Raspberry Pi Cluster Shows You The Ropes

April 24, 2020 by Bryan Cockfield 28 Comments

Raspberry Pi clusters are a common enough project, but a lot of the builds we see focus on the hardware side of the cluster. Once it’s up and running, though, what comes next? Raspberry Pis aren’t very powerful devices, but they can still be a great project for learning how to interact with a cluster of computers or for experimental test setups. In this project from [Dino], four Pis are networked together and then loaded with a basic set of software for cluster computing.

The first thing to set up, after the hardware and OS, is the network configuration. Each Pi needs a static IP in order to communicate properly. In this case, [Dino] makes extensive use of SSH. From there, he gets to work installing Prometheus and Grafana to use as monitoring software which can track system resources and operating temperature. After that, the final step is to install Ansible which is monitoring software specifically meant for clusters, which allows all of the computers to be administered more as a unit than as four separate devices.

This was only part 1 of [Dino]’s dive into cluster computing, and we hope there’s more to come. There’s a lot to do with a computer cluster, and once you learn the ropes with a Raspberry Pi setup like this it will be a lot easier to move on to a more powerful (and expensive) setup that can power through some serious work.

A Jaw-Dropping Demo In Only 256 Bytes

April 21, 2020 by Elliot Williams 58 Comments

“Revision” is probably the Olympics of the demoscene. The world’s best tiny graphics coders assemble, show off their works, and learn new tricks to pack as much awesome into as few bytes as possible or make unheard-of effects on limited hardware. And of course, there’s a competition. Winning this year’s 256-byte (byte!) competition, and then taking the overall crowd favorite award, was [HellMood]’s Memories.

If you watch it in the live-stream from Revision, you’ll hear the crowd going (virtually) wild, and the announcer losing his grip and gasping for words. It’s that amazing. Not only are more effects put into 2⁸ bytes than we thought possible, but there’s a full generative MIDI score to go with it. What?!?

But almost as amazing is [HellMood]’s generous writeup of how he pulled it off. If you’re at all interested in demos, minimal graphics effects, or just plain old sweet hacks, you have your weekend’s reading laid out for you. [HellMood] has all of his references and influences linked in as well. You’re about to go down a very deep rabbit hole.

Continue reading “A Jaw-Dropping Demo In Only 256 Bytes” →

KVM Uses Many Arduinos

April 19, 2020 by Bryan Cockfield 43 Comments

The Arduino platform is one of the most versatile microcontroller boards available, coming in a wide variety of shapes and sizes perfect for everything from blinking a few LEDs to robotics to entire home automation systems. One of its more subtle features is the ability to use its serial libraries to handle keyboard and mouse duties. While this can be used for basic HID implementations, [Nathalis] takes it a step further by using a series of Arduinos as a KVM switch; although admittedly without the video and mouse functionality yet.

To start, an Arduino Uno accepts inputs from a keyboard which handles the incoming serial signals from the keyboard. From there, two Arduino Pro Micros are attached in parallel and receive signals from the Uno to send to their respective computers. The scroll lock key, which doesn’t do much of anything in modern times except upset Excel spreadsheeting, is the toggle switch between the two outputs. Everything is standard USB HID, so it should be compatible with pretty much everything out there. All of the source code and schematics are available in the project’s repository for anyone who wants to play along at home.

Using an Arduino to emulate a USB input device doesn’t have to be all work and no play, the same basic concept can also be used to build custom gaming controllers.

Typing By Slamming Your Laptop Closed. Repeatedly

April 4, 2020 by Danie Conradie 26 Comments

Do you sometimes feel that your custom mechanical keyboard is not quite loud enough to proclaim your superior hacking powers? Or do you need a more forceful way shout in all caps at someone who is wrong on the internet? For all this and more, [Jesse Li] has got you covered, with a set of bash scripts that allows you to type by slamming your laptop closed repeatedly, using Morse code.

Not the fastest way to type, but definitely the most forceful

The scripts are quite simple, and work receiving the lid open/close events from ACPI (Advanced Configuration and Power Interface), recording the open and close timestamp and converting the timing to dots and dashes. After slamming to the required rhythm, you keep the lid open to see the character appear.

Why would want this? Well, you can now type the letter E by closing your laptop, instead of locking it. Maybe use it to send an emergency message while you’re being held by terrorists in a B-grade action movie. Otherwise, we think this is just an entertaining little hack that’s probably the product of quarantine induced boredom.

