iPhone 6 with Linux boot log on its screen

Boot Mainline Linux On Apple A7, A8 And A8X Devices

June 12, 2022 by Arya Voronova 10 Comments

[Konrad Dybcio] tells about his journey booting Linux on A7/8/8X processors, playing around with an old iPhone 5 he’s got in a drawer. It’s been a two-year “revisit every now and then” journey, motivationally fueled by the things like Linux on M1 Macs announcement. In the end, what we have here is a way to boot mainline Linux on a few less-than-modern but still very usable iPhones, and a fun story about getting there.

[Konrad]’s work is based on the Sandcastle project research, but he couldn’t quite figure out how to make their code work, and had to make sense of it as he went. At some point, he got stuck on enabling the MMU, which was the main roadblock for a while. Joined by another developer intrigued by Apple hardware, they were hacking away at it, developing tools and neat tricks on their way, but to no avail. With the framebuffer accessible and no other decent debugging methods in sight, he tells about a code snippet they wrote that printed register values as valid barcodes Continue reading “Boot Mainline Linux On Apple A7, A8 And A8X Devices” →

The Case For Designer Landline Phones

June 9, 2022 by Kristina Panos 34 Comments

Long before the idea of hot dog-shaped iPhone cases, Otter Boxen, or even those swappable Nokia face plates, people were just as likely to express themselves with their landline phones. Growing up at my house in the 80s, the Slimline on the kitchen wall was hidden inside a magneto wall set from the early 1900s, the front of which swung out to reveal the modern equipment behind it. Back in my bedroom, I had the coolest phone ever, a see-through Unisonic with candy-colored guts. Down in the basement was my favorite extension, tactility-wise: a candy apple-red wall unit with dimly-lit circular push buttons that were springy and spongy and oh-so fun to dial.

Popular culture shows us that people were dreaming of cool telephone enclosures before they were even a thing. Obviously, TV secret agent Maxwell Smart’s shoe phone wasn’t plausible for the technology of that era, but it also wasn’t really feasible for aesthetic reasons. For decades, phone subscribers had to use whatever equipment Ma Bell had to offer, and you couldn’t just buy the things outright at the mall — you had to lease the hardware from her, and pay for the service.

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A Home Payphone

June 4, 2022 by Al Williams 9 Comments

We can’t condone what [Bertrand] did as a kid to make him a fan of payphones, but we get his desire to have one of his own in his home. Even if you don’t want one yourself, he’s got some good shots of the insides of a real phone that came from a casino in Vegas.

As you might expect, these phones were built like tanks. They obviously took a lot of abuse. We had to wonder how much each one cost to produce back in the day. Cleaning up an old phone and getting it to work doesn’t seem like a big effort, but there’s one thing we didn’t think about. Turns out there is a backplate that holds the 50-pound phone up and you need special studs that screw into the phone to hold it up while you put screws through both pieces.

He did connect the phone successfully to a regular phone jack, but his goal was to let his 5-year-old use the phone so he decided to actually wire it to a phone line simulator that just provides a connection between two phones.

New York City recently ripped out its last payphones. They were replaced with multipurpose kiosks, but there are still privately-owned payphones in the city. Of course, you can always use an old payphone as a platform for a different project.

NYC Hangs Up Its Last Pay Phone

May 26, 2022 by Kristina Panos 48 Comments

It was a melancholy Monday this week in the Big Apple as the last public payphone was uprooted from midtown Manhattan near Times Square and hauled away like so much garbage. That oughta be in a museum, you’re thinking, if you’re anything like us. Don’t worry; that’s exactly where the pair is headed.

This all started in 2014 when mayor de Blasio pledged to move the concept of street-level public utility into the future. Since then, NYC’s payphones have been systematically replaced with roughly 2,000 Link Wi-Fi kiosks that provide free domestic phone calls, device charging, and of course, Internet access. They also give weather, transit updates, and neighborhood news.

There are still a few private payphones around the city, so Superman still has places to change, and Bill and Ted can continue to come home. But if you need to make a phone call and have nowhere to turn, a Link kiosk is the way to go.

