, this is how NTSC is supposed to work.” And then I said, “Okay. Now the reality is that if you do everything at this clock [frequency] and you do this with a pulse of square waves…” And basically explained the trick. And he ran with it.  That was the tradition. I mean, it was cool. I was kind of showing off!

SC: When people today are encouraged to tinker and experiment with electronics, it’s typically using things like the Arduino, which are heavily focused on digital circuits. Do you think analog engineering has been neglected?

AA: Well, it certainly is. There was a time, I think it was in the ’90s, where it got so absurd that there just weren’t any good analog engineers out there. And you really need analog engineers on certain things. A good analog engineer at that time was highly paid. Made a lot of money because they’re just rare. So, yeah. But most kids want to be—well, just want to get rich. And the path is through programming something on an iPhone. And that’s it. You get rich and go. But there is a lot of value in analog engineering. 

Lessons Learned by NYC Makers Producing Personal Protective Equipment for Medics

Post Syndicated from Stephen Cass original

A coalition of 14 makerspaces, hospitals, and unions has organized to create and distribute face shields and other protective equipment to frontline nurses and doctors coping with a wave of COVID-19 cases in New York City.

They made their first delivery of 97 shields on 22 March, and currently have enough capacity to produce between 500 and 1,000 shields a day, according to Jake Lee, a computer science masters student at Columbia University and spokesperson for the coalition called NYC Makes PPE. And they’ve some tips for other engineers and makers itching to put their skills and facilities to use.

Show The World You Can Write A Cool Program Inside A Single Tweet

Post Syndicated from Stephen Cass original

Want to give your coding chops a public workout? Then prove what you can do with the BBC Micro Bot. Billed as the world’s first “8-bit cloud,” and launched on 11 February, the BBC Micro Bot is a Twitter account that waits for people to tweet at it. Then the bot takes the tweet, runs it through an emulator of the classic 1980s BBC Microcomputer running Basic, and tweets back an animated gif of three seconds of the emulator’s output. It might sound like that couldn’t amount to much, but folks have been using it to demonstrate some amazing feats of programming, most notably including Ebon Upton, creator of the Raspberry Pi.

“The Bot’s [output] posts received over 10 million impressions in the first few weeks, and it’s running around 1000 Basic programs per week,” said the account’s creator, Dominic Pajak, in an email interview with IEEE Spectrum.

Upton, for example, performed a coding tour de force with an implementation of Conway’s Game of Life, complete with a so-called Gosper Gun, all running fast enough to see the Gun spit out glider patterns in real time. (For those not familiar with Conway’s Game of Life, it’s a set of simple rules for cellular automata that exist on a flat grid. Cells are turned on and off based on the state of neighboring cells according to those rules. Particularly interesting patterns that emerge from the rules have been given all sorts of names.)

Upton did this by writing 150 bytes of data and machine code for the BBC Microcomputer’s original CPU, the 6502, which the emulator behind the BBC Micro Bot is comprehensive enough to handle. He then converted this binary data into tweetable text using Base64 encoding, and wrapped that data with a small Basic program that decoded it and launched the machine code. Since then, people have been using even more elaborate encoding schemes to pack even more in. 

Pajak, who is the vice-president of business development for Arduino, created the BBC Micro Bot because he is a self-described fan of computer history and Twitter. “It struck me that I could combine the two.” He chose the BBC Micro as his target because “growing up in the United Kingdom during the 1980s, I learnt to program the BBC Micro at school. I certainly owe my career to that early start.” Pajak adds that, “There are technical reasons too. BBC Basic was largely developed by Sophie Wilson (who went on to create the Arm architecture) and was by far the best Basic implementation of the era, with some very nice features allowing for ‘minified’ code.”

Pajak explains that the bot is written in Javascript for the Node.js runtime environment, and acts as a front end to Matt Godbolt’s JSbeeb emulation of the BBC Micro. When the bot spots a tweet intended for it, “it does a little bit of filtering and then injects the text into the emulated BBC Micro’s keyboard buffer. The bot uses ffmpeg to create a 3-second video after 30 seconds of emulation time.” Originally the bot was running on a Raspberry Pi 4, but he’s since moved it to Amazon Web Services.

Pajak has been pleasantly surprised by the response: “The fact that BBC BASIC is being used for the first time by people across the world via Twitter is definitely a surprise, and its great to see people discovering and having fun with it. There were quite a lot of slogans and memes being generated by users in Latin America recently. This I didn’t foresee for sure.”

The level of sophistication of the programs has risen sharply, from simple Basic programs through Upton’s Game of Life implementation and beyond. “The barriers keep getting pushed. Every now and then I have to do a double take: Can this really be done with 280 characters of code?Pajak points to Katie Anderson’s tongue-in-cheek encoding of the Windows 3.1 logo, and the replication of a classic bouncing ball demo by Paul Malin—game giant Activision’s technical director—which, Pajak says, uses “a special encoding to squeeze 361 ASCII characters of code into a 280 Unicode character tweet.”

If you’re interested in trying to write a program for the Bot, there are a host of books and other coding advice about the BBC Micro available online, with Pajak hosting a starting set of pointers and a text encoder on his website,

As for the future and other computers, Pajak says he given some tips to people who want to build similar bots for the Apple II and Commodore computers. For himself, he’s contemplating finding a way to execute the tweets on a physical BBC Micro, saying “I already have my BBC Micro connected to the Internet using an Arduino MKR1010…”

19 Suggestions for Bored Engineers

Post Syndicated from Stephen Cass original

Thanks to the Covid-19 pandemic, a lot of us find ourselves working from home (including all of your editors here at IEEE Spectrum). To help stave off cabin fever, we looked through our recent archives for things that would best occupy your minds and hands, even if you don’t have much space. In the coming days we’ll be on the look out for more ideas—so if you have any tips or suggestions for your fellow readers, please send them to [email protected].