Morse code, otherwise known as CW, is still in surprisingly widespread use by ham radio operators, because it’s good at getting messages across intercontinental distances when signal conditions are bad and CW-only ham radio gear is cheap and easy to build yourself. We’ve also covered the Koch Method of learning CW, so don’t be afraid to dabble a bit during the quarantine.

Maxing Out Browser Tabs With 2TB Of Memory

March 30, 2020 by Lewin Day 39 Comments

Tabbed browsing was a gamechanger, allowing users to effectively browse multiple websites at once without losing context. It proved a better solution than using multiple windows, and was an efficiency boon celebrated by all. Many of us are tab fiends, opening great numbers at a time as a habitual part of our workflow. [Linus] decided to find out just how many he could open on a system armed with a full 2TB of RAM.

As may be obvious, setting up a system with 2TB of RAM is no mean feat. Special server-grade RAM modules were sourced, packing 128GB of RAM each, set up for ECC operation. Packing out 16 slots, there’s a performance penalty to addressing so much RAM with a single CPU, but for memory-intensive work, it’s worthwhile. The CPU in question is an AMD 64-core processor, providing plenty of grunt for the task at hand.

In testing, the machine began to slow down long before the RAM was full. Beyond 5000 tabs, things began to crawl. At 6000 tabs, it was simply impractical to open more, with the machine taking a full 26 seconds to respond to a single click. Memory usage at this point was just 200GB, suggesting that software limitations were getting in the way of opening yet more tabs.

While it’s not a useful measure of anything important, it’s fun to explore the limits nonetheless. We’ve seen their projects before, such as this original Xbox casemod. Video after the break.

Continue reading “Maxing Out Browser Tabs With 2TB Of Memory” →

Faking Your Way To USB-C Support On Laptops Without It

March 27, 2020 by Mike Szczys 42 Comments

Is there no end to the dongle problem? We thought the issue was with all of those non-USB-C devices that want to play nicely with the new Macbooks that only have USB-C ports. But what about all those USB-C devices that want to work with legacy equipment?

Now some would say just grab yourself a USB-C to USB-A cable and be done with it. But that defeats the purpose of USB-C which is One-Cable-To-Rule-Them-All^[1]. [Marcel Varallo] decided to keep his 2011 Macbook free of dongles and adapter cables by soldering a USB-C port onto a USB 2.0 footprint on the motherboard.

How is that even possible? The trick is to start with a USB-C to USB 3 adapter. This vintage of Macbook doesn’t have USB 3, but the spec for that protocol maintains backwards compatibility with USB 2. [Marcel] walks through the process of freeing the adapter from its case, slicing off the all-important C portion of it, and locating the proper signals to route to the existing USB port on his motherboard.

[1] Oh my what a statement! As we’ve seen with the Raspberry Pi USB-C debacle, there are actually several different types of USB-C cables which all look pretty much the same on the outside, apart from the cryptic icons molded into the cases of the connectors. But on the bright side, you can plug either end in either orientation so it has that going for it.

Ken Shirriff Unfolds A Nuclear Missile Guidance Computer With Impressive Memory

March 25, 2020 by Mike Szczys 13 Comments

Longtime followers of [Ken Shirriff’s] work are accustomed to say asking “Where does he get such wonderful toys?”. This time around he’s laid bare the guidance computer from a Titan missile. To be specific, this is the computer that would have been found in the Titan II, an intercontinental ballistic missile that you may remember as a key part of the plot of the classic film WarGames. Yeah, those siloed nukes.

Amazingly these computers were composed of all digital logic, no centralized controller chip in this baby. That explains the need for the seven circuit boards which host a legion of logic chips, all slotting into a backplane.

But it’s not the logic that’s mind-blowing, it’s the memory. Those dark rectangles on almost every board in the image at the top of the article are impressively-dense patches of magnetic core memory. That fanout is one of two core memory modules that are found in this computer. With twelve plates per module (each hosting two bits) plus a parity bit on an additional plate, words were composed of 25-bits and the computer’s two memory modules could store a total of 16k words.

This is 1970’s tech and it’s incredible to think that when connected to the accelerometers and gyros that made up the IMU this could use dead reckoning to travel to the other side of the globe. As always, [Ken] has done an incredible job of walking through all parts of the hardware during his teardown. He even includes the contextual elements of his analysis by sharing details of this moment in history near the end of his article.

If you want to geek out a little bit more about memory storage of yore, you can get a handle on core, drum, delay lines, and more in Al Williams’ primer.