The modern smartphone is a marvel of sensors, radios, inputs, outputs, and processing power. In particular, some of those radios, such as WiFi and cellular, have grown fiendishly complex over the years. Even when that complexity is compressed down for the user into the one-dimensional space of the signal strength bars at the top of your phone. So when [David Burgess] was asked to look at some cellphone records of text messages and figure out where some of the more mysterious messages were coming from, it led him down a rabbit hole into the dark arts behind the glowing phone screen.
The number in question was 1111340002, sent by a phone connected to AT&T at the time, and was crucial for a legal case around distracted driving. [David’s] tools in his investigation were YateBTS (a cellular network simulator), SimTrace2 (pictured above), and old reliable Wireshark. Since the number isn’t a specific phone number and is not reachable from the public phone network, it must be a unique number inside AT&T processed by one particular AT&T SMSC (Short Message service center). The SMSC in question is in Atlanta and isn’t a typical texting center, so it must have some particular purpose. The message’s payload is raw binary rather than text, and [David] has done a pretty good job of decoding the majority of the format.
The most exciting revelation in this journey is that the phone (in the traditional sense) does not send this message. The processor on the phone does not know this message and executes no code to send it. Instead, the SIM card itself sends it. The SIM card is connected directly to the baseband processor on the phone, and the baseband polls the sim every so often, asking for any commands. One of those commands is an SMS (though many other commands have worrying consequences).
The SMS that [David] was chasing is triggered whenever a SIM detects a new IMEI, and the message lets the network know what about the previous and current IMEI. However, in the case of this message, it was unlikely that the SIM changed phones, so what happened? After some additional lab work and the deposition of an AT&T employee, [David] showed that a baseband firmware update would also trigger this SMS.
It’s a fascinating journey into the fragmented world of a smartphone’s minds and [David] does a fantastic job on the writeup. If you’re interested in sniffing wireless accessories, you will enjoy this soundbar’s wireless protocol laid bare.
They adorn the ends of Cat5 network patch cables and the flat satin cables that come with all-in-one printers that we generally either toss in the scrap bin or throw away altogether. The blocky rectangular plugs, molded of clear plastic and holding gold-plated contacts, are known broadly as modular connectors. They and their socket counterparts have become ubiquitous components of the connected world over the last half-century or so, and unsurprisingly they had their start where so many other innovations began: from the need to manage the growth of the telephone network and reduce costs. Here’s how the modular connector got that way.
Continue reading “The Modular Connector And How It Got That Way”
The AT&T 3B2 series of computers are historically significant, being the main porting platform for System V Release 3 UNIX. Unfortunately, the documentation for these computers has been nearly lost to the sands of time. They are, however, architecturally interesting machines, and [Seth Morabito] has been working for some time on reverse engineering them. Now, [Seth] is calling it: his AT&T 3B2/400 emulator is almost complete, resurrecting an ancient machine from the dead by studying UNIX source code.
The architecture of this computer is unlike anything you’ve seen before, but well-suited to a UNIX machine. The chipset is built around the WE32100 manufactured by Western Electric, and includes a WE32101 MMU for all the fancy memory-mapped I/O. The implementation of this computer is fairly complex, with oodles of glue logic, over a dozen PALs, and various support chips for a PLL and DRAM controllers. This is computer architecture the way it was intended: inscrutable, baroque, and with a lot of fancy custom chips.
The emulator for this system is a bit simpler: you can just download and run it with simh. This emulator simulates 1, 2, or 4MB of system memory, one 720KB floppy diskette, and either one or two 30MB, 72MB, or 161MB MFM hard disk drives. Not everything is implemented so far — [Seth] is still working on an 8-port serial card and a network card — but this is a minimum viable system for developing and analyzing the history of UNIX.
For those of a certain vintage, no better day at school could be had than the days when the teacher decided to take it easy and put on a film. The familiar green-blue Bell+Howell 16mm projector in the center of the classroom, the dimmed lights, the chance to spend an hour doing something other than the normal drudgery — it all contributed to a palpable excitement, no matter what the content on that reel of film.