Although your Cap’n Crunch whistle hasn’t worked in decades, it’s still a sad day in history for the Jolly Wrencher, whose maiden message was about ye olde red boxen. We’re already seeing pay phones live on as art, so that’s a good sign.

Images via PIX11 and CBS News

Build A Prop For A TV Premiere? Stranger Things Have Happened

May 25, 2022 by Kristina Panos 7 Comments

Some guys get all the breaks. [Guy Dupont] had the honor of building a working, interactive wall-mount landline phone for the red carpet premiere of a certain TV show. The phone was to be an Easter egg inside an 80s-style pizzeria set. About every two minutes the phone would ring, and anyone brave enough to answer would be greeted with either a fake pizza order, an old answering machine message, or a clip from The Show That Cannot Be Mentioned.

So the phone doesn’t work-work, but the nostalgia is strong — picking up the receiver when the phone isn’t ringing results in a dial tone, and button pushing leads to the busy signal. Those old pleasant-but-stern operator recordings would have been cool, but there was only so much time. (Your call cannot be completed as dialed. Please check the number and try again.)

[Guy] used a SparkFun RP2040 to handle input from the DTMF keypad and play the tones, the dial and busy signals, and the various recordings into the ear of the receiver.

Instead of messing around with the high voltage needed to drive the original ringer and bell, [Guy] used a small speaker to play the ringing sound. Everything runs on eight AAs tucked under the keypad, which is stepped down to 5 V.

This project was built under fairly dramatic duress, which makes it that much more exciting to watch the build video after the break. With just five days to get the phone working and in the mail, [Guy] holed up on the floor of his office, his messy mid-move refuge from a house plagued by COVID. Unfortunately, the whole pizzeria thing fell through, so [Guy]’s phone will not get to have its moment on the red carpet. But at least it’s on the site that’s black and white and read all over.

[Guy] is no stranger to the old tech/new spec game. Remember that time he shoehorned Spotify into an iPod Classic?

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How A Smartphone Is Made, In Eight “Easy” Blocks

May 9, 2022 by Matthew Carlson 21 Comments

The smartphone represents one of the most significant shifts in our world. In less than thirteen years, we went from some people owning a dumb phone to the majority of the planet having a smartphone (~83.7% as of 2022, according to Statista). There are very few things that a larger percentage of people on this planet have. Not clean water, not housing, not even food.

How does a smartphone work? Most people have no idea; they are insanely complicated devices. However, you can break them down into eight submodules, each of which is merely complex. What makes them work is that each of these components can be made small, at massive economies of scale, and are tightly integrated, allowing easy assembly.

So without further ado, the fundamental eight building blocks of the modern cellphone are: the application processor, the baseband processor, a SIM card, the RF processor, sensors, a display, cameras & lenses, and power management. Let’s have a look at them all, and how they fit together.

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Several relays and switches mounted on a metal frame

The Simplest Electro-Mechanical Telephone Exchange That Actually Works

April 14, 2022 by Robin Kearey 34 Comments

While rarely seen by users, the technology behind telephone exchanges is actually quite interesting. In the first hundred or so years of their existence they evolved from manually-operated switchboards to computer-controlled systems, but in between those two stages was a time when dialling and switching was performed electromechanically. This was made possible by the invention of the stepping switch, a type of pulse-operated relay that can connect a single incoming wire to one of many outgoing wires.

Public telephone exchanges contained hundreds of these switches, but as [dearuserhron] shows, it’s possible to make a smaller system with way fewer components: the Cadr-o-station is built around one single stepper switch. Although it looks rather complicated, the only other components are a bunch of ordinary 24 V relays and a few power supplies. Together they make up a minimal telephone exchange that connects up to ten handsets.

It doesn’t have all the functionality of a larger system however, as only a single voice circuit is made to which all phones are automatically connected. Still, it does allow users to dial a number and let the other phone ring, which might be good enough for a home or indeed the hackerspace where it’s currently sitting. It’s also a fine demonstration of how relatively simple technology can be applied to make a surprisingly complex system.

[dearuserhron] wrote an in-depth article on the workings of electromechanical telephone exchanges, which might come in helpful to anyone who’d like to design such a system for their own home. For a more general introduction into analog phone technology, check out our analysis of a 1970s rotary telephone.

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