Ever hear of a Mersenne prime? These are prime numbers that are one less than a power of two. Named after Marin Mersenne, a French Minim friar, who studied them in the early 17th century, there is a distributed computing project on the Internet to find Mersenne primes called GIMPS (Great Internet Mersenne Prime Search). The project recently announced they have found the largest known prime.
From the late 80s to the early 90s, [Steve Jobs] wasn’t at Apple. He built another company in the meantime, NeXT Computer, a company that introduced jet black workstations to universities and institutions, developed an incredible emphasis on object-oriented programming, and laid the groundwork for the Unix-ey flavor of Apple’s OS X. Coincidently, there is a lot of old NeXT gear at the Adafruit clubhouse – not that there’s anything wrong with that, we all have our own strange affectations and proclivities. Recently, [Lady Ada] turned one of the strangest components of the NeXT computer ecosystem into something useful: a computer speaker.
The item in question for this build is the NeXT ‘sound box’. When not using the very special NeXT monitor, the NeXT computer connects the monitor, keyboard, and speakers through this odd little box. There are two versions of the NeXT sound box, and peripherals from either version are incompatible with each other. ([Jobs] was known for his sense of design and a desire for a simplified user experience, you know.)
In [Lady Ada]’s initial teardown of the sound box, she discovers a few interesting things about this peripheral. There’s an I2S DAC inside there, connected to an unobtanium DB19 connector. Theoretically, that I2S device could be used to drive the speaker with digital audio. The only problem is the DB19 connector – they’re rare, and [Steve] from Big Mess o’ Wires bought the world’s supply.
Without these connectors, and since it’s only an hour-long show, [Lady Ada] went with the most effective hack. She grabbed a USB audio dongle/card, added a small amplifier, and soldered a few wires onto the power and ground pins of an IC. It’s simple, effective, fast, and turns an awesome looking 30-year-old peripheral into a useful device.
[ModPurist] sent us his Raspberry-Pi-in-a-Nintendo casemod. Before you go hitting the back button, this is a good one because it’s so well executed. And it’s actually a two-fer: he’d previously built up a wireless NES controller that completes the setup.
Both of these mods are hacks in the purest sense of the word. The controller mod took a wireless keyboard’s sending circuit board and wedged it inside the NES controller. The original NES controller reads out the buttons into a shift register and sends that down a wire. That’s all gone. [ModPurist] just wired up each button to the sender PCB and figured out which keys they corresponded to on the PC by pressing the buttons. Simple.
The best part of his video about building the controller? After about a minute in, he forgets that he’s filming a technical how-to video and plays Pokemon for the remaining four minutes. That’s the sign of success.
Then there’s the NES hack itself. He stripped everything out, added a Raspberry Pi 2 and a fan, made it all work with the power switch and the original TV outs, and it’s done. Again, nothing more than needs doing, but nothing less. It looks just right plugged up to the CRT monitor (from a C64, no less), and there’s no doubt that being able to play wirelessly on an original NES controller is cool.
This isn’t [ModPurist]’s first time here on Hackaday either, and his “Cold Boy” fridge-turned-Gameboy is a work of art.
Sorting. It’s a classic problem that’s been studied for decades, and it’s a great first step towards “thinking algorithmically.” Over the years, a handful of sorting algorithms have emerged, each characterizable by it’s asymptotic order, a measure of how much longer an algorithm takes as the problem size gets bigger. While all sorting algorithms take longer to complete the more elements that must be sorted, some are slower than others.
For a sorter like bubble sort, the time grows quadradically longer for a linear increase in the number of inputs; it’s of order O(N²).With a faster sorter like merge-sort, which is O(N*log(N)), the time required grows far less quickly as the problem size gets bigger. Since sorting is a bit old-hat among many folks here, and since O(N*log(N)) seems to be the generally-accepted baseline for top speed with a single core, I thought I’d pop the question: can we go faster?
In short — yes, we can! In fact, I’ll claim that we can sort in linear time, i.e a running time of O(N). There’s a catch, though: to achieve linear time, we’ll need to build some custom hardware to help us out. In this post, I’ll unfold the problem of sorting in parallel, and then I”ll take us through a linear-time solution that we can synthesize at home on an FPGA.
Need to cut to the chase? Check out the full solution implemented in SystemVerilog on GitHub. I’ve wrapped it inside an SPI communication layer so that we can play with it using an everyday microcontroller.
To understand how it works, join us as we embark on an adventure in designing algorithms for hardware. If you’re used to thinking of programming in a stepwise fashion for a CPU, it’s time to get out your thinking cap!
While sorely lacking in pictures of the innards of this digital canvas, we were extremely impressed with the work that went into making such a convincing object. [Clay Bavor] wanted a digital picture frame, but couldn’t find one on the market that did what he wanted. They all had similar problems, the LCDs were the lowest quality, they were in cheap bezels, they had weird features, they had no viewing angle, and they either glowed like the sun or were invisible in dark environments.
[Clay] started with the LCD quality, he looked at LCD specs for the absolute best display, and then, presumably, realized he lived in a world where money is no object and bought a 27″ iMac. The iMac has a very high pixel density, no viewing angle, and Apple goes through the trouble of color balancing every display. Next he got a real frame for the iMac, cut a hole in the wall to accommodate it, and also had a mat installed to crop the display to a more convincing aspect ratio for art. One of the most interesting part of the build is the addition of a Phidgets light sensor. Using this, he has some software running that constantly adjusts the Mac to run at a brightness that’s nearly imperceptible in the room’s lighting.
Once he had it built he started to play around with the software he wrote for the frame. Since he wanted the frame to look like a real art print he couldn’t have the image change while people were looking, so he used the camera on the Mac and face detection to make sure the image only changed when no one was looking for a few minutes. He also has a mode that trolls the user by changing the image as soon as they look away.
We admit that a hackier version of this would be tearing the panel out of a broken iMac and using a lighter weight computer to run all the display stuff. [Clay] reached the same conclusion and plans to do something similar for his version 2.0.
Solderless breadboards are extremely handy. You always hear, of course, that you need to be careful with them at high frequencies and that they can add unwanted capacitance and crosstalk to a circuit. That stands to reason since you have relatively long pieces of metal spaced close together — the very definition of a capacitor.
[Ryan Jensen] did more than just listen to that advice. He built a circuit and used a scope to investigate just how much coupling he could expect with a simple digital circuit. Better still, he also made a video of it (see below). The test setup shows a single gate of a hex Schmitt trigger inverter with a sine wave input. The output transitions ring and also couple back into the input.
The early days of electricity appear to have been a cutthroat time. While academics were busy uncovering the mysteries of electromagnetism, bands of entrepreneurs were waiting to pounce on the pure science and engineer solutions to problems that didn’t even exist yet, but could no doubt turn into profitable ventures. We’ve all heard of the epic battles between Edison and Tesla and Westinghouse, and even with the benefit of more than a century of hindsight it’s hard to tell who did what to whom. But another conflict was brewing at the turn of 19th century, this time between an Indian polymath and an Italian nobleman, and it would determine who got credit for laying the foundations for the key technology of the 20th century – radio.