4 Missions Will Search the Martian Atmosphere and Soil for Signs of Life

Post Syndicated from Stephen Cass original

graphic link to special report landing page

In 2020, Earth and Mars will align. Every 26 months, a launch window for a low-energy “Hohmann” transfer orbit opens between the two. This July, no fewer than four missions are hoping to begin the nine-month journey.

ExoMars 2020

A joint mission between the European Space Agency (ESA) and Roscosmos, the Russian space agency, ExoMars 2020 is dedicated to the search for life, including anything that might be alive today. A Russian-built lander is intended to carry a European rover to the Martian surface. But the mission is technically challenging, and some experts doubt that Roscosmos is up to its task. “They’re relying on a Russian-built lander, which is worrying,” says Emily Lakdawalla, a senior editor at the Planetary Society. “Russia has not launched a successful planetary mission since 1984.” ESA has also acknowledged that there’s some doubt about whether the mission will launch at all, as the parachutes that will be used during landing have run into problems during high-altitude testing.

Assuming the spacecraft does alight on the Martian soil, the lander, called Kazachok, will monitor the climate and probe for subsurface water at the landing location. Meanwhile the rover, named Rosalind Franklin, will go further afield. Rosalind Franklin is equipped with a drill that can penetrate up to 2 meters beneath the ground, where organic molecules are more likely to be preserved than on the harsh surface. An onboard laboratory will analyze samples and in particular look at the molecules’ “handedness.” Complex molecules typically come in “right-handed” and “left-handed” versions. Nonbiological chemical reactions involve both in equal measure, but biology as we know it strongly prefers either right- or left-handed molecules in any given metabolic reaction.

Mars 2020

NASA’s mission will explore the Martian surface using substantially the same rover design as that of the plutonium-powered Curiosity, which has been trundling around the Gale crater since 2012. The big difference is in the payload. Mars 2020 has a suite of scientific instruments based on the premise that Mars was much warmer and wetter billions of years ago, and that life may have originated then. Mars 2020 will look for evidence of ancient habitable environments and for chemical signatures of any microbes that lived in them.

Mars 2020 is also a test bed, with two major prototype systems. The first is the Mars Oxygen In-Situ Resource Utilization Experiment [PDF], or MOXIE. About the size of a car battery, MOXIE converts the carbon dioxide atmosphere of Mars into oxygen using electrolysis. Demonstrating this technology, albeit on a small scale, is a critical step toward human exploration of Mars.

The other prototype is the Mars Helicopter, a solar-powered, 1.8-kilogram autonomous twin-rotor drone. To cope with the thin Martian atmosphere, the rotors will spin 10 times as fast as those of a helicopter on Earth. If it can successfully take off, it will be the first aircraft to fly on another world. Currently five flights are planned for distances of up to a few hundred meters. “It makes the [rover] engineers twitch a little bit to help to accommodate that kind of stuff, but it is awfully fun,” says Lakdawalla.


In 2011, the first attempt by the China National Space Administration (CNSA) to send a probe to Mars failed when the Russian rocket carrying it couldn’t get out of Earth orbit. So the Chinese are going with their own Long March rocket for their next try. The HX-1 mission will search for the signs of life with an orbiter and a small rover. The rover has been fitted with a ground-penetrating radar that should have a much deeper range—up to 100 meters—than similar radars on ExoMars and Mars 2020, which can reach only a few meters down.

Although technical details about the mission are sparse, the CNSA has momentum behind it. “It’s really astonishing what they have accomplished with their lunar missions,” says Lakdawalla. She’s impressed that the Chinese engineers succeeded in depositing a lander and rover on the moon’s surface in 2013 “on their first-ever effort to land on another world.” Such success bodes well for Mars, she says: “They’ve clearly demonstrated technical capability and interplanetary navigation.”


The United Arab Emirates is another country hoping to make a big leap. The UAE space agency was officially established only in 2014, and the country’s space experience is limited to a few Earth-orbiting observation and communications satellites. Now the country plans to send an orbiter called Hope to Mars to study its atmosphere, in hopes of understanding how it evolved into today’s tenuous blanket of carbon dioxide and other trace gases. It plans to use a Japanese rocket and launch site.

Despite the UAE’s inexperience, its chances of entering the Mars club aren’t bad, explains Lakdawalla. “It is just an orbiter, so I think success on the first try is a lot easier, given how routine it’s become to put things in orbit,” she says. Lakdawalla notes that the UAE has excellent international partnerships, and says the new space agency isn’t focused on doing all of the technology development itself: “The UAE is about hiring the best consultants and getting help to leapfrog their own technology.”

This article appears in the January 2020 print issue as “Life on Mars?”

Build a Vector Graphics Display Clock with a Cathode-Ray Tube

Post Syndicated from Stephen Cass original

Once upon a time, there was a type of particle accelerator so popular that it was mass-produced by the million. Engineers and scientists at their benches, and folks at home in their living rooms, would carefully arrange themselves to watch the dancing glow of a beam of subatomic particles smashing into a phosphorescent screen. This attention-hogging accelerator was, of course, the cathode-ray tube (CRT), which reigned supreme as the electronic display technology for decades, before being unceremoniously relegated to the figurative and literal trash heap of history by flat-screen technologies.