But the best days of all (at least for me) were when one of the Bell Laboratory Science Series films was queued up. The films may look a bit schlocky to the 21st-century eye, but they were groundbreaking at the time. Produced as TV specials to be aired during the “family hour,” each film is a combination of live-action for the grown-ups and animation for the kiddies that covers a specific scientific topic ranging from solar physics with the series premiere Our Mr. Sun to human psychology in Gateways to the Mind. The series even took a stab at explaining genetics with Thread of Life in 1960, an ambitious effort given that Watson and Crick had only published their model of DNA in 1953 and were still two years shy of their Nobel Prize.
Produced between 1956 and 1964, the series enlisted some really big Hollywood names. Frank Capra, director of Christmas staple It’s a Wonderful Life, helmed the first four films. The series featured exposition by “Dr. Research,” played by Dr. Frank Baxter, an English professor. His sidekick was usually referred to as “Mr. Fiction Writer” and first played by Eddie Albert of Green Acres fame. A list of voice actors and animators for the series reads like a who’s who of the golden age of animation: Daws Butler, Hans Conried, Sterling Halloway, Chuck Jones, Maurice Noble, Bob McKimson, Friz Freleng, and queen and king themselves, June Foray and Mel Blanc. Later films were produced by Warner Brothers and Walt Disney Studios, with Disney starring in the final film. The combined star power really helped propel the films and help Bell Labs deliver their message.
Continue reading “Retrotechtacular: The Bell Laboratory Science Series”
You’ve heard of Bell Labs, but likely you can’t go far beyond naming the most well-known of discoveries from the Lab: the invention of the transistor. It’s a remarkable accomplishment of technological research, the electronic switch on which all of our modern digital society has been built. But the Bell Labs story goes so far beyond that singular discovery. In fact, the development of the transistor is a microcosm of the Labs themselves.
The pursuit of pure science laid the foundation for great discovery. Yes, the transistor was conceived, prototyped, proven, and then reliably manufactured at the Labs. But the framework that made this possible was the material researchers and prototyping ninjas who bridged the gap between the theory and the physical. The technology was built on what is now a common material; semiconducting substances which would not have been possible without the Labs refinement of the process for developing perfectly pure substances reliably doped to produce the n-type and p-type substances that made diode and transistor possible.
Continue reading “Books You Should Read: The Idea Factory”
A bewildering amount of engineering was thrown at the various challenges presented to the United States by the end of World War II and the beginning of the Cold War. From the Interstate Highway System to the population shift from cities to suburbs, infrastructure of all types was being constructed at a rapid pace, fueled by reasonable assessments of extant and future threats seasoned with a dash of paranoia, and funded by bulging federal coffers due to post-war prosperity and booming populations. No project seemed too big, and each pushed the bleeding edge of technology at the time.
Some of these critical infrastructure projects have gone the way of the dodo, supplanted by newer technologies that rendered them obsolete. Relics of these projects still dot the American landscape today, and are easy to find if you know where to look. One that always fascinated me was the network of microwave radio relay stations that once stitched the country together. From mountaintop to mountaintop, they stood silent and largely unattended, but they once buzzed with the business of a nation. Here’s how they came to be, and how they eventually made themselves relics.
Continue reading “Horns Across America: The AT&T Long Lines Network”
Back in May, Amazon announced the Echo Show, its new version of Alexa with a 7 inch touchscreen. The Echo Show is an interesting device, but will the great unwashed masses pony up $229 to buy the show? That’s $50 more than the original Echo, or $180 more than the Echo Dot. With 5.2 million units sold in 2016, Echo has been a resounding success. This has been in part due to Amazon’s open approach to the API. Anyone can build an Alexa compatible device using a Raspberry Pi. Google has (finally) followed suit with their Home device.
It’s not just the hardware that is accessible. Skills Kit, the programmer interface for extending Echo’s functionality, is also open. At CES this year, Alexa was the belle of the ball. Third party devices are being introduced from all corners, all of them connecting to Amazon’s cloud and responding to the “Alexa” keyword.
The Echo Show takes the family in a new direction. Adding a touch screen gives the user a window on the the world not available with voice interactions. Echo Show also includes a camera, which opens up a whole new set of privacy and security questions. Amazon touts it as a device for viewing security cameras, watching YouTube videos, and making video calls. This puts Echo Show dangerously close to the internet appliance category, essentially a barren wasteland littered with the corpses of previous devices. Does anyone remember when Palm tried this with the 3Com Ergo Audrey? How about the i-Opener? Will Alexa persevere and succeed where others have failed? A lot of it will depend on the third party developers, and how Amazon treats them.
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