A colorful diagram representing the inner structure of the Linux kernel.

Find That Obscure Function With This Interactive Map Of The Linux Kernel

September 14, 2023 by Julian Scheffers 12 Comments

Linux has become one of the largest operating systems on the servers that run large websites, and hopefully, one day, it will be big in the desktop market too. Some of you may know how Linux as an operating system is structured, but have you ever wondered how the kernel itself is structured? Maybe you’ll find this colorful interactive map of the Linux kernel by [Costa Shulyupin] useful.

The interactive map depicts the major levels of abstraction and functionalities, dotted with over 400 prominent functions from the Linux kernel, which are also links to a cross-reference site so you can see all the definitions and usages. It divides the kernel into 7 rows and 7 columns containing domains with well-known terms like security and debugging, but also more obscure things like block devices and address families. These are also links, this time to the definition of the term in question. Finally, there are arrows flying everywhere, to show the relationships between all the many functions in the kernel.
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A rotary subwoofer made out of a speaker coil, a medium-size fan an a grey wooden box to stand on.

Tear Apart Your House For $200 With This Rotary Subwoofer

September 8, 2023 by Julian Scheffers 43 Comments

Many movies and songs use a lot of of bass to make it feel more real to the viewer or listener. Because of this, subwoofers are common in high-quality audio setups, often costing a substantial part of the budget. [Daniel Fajkis] takes the subwoofer to it’s logical extreme by building a rotary subwoofer on a $200 budget.

The principle of a rotary subwoofer is that a normal subwoofer physically moves the air, and so does a fan. If you could make a fan oscillate the air instead of only pushing it, you could turn it into such a subwoofer, which is exactly what [Daniel] did. [Daniel] mounts a large electric motor on the case of an ex-subwoofer to spin the fan. Then, he uses the rotor linkage of a model helicopter and a modified subwoofer speaker to pitch the fan blades, spinning around to create a truly impressive gust of air oscillating at as low as 1 Hz.

The video, after the break, is well made with some good humor, including the legendary quote: “It’s gonna tear apart my household, there’s no way we’re surviving this one.”
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An array of 2D barcodes stored on a ceramic medium. Each 2D barcode is 25 micrometers wide.

Cerabyte: One Terabyte Per Square Centimeter

September 8, 2023 by Julian Scheffers 45 Comments

Most of us will at one point have run out of storage and either had to buy a larger driver or delete some of those precious files. This problem can happen to data centers, too, with the ever-increasing amount of data stored on servers across the world. [Cerabyte] aims to fix this, with their ceramic-based media promising 1 TB/cm² of areal density.

To put into perspective just how much better this density is, we can compare it against SSDs and hard drives. At the time of writing, the densest SSD (NAND flash storage) is claimed to be 0.1825 TB/cm² and the densest hard drive is claimed to be 0.1705 TB/cm², which means 5.48 times and 5.87 times more dense respectively. The density improvement doesn’t end there — both an SSD and a single HDD platter might be a couple millimeters tall, while a [Cerabyte] layer claims to be merely 50 atoms tall.

[Cerabyte] aims to create 10 PB (10,000 TB) and later 1 EB (1,000,000 TB) racks with their technology, a feat difficult to achieve with mere hard drives. The ceramic-based media is written to using lasers and read from with a microscope, though throughput is limited to a “mere” 1 GB/s, which means filling that one rack could take as long as 110 days. Despite the relatively slow access times, we think this new storage technology is impressive, assuming [Cerabyte] succeeds.

Do you need so much storage that even [Cerabyte] can’t satisfy your needs? Simply use YouTube as infinite storage!

A Heathkit H8 in which hides an 8008 instead of the normal 8080

Downgrade Your Heathkit H8 To The World’s First 8-bit Microprocessor

September 6, 2023 by Julian Scheffers 10 Comments

Typically when you’re replacing parts in an old computer it’s either for repairs or an upgrade. Upgrades like adding a more capable processor to an old computer are the most common, and can help bring an old computer a bit closer to the modern era. [Dr. Scott M. Baker] had a different idea, when he downgraded a Heathkit H8 from an 8080 to an 8008.

Despite the very similar numbers, the 8080 runs at four to nearly sixteen times the speed of its predecessor. In addition to this, the 8008 is far less capable on multiple fronts like address space, I/O ports, the stack and even interrupts. The 8008 does have one thing going for it though: the 8008 is widely known as the world’s first 8-bit microprocessor.

A green circuit board with an 8008 and supporting electronics. — The custom 8008 CPU board for the Heathkit H8.

In the video after the break, [Scott] goes into great detail about the challenges presented in replacing the 8080 with the 8008, starting with the clock. The clock is two-phase, so that what would otherwise be a single oscillator now also has a clock divider and two NAND gates.