But there are still CRTs to be found, and you can put some of them to great use with Howard Constantine’s US $100 Oscilloscope Clock Kit. The kit works with many CRTs that were designed to be used in oscilloscope-type displays and operated with relatively low voltages—in the range of hundreds, rather than thousands, of volts.

As CRTs are becoming as unfamiliar to modern engineers as amplifier tubes did to the transistor generation, a quick recap of a few salient points is likely in order here. Oscilloscope-type CRTs are different from those found in televisions and most computer monitors. TV-type CRTs use magnetic fields generated by coils located outside the vacuum tube to deflect an electron beam, which is scanned line by line across the screen to build up what’s called a raster image. Oscilloscope-type CRTs use two pairs of horizontally and vertically oriented plates located inside the tube to electrostatically deflect the beam: This approach was handy for oscilloscopes because an analog input voltage can control the vertical position of the beam directly (albeit filtered through some signal-conditioning circuitry), while an internal timing circuit controls the horizontal deflection, letting engineers see time-varying signals.

The beam’s horizontal deflection can also be controlled with a second input voltage (called X-Y, or vector, mode). This made oscilloscope CRTs appealing to early computer-graphics pioneers, who pressed them into service as displays for things like radar defense networks. Some seminal computer games were made using vector displays, including arguably the first-ever video game, the 1958 Tennis for Two, and the massive 1979 arcade hit Asteroids. But vector displays struggled when it came to, say, showing bitmaps or even simply a large area filled with a solid color, and so eventually lost out to raster displays.

But CRT vector displays have a distinct look that’s hard to replicate—not least when the screen is round, which was the easiest shape to make back in the day. (I do find it a little ironic that after decades of engineers striving to create the most perfectly flat and rectangular displays possible, smartphone makers have begun rhapsodizing about offering partially curved screens with rounded corners.)

The Oscilloscope Clock Kit allows you to recapture that look. The kit itself comprises the printed circuit board and all the accompanying components, including two PIC microcontrollers—one controls the clock and generates the graphics and text, while the other is dedicated to periodically shifting the clock around the screen to avoid phosphor burn-in. Normally you have to supply your own enclosure and CRT (eBay usually has listings), but as Constantine has a limited stock he uses to make fully assembled clocks for sale, he kindly let me buy a 7-centimeter-wide DG7-6 from him for $75 and one of his acrylic enclosures for $40.

Getting a clear enclosure was important to me because I wanted to be able to show off the tube for maximum effect, while also keeping fingers safely away from the electronics. This is important because even though the CRT is considered “low voltage,” that still means 300 volts in some parts of the circuitry. Perhaps I was particularly skittish on this topic because of childhood memories: When I demonstrated a burgeoning propensity for taking things apart with a screwdriver, my father, a broadcast engineer, headed off any designs I might have had on our TV set with lurid true tales of people being zapped by the charge stored in a television’s high-voltage capacitors even after the set had been unplugged.

Fortunately for my nerves, the clock kit’s smaller capacitors pose much less of a hazard. Nonetheless, now that even 5 V is increasingly shunned as a circuit-melting torrent of electricity, I recommend builders work with a little more caution than they are used to, especially as checking stages of the build do require probing it with a multimeter when the board is plugged in.

Soldering the through-hole components was straightforward, although because the tallest component—a transformer—is one of the first required, it’s likely you’ll need to use some kind of circuit-board holder rather than trying to lay the board flat when working. The biggest obstacle came when it was time to wire up my DG7-6 CRT. The kit provides 10 leads for operating a CRT—two that supply a few volts of alternating power to the heater filament to raise the cathode temperature enough for thermoelectric emission to come into play, one that has a constant negative voltage of about 295 V to provide the cathode’s supply of electrons, three that connect to a train of accelerating and focusing electrodes in the neck of the CRT, and four that connect to the horizontal and vertical deflecting plate pairs. But my DG7-6 only had nine pins! A check of the DG7-6’s data sheet [PDF] (which I found on Frank Philipse’s wonderful archive) showed that the cathode and one side of the heater filament shared a pin. A quick email to Constantine revealed the solution was a quick fix: All I had to do was jumper the cathode connection to one of the filament leads. After that, the instructions stepped me through the calibration steps required to produce a sharp bright test dot in the center of the screen rather than a fuzzy dim elliptical blob off to the side.

When building the kit, you can incorporate one of two optional $40 add-on circuits that eliminate the need to set the clock manually—a Wi-Fi module and a GPS module. Without one of those, the clock automatically detects whether it is plugged into a 50- or 60-hertz wall socket and uses that frequency as a reference time base. Setting the clock manually is simply a matter of pushing a “fast set” and “slow set” button until the clock shows the correct time.

The end result is an eye-catching timepiece that restores a CRT to its rightful place: the center of attention.

This article appears in the January 2020 print issue as “Oscilloscope Clock.”

IEEE Spectrum’s 2019 Gift Guide

Post Syndicated from Stephen Cass original

  • Pinball

    As IEEE Spectrum reported at the end of last year, pinball is having a revival, driven in part by the shift to e-commerce, which is turning erstwhile big-box retail stores into cheap real estate for family entertainment centers. Modern pinball machines, with enhancements like upgradable software, are vastly more sophisticated than their electromechanical ancestors. Stern Pinball is in the vanguard of this renaissance, making home and arcade versions of many of its games. The latest title available in a home version is the US $4,500 Star Wars Pin, based on comics artwork and models inspired by the original movie trilogy.

