Turning Old Cellphones Into SBCs

April 8, 2025 by 35 Comments

[David] sent us a tip about a company in Belgium, Citronics, that is looking to turn old cellphones into single-board computers for embedded Linux applications. We think it’s a great idea, and have long lamented how many pocket supercomputers simply get tossed in the recycling stream, when they could be put to use in hacker projects. So far, it looks like Citronics only has a prototyping breakout board for the Fairphone 2, but it’s a promising idea.

One of the things that’s stopping us from re-using old phones, of course, is the lack of easy access to the peripherals. On the average phone, you’ve got one USB port and that’s it. The Citronics dev kit provides all sorts of connectivity: 4x USB 2.0, 1x Ethernet 10/100M, and a Raspberry Pi Header (UART, SPI, I2C, GPIO). At the same time, for better or worse, they’ve done away with the screen and its touch interface, and the camera too, but they seem to be keeping all of the RF capabilities.

The whole thing runs Linux, which means that this won’t work with every phone out there, but projects like PostmarketOS and others will certainly broaden the range of usable devices. And stripping off the camera and screen has the secondary advantages of removing the parts that get most easily broken and have the least support from custom Linux distros.

We wish we had more details about the specifics of the break-out boards, but we like the idea. How long before we see an open-source implementation of something similar? There are so many cheap used and broken cellphones out there that it’s certainly a worthwhile project!

Protocol Analyzer Remembered

March 30, 2025 by 22 Comments

Anyone will tell you that as hard as it is to create a working system, the real trick is making two systems talk to each other, especially if you created only one or none of them. That’s why tools that let you listen in on two systems talking are especially valuable.

If you were a well-funded lab back in the RS232 days, you might have an HP4957A protocol analyzer. The good news is that if you still use RS232, these kinds of things are now cheap on the surplus market. [IMSAI Guy] got one of these decidedly cool devices and shows it to us in the video below.

The look of these was pretty neat for their time—a folded-up instrument with a cute keyboard and a CRT-100. You can load different interpreters from ROM to RAM, such as the VT-100, which is essentially an application for the device. Of course, now you could rig one of these up in a few minutes with a PC or even a Pi Pico. But it wouldn’t have the same charm, we are sure you would agree.

You can find a lot of old RS232 gear around, from breakout boxes to advanced sniffers like this one. Too bad we couldn’t afford them when we really needed them.

This could be handy if you have a lot of ports. Either real or virtual. Or, do it yourself.

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Custom Slimline CD Player Hides Out Under Speaker

March 27, 2025 by 10 Comments

In the era of digital streaming, the market is full of wireless speakers that will play content from your smartphone or pull it down from the Internet directly over WiFi. But if you’re feeling a bit nostalgic and want to throw on one of your old CDs, well, you might have a problem. That’s the situation [Chad Boughton] recently found himself in, so he decided to build a compact CD player that could discreetly connect up to his fancy Klipsch speaker.

The optical drive itself was the easy part, as [Chad] already had a laptop-style drive in an external enclosure that he could liberate. But of course, the speaker wouldn’t know what to do with an external disc drive, so there needed to be an intermediary. Enter the Raspberry Pi.

It might not look like it at first glance, but that’s a Pi 3 tucked into the back of the 3D printed frame. It would have been too tall in its original configuration, so [Chad] removed the USB and Ethernet ports; a modification we’ve covered in the past. Of course, he still needed to use the USB ports, so he ended up soldering the two cables — one to the CD drive and the other to the back of the speaker — directly to the Pi.

When plugged into the Raspberry Pi, the Klipsch speaker shows up as a USB audio device, so the software side of things was relatively simple. [Chad] installed VLC to handle CD playback, but he still needed a way to control everything. To that end, a IR receiver hooked up to the Pi’s GPIO pins means the Pi can detect the signals coming from the speaker’s original remote and pass the appropriate command on to VLC. The whole thing is very well integrated, and you could be forgiven for thinking it might be some kind of stock upgrade module at first glance.

Despite recently celebrating its 40th birthday, the CD is unlikely to completely disappear from our lives anytime soon. Manufacturers can turn their back on the standard if they want, but so long as folks still want to play them, they’ll keep coming up with inventive ways to make it happen.

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So What Is A Supercomputer Anyway?

March 19, 2025 by 33 Comments

Over the decades there have been many denominations coined to classify computer systems, usually when they got used in different fields or technological improvements caused significant shifts. While the very first electronic computers were very limited and often not programmable, they would soon morph into something that we’d recognize today as a computer, starting with World War 2’s Colossus and ENIAC, which saw use with cryptanalysis and military weapons programs, respectively.