Boring clock stuff aside, he does some great hacking using the I/O ports including expanding the I/O port count from 32 to the full 256, bit-banging serial, implementing an interrupt controller and even memory mapping 64 KiB into 16 KiB of address space! With that and a few more special adapter circuits, we think [Scott] has done a great job of downgrading his H8 and the resulting CPU board looks fabulous.

Maybe you’re wondering what happens if you upgrade the computer instead of the CPU? What you get is this credit-card sized 6502 computer.

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An automatic laser turret playing with a cat.

Entertain Your Cats Automatically With LazerPaw

September 5, 2023 by Julian Scheffers 22 Comments

Most of us would agree that kittens are very cute, but require lots of attention in return. What would you do if you adopted three abandoned cats but didn’t have all day to play with them? [Hoani Bryson] solved his problem by building LazerPaw — an autonomous, safe way to let your cats chase lasers.

Having recently tinkered with computer vision in the form of OpenCV, [Hoani] decided he would make a laser turret for his cats to play with. An infrared camera, used so that the LazerPaw works in the dark, is mounted to the laser and the Raspberry Pi. These electronics are then mounted on a servo-based pan/tilt module, which is in turn mounted with two smartphone clamps to the ceiling. That way, when the cats chase the laser, they will be looking away from the beam source. Additionally, if the device is aiming directly at a cat, the laser is turned off. Finally, [Hoani] added some NeoPixels with an Arduino-based controller for extra hacker vibes.

The LazerPaw’s software takes in a 30 FPS stream from a webcam, scales it down for performance, and applies a threshold filter to it. When a black pixel, which is assumed to be a cat, is detected, it “pushes” the camera away from it depending on how close to the laser it is. The effect of this is that every time a cat catches up to the laser, it moves away again. The processed images are also sent to an interactive website for remote cat playtime. Finally, there is also a physical start button so you don’t need WiFi to use it.

Is your cat more of a sunbather than a deadly murder beast? Maybe it’ll like this cat chair that follows the sun.

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A scale model of the International Space Station

This Model Mimics The International Space Station

September 4, 2023 by Julian Scheffers 6 Comments

It’s not an overstatement to say that the International Space Station (ISS for short) is an amazing feat of engineering, especially considering that it has been going for over two decades. The international collaboration isn’t just for the governments, either, as many images, collected data and even some telemetry have been made available to the public. This telemetry inspired [Bryan Murphy] and his team to create the ISS MIMIC, a 1:100 scale model of the ISS that reflects its space counterpart.

The model, covered by [3D Printing Nerd] after the break, receives telemetry from the real ISS and actually reflects the orientation of the solar panels accordingly! It also uses this entirely public information to show other things like battery charge level, power production, position above the earth and more on a display. An extra detail we appreciated is the LEDs near the solar panels, which are red, blue or white to indicate using battery, charging battery and full battery respectively. The ISS orbits the earth once every 90 minutes, which can be seen by the LEDs changing color as the ISS enters the shadow of the earth, or exits it.

What could you do to make this better you might ask? Make the it open-source of course! The ISS MIMIC is fully open-source and uses common tools like 3D printing with PLA, Raspberry Pis and Arduinos to make it as accessible as possible for education (and hackers). Naturally, the goal of this project is to educate, which is why it’s open-source and aims to teach programming, electronics, mechatronics and problem solving.

Video after the break.
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Restoring A 45 Year Old Video Game

August 30, 2023 by Julian Scheffers 28 Comments

When we say vintage video game, some of you may think of the likes of Lemmings, Mario or maybe even Donkey Kong but the game that [Vintage Apparatus] restored is slightly older and much more minimalist, using an LED matrix and some 7-segment displays rather than this newfangled color CRT thing.

The front and back covers, buttons and screws of the game on the workbench. — The game is disassembled before cleaning.

[Vintage Apparatus] starts by removing the battery and cover from the 1977 Mattel electronics (American) football game, which uses rather uncommon 2mm triangular screws. To his and our surprise, the circuit board and its beautiful array of LEDs seem to be in excellent condition, so he moves on to cleaning the case itself.

The case, on the other hand, is a bit dirty on the outside, so [Vintage Apparatus] takes out the buttons and starts cleaning with the back cover a Q-tip. After a bit of scrubbing and some extra care to avoid removing any stickers, he moves on to the considerably dirtier and somewhat scratched front case. After some wrestling with the creases and speaker grill of the front cover, the outside of the front case looks nice and clean. Finally, he puts back the buttons and circuit board in the front cover before adding closing it all up with the back cover and screwing it back together.

The game, which immediately comes to life and was actually made by the Mattel calculator division, is a sort of evasion game where the player is a bright dot that can move forward, up or down. The player avoids the dimmer dots, the “tacklers”, in order to run as far as possible as fast as possible. When one of the tacklers tackles the player, the amount of downs is increased and the fifth down means game over. After either scoring or getting downed one too many times, the field is flipped and it’s now player 2’s turn.

Video after the break.
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