  • Classic Microprocessor Kit

    Wichit Sirichote is a professor at King Mongkut’s Institute of Technology, in Bangkok. He’s also the maker of a terrific line of single-board computers based on classic CPUs such as the 6502, Z80, and 8088. Prices range from $85 to $175, depending on the CPU. They are bare-bones machines designed for learning and protoyping, but they are very flexible: You can upload code through an RS-232 port, plug in a standard LCD character display directly using an onboard connector, and add other custom hardware via a bus-expansion slot. Sirichote wrote his own monitor software for the boards that lets you, for example, examine the contents of CPU registers, and extensive documentation is available.

  • Artie 3000

    Artie 3000 is a modern version of the classic turtle drawing robot that could be found in classrooms connected to a microcomputer running the Logo language. But what’s really nice about the $70 Artie is that unlike with the turtles of old, you can easily program it in a variety of ways. At the most basic level, you can control Artie and its pen directly, remote-control style, and then move on up through various graphical block languages and into full-fledged Python and JavaScript. Budding programmers benefit from a gentle learning curve, and advanced coders interested in procedurally generated art get access to a cheap robot.

  • Musical Tesla Coil Kit

    It’s not going to win awards for the quality of its sound, but it is a crowd pleaser. OneTesla’s $400 Musical Tesla Coil Kit can be driven directly by a MIDI-enabled instrument or play a MIDI file. The frequency of the notes is used to modulate the output of the coil with a square wave, producing buzzing notes and impressive sparks over half a meter long. A smaller version is also available for $230.

  • Doppel

    Doppel is worn like a watch, except you wear it on the inside of your wrist rather than on the outside. A rotating weight inside creates a rhythmic vibration. The purpose of the $280 wearable is to improve focus and reduce stress, by using rhythms that are faster or slower, respectively, than your normal resting heart rate. (The accompanying smartphone app measures your heart rate when you place your finger over your phone’s camera lens and looks at changes in the ambient light that gets filtered through.) It did help reduce my anxiety levels somewhat, but I found it worked best with deliberate mindfulness techniques, so if you’re not already familiar with those, your mileage may vary.

  • Piper Computer Kit

    Minecraft is already used to introduce children to writing software. The $300 Piper Computer Kit, aimed at 8- to 13-year-olds, extends that idea to hardware. Kids first assemble the wooden case and plug together the basic components of the kit, which is based on a Raspberry Pi and comes with its own screen. While the kit includes a mouse, there is no keyboard. Instead a breadboarding module is provided, which can be used to, for example, wire up buttons to control events in Minecraft through a series of game levels.

  • Books

    If you’re looking for a nonfiction book to give, try one from the Platform Studies series from MIT Press. These books describe influential platforms in the history of digital media, examining how the specific technical details and hardware capabilities of each platform (or, in academia-speak, “affordances”) shaped the software that ran on them and how that combination in turn affected the industry and wider culture. The most recent 2019 title (The Media Snatcher) dissects the PC Engine/TurboGrafx-16 console. The highlights of the series so far for me are Racing the Beam, about the Atari 2600, and Minitel.

    In the fiction department, Spectrum’s recommendation is Fall, or Dodge in Hell (William Morrow, 2019) by Neal Stephenson, author of the cyberpunk classic Snow Crash. Fall is a sequel of sorts to his 2011 novel, Reamde, but it can be read completely independently of Reamde (and is in fact a much better book). Reamde is an entertaining enough technothriller, but Fall is Stephenson at his best, weaving together deep philosophical questions against the background of a compelling vision of the future (a chapter featuring a journey across an America that’s been utterly fragmented by competing social-media feeds is plausibly chilling). In Fall, the lead character awakens in a digital afterlife, in which his first order of business is to create a universe to live in.

This article appears in the December 2019 print issue as “2019 Holiday Gift Guide.”

Got an Old Canon Point-and-Shoot Camera? Hack It

Post Syndicated from Stephen Cass original

A decade is a long time in technology—long enough for a technology to go from hot product to conspicuously obsolete to retro cool. In 2010, IEEE Spectrum’s David Schneider wrote about a hack to supplant the firmware in Canon point-and-shoot cameras and add new features, such as motion detection. As it turns out, at the time point-and-shoot cameras were near their zenith of popularity. Since then, while compact stand-alone digital cameras are still being made, their sales have shrunk dramatically. As the smartphone camera became the most ubiquitous type of camera on the planet, point-and-shoot cameras found themselves relegated to the back of the closet.

That was certainly the case with our Canon PowerShot S80. My wife bought it in 2008 primarily to document her paintings in between professional photo shoots, and a few years later we replaced it with a mirrorless Nikon 1 J-1 with interchangeable lenses. So when I found the S80 while decluttering recently, I wondered: Was it just e-waste now, or could it be combined with today’s technology to do interesting things?

I decided the perfect test case for my S80 was variable time-lapse photography. This is a task for which even an 11-year-old digital camera, with its larger optics, can compete with today’s smartphones on image quality. This scenario makes mobility a moot point, but the task also requires more sophistication than even CHDK—the open-source firmware replacement David Schneider wrote about in 2010—can easily offer alone.