The first commercial digital electronic computer wouldn’t appear until 1951, however, in the form of the Ferranti Mark 1. These 4.5 ton systems mostly found their way to universities and kin, where they’d find welcome use in engineering, architecture and scientific calculations. This became the focus of new computer systems, effectively the equivalent of a scientific calculator. Until the invention of the transistor, the idea of a computer being anything but a hulking, room-sized monstrosity was preposterous.

A few decades later, more computer power could be crammed into less space than ever before including ever higher density storage. Computers were even found in toys, and amidst a whirlwind of mini-, micro-, super-, home-, minisuper- and mainframe computer systems, one could be excused for asking the question: what even is a supercomputer?

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In A World Without USB…

February 19, 2025 by 26 Comments

It is easy to forget that many technology juggernauts weren’t always the only game in town. Ethernet seems ubiquitous today, but it had to fight past several competing standards. VHS and Blu-ray beat out their respective competitors. But what about USB? Sure, it was off to a rocky start in the beginning, but what was the real competition at that time? SCSI? Firewire? While those had plusses and minuses, neither were really in a position to fill the gap that USB would inhabit. But [Ernie Smith] remembers ACCESS.bus (or, sometimes, A.b) — what you might be using today if USB hadn’t taken over the world.

Back in the mid-1980s, there were several competing serial bus systems including Apple Desktop Bus and some other brand-specific things from companies like Commodore (the IEC bus) and Atari (SIO). The problem is that all of these things belong to one company. If you wanted to make, say, keyboards, this was terrible. Your Apple keyboard didn’t fit your Atari or your IBM computer. But there was a very robust serial protocol already in use — one you’ve probably used yourself. IIC or I2C (depending on who you ask).

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Octet Of ESP32s Lets You See WiFi Like Never Before

February 15, 2025 by 14 Comments

Most of us see the world in a very narrow band of the EM spectrum. Sure, there are people with a genetic quirk that extends the range a bit into the UV, but it’s a ROYGBIV world for most of us. Unless, of course, you have something like this ESP32 antenna array, which gives you an augmented reality view of the WiFi world.

According to [Jeija], “ESPARGOS” consists of an antenna array board and a controller board. The antenna array has eight ESP32-S2FH4 microcontrollers and eight 2.4 GHz WiFi patch antennas spaced a half-wavelength apart in two dimensions. The ESP32s extract channel state information (CSI) from each packet they receive, sending it on to the controller board where another ESP32 streams them over Ethernet while providing the clock and phase reference signals needed to make the phased array work. This gives you all the information you need to calculate where a signal is coming from and how strong it is, which is used to plot a sort of heat map to overlay on a webcam image of the same scene.

The results are pretty cool. Walking through the field of view of the array, [Jeija]’s smartphone shines like a lantern, with very little perceptible lag between the WiFi and the visible light images. He’s also able to demonstrate reflection off metallic surfaces, penetration through the wall from the next room, and even outdoor scenes where the array shows how different surfaces reflect the signal. There’s also a demonstration of using multiple arrays to determine angle and time delay of arrival of a signal to precisely locate a moving WiFi source. It’s a little like a reverse LORAN system, albeit indoors and at a much shorter wavelength.

There’s a lot in this video and the accompanying documentation to unpack. We haven’t even gotten to the really cool stuff like using machine learning to see around corners by measuring reflected WiFi signals. ESPARGOS looks like it could be a really valuable tool across a lot of domains, and a heck of a lot of fun to play with too.

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Satellite Internet On 80s Hardware

February 14, 2025 by 2 Comments

Portability has been a goal of a sizable section of the computing world for many decades now. While the obvious products of this are laptops, there are a number of “luggable” PCs that pack more power while ostensibly maintaining their portability. Going back in time past things like the LAN party era of the 90s and 00s takes us to the early era of luggables, with the Commodore SX-64 being one such machine of this era. Its portability is on display in this video where [saveitforparts] is using it to access the Internet over satellite.

The project uses a Glocom Inmarsat modem and antenna to access the internet through a geostationary satellite, but since this computer is about four decades old now this takes a little bit more effort than a modern computer. A Teensy microcontroller is used to emulate a modem so that the Ethernet connection from the satellite modem can be understood by the Commodore. There was a significant amount of setup and troubleshooting required as well, especially regarding IP addresses and networking but eventually [saveitforparts] got the system up and running well enough to chat on a BBS and browse Wikipedia.

One thing he found that might make a system like this relevant for a modern user is that the text-only mode of the Commodore significantly limited data use. For a normal Internet connection this might be a problem, but on a geostationary satellite network where the data is orders of magnitude more expensive, this can be surprisingly helpful. We might not recommend an SX-64 system specifically, but one inspired by similar computers like this text-only cyberdeck might do the trick with the right networking connections.

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