My S80’s original firmware had a function that would take a photograph at fixed intervals of between 1 and 60 minutes, in 1-minute increments. CHDK provides a script that allows a more fine-grained increment of 1 second, but I wanted to try time-lapse photography of the Empire State Building, which we happen to have a good view of from Spectrum’s New York office. During the day, the light changes slowly, so I wanted to shoot one photo every few minutes. At dusk, however, the lighting on and around the building changes more dramatically, so I wanted photos taken at a faster rate.

The first thing was to test my camera. It’s a credit to Canon that despite years of disuse, all the parts sprang to life. The only problem was on the battery side. I had three batteries, one of which refused to charge at all, and two others I no longer trusted for a long-duration experiment, so I found a DC adapter on eBay that powers the camera from a wall socket.

Then I installed CHDK. Fortunately, this is one of those rare pieces of open-source software for which the documentation is a comprehensive and intelligible wiki. Looking up the instructions for my S80, I determined its current firmware, which turned out to be 1.00f. Only the 1.00g version is compatible with CHDK, so I followed the instructions to upgrade the factory firmware, the biggest obstacle to which was finding the right utility software to open the 7z format that the firmware file was compressed with.

A cross-platform tool called Stick makes finishing the CHDK install easy: Drop a photo taken with a camera onto the tool’s interface and it analyzes the metadata and downloads the exact version of CHDK required onto a SD card. Launching CHDK on my camera just requires putting the prepared card in and pressing the S80’s “shortcut” button.

CHDK provides an interface for remote control of the camera via the USB link normally used to download photographs directly to a PC. A number of programs can use this PTP standard, including chdkptp, which offers both a command line version and a graphical user interface (GUI) version that lets you see what is being displayed in the viewfinder screen live. One of the nice things about chdkptp is that a precompiled binary, bundled with required supporting libraries, is available for the Raspberry Pi, thus eliminating dependency hell.

I ran into two problems, which were resolved after searches of CHDK’s user forums. The first was that chdkptp couldn’t connect to the S80—a helper process on the Pi was grabbing the connection, assuming I wanted to download photos. The simplest solution was to find the offending process using a “ps -ax | grep gphoto2” command, and “kill -9” it. (This works only on a per-session basis; if you want to permanently disable the helper, you’ll have to edit some deep configuration files.)

My camera and chdkptp could now connect, but I still couldn’t actually take a photo. This was solved by writing a script with some mode commands I found on a forum. CHDK runs the script when I press the camera’s shutter, and then it is happy to accept remote commands.

To implement my variable time-lapse schedule, I wrote a short Python program on the Pi. I looked up the time of the sunset and set the Python program to check the clock. Outside a half-hour window around sunset it would take a photo every 10 minutes, and one every 30 seconds inside the window. To control the S80, I just issued an OS call to the chdkptp command line tool that connected and triggered the shutter—that is, os.system(“./ -c -eshoot”).

I left the system running from the early afternoon till dusk, and when I returned I had 113 images, which I dumped into iMovie to make a time-lapse video. Ta-da!

Now that I have my proof of concept, it would be a straightforward task to write a Python script that could download the times of sunrise and sunset and adjust itself automatically. I can also save images directly to the Pi. Then I could access and download these images remotely over a wireless network, allowing for the option of leaving the camera and Pi in place for long periods of time for truly epic time-lapse movies.

This article appears in the December 2019 print issue as “Hack Your Old Point-and-Shoot.”

You Want a Prosthetic Leg With a Tesla Coil and Spark Gaps? No Problem

Post Syndicated from Stephen Cass original

Imagine performing complicated choreography with thousands of volts rippling up and down inside your leg, creating a ladder of buzzing miniature bolts of lightning. That’s what Viktoria Modesta does in a promotional art video released this week for Rolls Royce’s line of Black Badge cars. The video, which you can see at the bottom of this page, is in a “cybernetic glam” style that shows Modesta striding through futuristic settings until she transforms into the famous leaning woman ornament that adorns the front bonnet of Rolls Royces.

Modesta is a self-described bionic pop artist who often uses very elaborate versions of her prosthetic limb. To create her outfit for the video—including the 3D printed matching bodice—she turned to fashiontech designer Anouk Wipprecht (who wrote about her creation of a maker-friendly EEG headset in the June issue of IEEE Spectrum) and Sophie de Oliveira Barata of the Alternative Limb Project.

Modesta, Wipprecht, and de Oliveira Barata started visiting their local Rolls Royce dealerships and brainstorming about what Modesta’s look could be for the video. Wipprecht began thinking about using a Tesla coil to generate electric “wings,” and brought on two previous collaborators: Joe DiPrima (profiled in Spectrum’s May issue) and his brother John. The DiPrima’s are the founders of ArcAttack, which makes and performs with Tesla coils. ArcAttack often makes large coils, some of which have been installed as attractions in U.S. science museums. Soon the team began wondering if they could put a Jacob’s Ladder inside a hollow leg. (If you’ve ever seen an old-school mad scientist’s laboratory in a movie, you’re familiar with the rising spark effect of a Jacob’s Ladder).

But while “Jacob Ladders are cool things, they’re sort of unreliable. If you’re walking around with it and the wind starts blowing and stuff like that, it just breaks the arc. Maybe it might work like one out of five times,” says Joe DiPrima. Given that the video was designed to promote a car, “I thought that maybe we could design a Jacob’s Ladder worked more like a distributor cap in a car. So we have an actual mechanical switch that switches high voltage from the Tesla coil and energizes a specific spark gap. And so by doing that we make the effect bulletproof.” The result was a series of spark gaps which can fire in a Jacob’s Ladder-like way, but with the speed and pattern under the control of a programmable microcontroller. Wipprecht and DiPrima shared with IEEE Spectrum some behind-the-scenes footage of how they prototyped and built the leg for this video:

Making a wearable Tesla coil came with unusual challenges: “A Tesla coil doesn’t have a lot of capacitance when they’re super small. So they’re really sensitive to their surroundings as far as frequency is concerned and stuff like that,” says DiPrima—even a nearby hand can affect the coil. “One of the things that I did to make the frequency of the coil more stable is I put a capacitor string inside of it…that added 20 picofarads of capacitance, which is pretty significant for a coil that small.” As well as stabilizing the coil itself, the extra capacitance gave the design more flexibility with regard to the length of the wires used to connect to the spark gaps in the leg.

It was decided to fit the coil and the supported electronics into a shoe, so they worked with United Nude to make a custom pair that would let them fit everything into the heel. The development process took about six months and grew to include a number of other specialists, such as Alex Freire.

“I’m not a prosthetist,” says Wipprecht. For an artifical leg “there’s really specific needs, like the socket placement, the length of the feet, the balance.” Freire made the sockets and the feet which were then sent to de Oliveira Barata to complete the leg based on Wipprecht’s design sketches, which featured an open space for the spark electrodes. The feet are made of rubber, while the upper part of the prosthetic is made of carbon fiber, but much of the length is made from fiberglass. “That is the space where the electrical effects needed to happen, so it couldn’t be carbon fiber because that’s conductive,” says Wipprecht.

In the finished video, these effects have been enhanced using CGI, but it is still based on real sparks as a practical effect. The bodice Modesta wears is designed to evoke the engine of the Black Badge car. To create it, Wipprecht worked from a 3-D body scan of Modesta, and printed the form using a nylon material with a laser-sintering printer. The printed neck and hip parts were used to make a mold from which parts were cast, which where then layered with the same carbon fiber material used in Black Badge cars.

Revealing the Hidden Beauty of Common Components

Post Syndicated from Stephen Cass original

Eric Schlaepfer showcases the surprisingly intricate structures of capacitors, LEDs, connectors, and other often-overlooked parts

As we’ve remarked in these pages before, oftentimes some of the best engineering around is invisible, hidden inside black boxes of one sort or the other. If the black box is sufficiently important in some way, professional forensic and reverse engineers can be employed to crack it open and reveal its secrets. But what about more humble items, such as the apparently unremarkable components that make up everyday electronics? Who cares enough to take the trouble to look inside them?

Eric Schlaepfer does. To the delight of a growing following, in March of this year, Schlaepfer started posting to his @TubeTimeUS twitter account magnified cross sections of capacitors, cables, LEDs, transistors, and more, usually with accompanying annotations.

His photography project began in a moment of idle curiosity, after fixing an old function generator that he used to test other circuits. He’d just finished replacing a number of capacitors. “I was kind of staring down at my desk, looking at these dead tantalum capacitors, and I picked one up,” he says. “I was just going to throw it in the waste can, but then I realized that I don’t really know what’s inside these things, and it might actually be interesting to take a look inside…so I just took out a sheet of sandpaper and started going at it.”

Schlaepfer took photos of the results and tweeted them, where they quickly drew a positive response. Encouraged, Schlaepfer dug around in his junk box, pulled out a standard quarter-watt carbon film resistor, and sanded away. He got another wave of positive responses. “It’s the sort of component that most hobbyists have experience with, right? People really like that,” says Schlaepfer, who began sanding down every component he could find.

Schlaepfer usually has plenty of candidates on hand. He is a hardware engineer at Google who’s also well known in the maker and vintage electronics communities and a frequent visitor to electronic flea markets, so he always has. He is the creator of the MOnSter 6502, a replica of the legendary 6502 processor made using thousands of surface mount transistors, and he also created the Three Fives kit, which lets you build a version of the venerable 555 timer chip using discrete transistors and resistors, and which IEEE Spectrum featured in our March 2014 issue.

The components take Schlaepfer anywhere from a few minutes to several hours to prepare, gradually moving to finer and finer grades of sandpaper. (He’s tried using electrical sanders and cutters to speed things up, but he says he has the best luck with sandpaper and elbow grease.) To take photographs of the exposed surfaces, Schlaepfer typically uses an old inspection microscope and simply holds his cellphone’s camera over the eyepiece. For items that are too large for the microscope, he uses a Nikon D40 DSLR with a 105-mm macro lens.

“There’s a sort of a surprising beauty in a lot of these components,” says Schlaepfer. He notes that although engineers often have knowledge of how a component works in the abstract, the actual physical structure can be unexpected: “For example, I know that an electrolytic capacitor is made up of foil elements, wound with a paper material in between that holds the electrolyte…. But until I actually cut one in half in the axial direction, I didn’t know that it had this really interesting looking set of two interlocking spirals, which was the two plates of the capacitor.”

Schlaepfer also makes his cross sections publicly available on the Wikimedia Commons and is mulling a coffee-table book, although if he did that he’d “have to invest in a bit more complex photography rig!” he says, laughing.

This article appears in the August 2019 print issue as “The Hidden Beauty of Components?”

Chip Hall of Fame: MOS Technology 6581

Post Syndicated from Stephen Cass original

A synthesizer that defined the sound of a generation

1982 was a big year for music. Not only did Michael Jackson release Thriller, the bestselling album of all time, but Madonna made her debut. And it saw the launch of the Commodore 64 microcomputer. Thanks to the C64, millions of homes were equipped with a programmable electronic synthesizer, one that’s still in vogue.

The C64 became the bestselling computer of all time (some 17 million were sold) largely because it had graphics and sound capabilities that punched way above the system’s price tag: US $600 on release, soon falling to $149. Like many machines from that era, the C64 has a devoted following in the retrocomputing community, and emulators are available that let you run nearly all its software on modern hardware. What’s unusual is that a specific supporting chip inside the C64 has also retained its own dedicated following: the 6581 SID sound chip.

The C64 was developed by MOS Technology in 1981. MOS had already had a hit in the microcomputing world with its creation of the 6502 CPU in 1975. That chip—and a small family of variants—was used to power popular home computers and game consoles such as the Apple II and Atari 2600. As recounted in IEEE Spectrum’s March 1985 design case history [PDF] of the C64 by Tekla S. Perry and Paul Wallich, MOS originally intended just to make a new graphics chip and a new sound chip. The idea was to sell them as components to microcomputer manufacturers. But those chips turned out to be so good that MOS decided to make its own computer.

Creation of the sound chip fell to a young engineer called Robert Yannes. He was the perfect choice for the job, motivated by a long-standing interest in electronic sound. Although there were some advanced microcomputer-controlled synthesizers available, including the Super Sound board designed for use with the Cosmac VIP system, the built-in sound generation tech in home computers was relatively crude. Yannes had higher ambitions. “I’d worked with synthesizers, and I wanted a chip that was a music synthesizer,” Yannes told Spectrum in 1985. His big advantage was that MOS had a manufacturing fab on-site. This allowed for cheap and fast experimentation and testing: “The actual design only took about four or five months,” said Yannes.

On a hardware level, what made the 6581 SID stand out was better frequency control of its internal oscillators and, critically, an easy way for programmers to control what’s known as the sound envelope. Early approaches to using computers to generate musical tones (starting with one by Alan Turing himself) produced sound that was either off or on at a fixed intensity, like a buzzer. But most musical instruments don’t work that way: Think of how a piano note can be struck sharply or softly, and how a note can linger before decaying into silence. The sound envelope defines how a note’s intensity rises and falls. Some systems allowed the volume to be adjusted as the note played, but this was awkward to program. Yannes incorporated data registers into the 6581 SID so a developer could define an envelope and then leave it to the chip to control the intensity, rather than adjusting the intensity by programming the CPU to send volume-control commands as notes played (something few developers bothered to attempt).

The SID chip has three sound channels that can play simultaneously using three basic waveforms, plus a fourth “noise” waveform that produces rumbling to hissing static sounds, depending on the frequency. The chip has the ability to filter and modulate the channels to produce an even wider range of sounds. Some programmers discovered they could tease the chip into doing things it was never designed to do, such as speech synthesis. This was perhaps most famously used in Ghostbusters, a 1984 game based on the movie of the same name in which the C64 would utter low-fidelity catchphrases from the movie, such as “He slimed me!”

But stunts like speech synthesis aside, the SID chip’s design meant that home computer games could have truly musical soundtracks. Developers started hiring composers to create original works for C64 games—indeed, some titles today are solely remembered because of a catchy soundtrack.

Unlike in modern game development, in which soundtrack creation is technically similar to conventional music recording (up to, and including, using orchestras and choirs), these early composers had to be familiar with how the SID chip was programmed at the hardware level, as well as its behavioral quirks. (Because the chip got to market so quickly, MOS’s documentation of the 6581 SID was notoriously lousy, with Yannes acknowledging to Spectrum in 1985 that “the spec sheet got distributed and copied and rewritten by various people until it made practically no sense anymore.”)

At the time, these composers were generally unknown outside the games industry. Many of them moved on to other things after the home computer boom faded and their peculiar hybrid combination of musical and programming expertise was less in demand. In more recent years however, some of them have been celebrated, such as the prolific Ben Daglish, who composed the music for dozens of popular games.

Daglish (who created my favorite C64 soundtrack, for 1987’s Re-Bounder) was initially bemused that people in the 21st century were still interested in music created for, and by, the SID chip, but he became a popular guest at retrocomputing and so-called chiptunes events before his untimely death in late 2018.

Chiptunes (also known as bitpop) is a genre of original music that leans into the distinctive sound of 1980s computer sound chips. Some composers use modern synthesizers programmed to replicate that sound, but others like to use the original hardware, especially the SID chips (with or without the surrounding C64 system). Because the 6581 SID hasn’t been in production for many years, this has resulted in a brisk aftermarket for old chips—and one that’s big enough that crooks have made fake chips, or reconditioned dead chips, to sell to enthusiasts. Other people have created modern drop-in replacements for the SID chip, such as the SwinSID.

There are several options if you’d like to listen to a classic C64 game soundtrack or a modern chiptune without investing in hardware. You can find many on YouTube, and projects like SOASC= are dedicated to playing tunes on original SID chips and recording the output using modern audio formats. But for a good balance between modern convenience and hard-core authenticity, I’d recommend using a player like Sidplay, which emulates the SID chip and can play music data extracted from original software code. Even after the last SID chip finally burns out, its sound will live on.

An abridged version of this article appears in the July 2019 print issue as “Chip Hall of Fame: SID 6581.”

Rovers Will Unroll a Telescope on the Moon’s Far Side

Post Syndicated from Stephen Cass original

Astronomers need a quiet place to observe the cosmic dawn

graphic link to special report landing page
graphic link to special report landing  page

For decades, astronomers have gazed up at the moon and dreamed about what they would do with its most unusual real estate. Because the moon is gravitationally locked to our planet, the same side of the moon always faces us. That means the lunar far side is the one place in the solar system where you can never see Earth—or, from a radio astronomer’s point of view, the one place where you can’t hear Earth. It may therefore be the ideal location for a radio telescope, as the receiver would be shielded by the bulk of the moon from both human-made electromagnetic noise and emissions from natural occurrences like Earth’s auroras.

Early plans for far-side radio observatories included telescopes that would use a wide range of frequencies and study many different phenomena. But as the years rolled by, ground- and satellite-based telescopes improved, and the scientific rationale for such lunar observatories weakened. With one exception: A far-side telescope would still be best for observing phenomena that can be detected only at low frequencies, which in the radio astronomy game means below 100 megahertz. Existing telescopes run into trouble below that threshold, when Earth’s ionosphere, radio interference, and ground effects begin to play havoc with observations; by 30 MHz, ground-based observations are precluded.

In recent years, scientific interest in those low frequencies has exploded. Understanding the very early universe could be the “killer app” for a far-side radio observatory, says Jack Burns, an astrophysics professor at the University of Colorado and the director of the NASA-funded Network for Exploration and Space Science. After the initial glow of the big bang faded, no new light came into the universe until the first stars formed. Studying this “cosmic dawn [PDF],” when the first stars, galaxies, and black holes formed, means looking at frequencies between 10 and 50 MHz, Burns says; this is where signature emissions from hydrogen are to be found, redshifted to low frequencies by the expansion of the universe.

With preliminary funding from NASA, Burns is developing a satellite mission that will orbit the moon and observe the early universe while it travels across the far side. But to take the next step scientifically requires a far larger array with thousands of antennas. That’s not practical in orbit, says Burns, but it is feasible on the far side. “The lunar surface is stable,” he says. “You just put these things down. They stay where they need to be.”

This article appears in the July 2019 print issue as “The View From the Far Side.”

You Don’t Need Sight to Read These Electronic Schematics

Post Syndicated from Stephen Cass original

Lauren Race has refined circuit symbols for use in tactile diagrams

When I was growing up, I remember reading in an electronics-for-young-folk book that good vision was a must-have if you wanted to build or design electronics: Even color blindness was a serious limitation. This was a myth. In fact, there’s an active community of people with low or no vision who are using today’s maker ecosystem to solve problems in their daily lives. And with some tweaks to the familiar symbols used in circuit diagrams, that community could grow even larger.

“The Arduino platform is actually wonderful for accessibility because we can create our own tools. We can create things that might be expensive on the market and customize them to our needs,” says Chancey Fleet, the assistive technology coordinator at the Andrew Heiskell Braille and Talking Book Library in New York City. “There’s specific techniques that we use for soldering and for getting around the board,” says Fleet, giving the example of how some people use a Braille stylus to count pins as though it’s “a tiny cane navigating the header.” (For more details about how to work as a visually impaired maker, Fleet recommends the Blind Arduino Project.)

However, one big obstacle to introducing blind and low-vision people to electronics is circuit diagrams. Experienced builders can use written descriptions of a circuit, but beginners, in particular, benefit from the kind of spatial information provided by a schematic. This came home to Lauren Race when she was a graduate student at New York University’s Interactive Telecommunications Program (ITP), which bills itself as a “center for the recently possible.”

ITP had accepted its first blind and low-vision students, which prompted Tom Igoe, who teaches the introductory physical computing class to make the course materials more accessible. The class’s labs are built around the Arduino Uno microcontroller, but the schematics were inaccessible to these students. Because of her previous career as an art director and designer, Race was recruited by Igoe to look into converting the schematics into a tactile form, which developed into her thesis project.

Race began by printing the class’s circuit diagrams directly onto Swell Touch Paper. Often used by schools and museums to create tactile images and other graphics, this paper makes lines and areas printed in black ink swell up to create a raised surface when a sheet is passed through a fuser machine. “I quickly realized after I did a usability test that these don’t work. [Just] printing out what’s there, and making it tactile, does not make it readable,” says Race. So she started iterating, and reached out to assistive technology experts in the blind and low-vision community such as Fleet and Joshua Miele, creator of the Blind Arduino Project.

Race used a methodology called participatory design “where your users are involved in the design process the entire way through…. You partner with blind designers and partner with blind makers. And that was really important to me because as a sighted designer, I have no business making something for somebody whose needs I don’t understand,” says Race.

Race and her team eventually went through 11 iterations, evolving circuit symbols so they were legible to sighted and blind people alike. They simplified symbols where possible—“we took a lot of noise out”—and made sure there was 6 millimeters of space between subelements so that it was easier to distinguish them: “So the switch opened up. The polarized capacitor was opened up… Even the spacing between the arrows of the LED symbol,” says Race. In addition, hollow shapes for elements like arrowheads were chosen over solid shapes “because hollow is tactilely more discernible.”

The revised symbols and an accompanying style guide are available for anyone to download and use, along with 50 complete schematics from ITP’s physical computing class, at

This article appears in the July 2019 print issue as “Electronic Schematics for Blind Makers.”