Mockup of a printed copy of the Little OS Book

One Book To Boot Them All

April 2, 2025 by Heidi Ulrich 19 Comments

Somewhere in the universe, there’s a place that lists every x86 operating system from scratch. Not just some bootloaders, or just a kernel stub, but documentation to build a fully functional, interrupt-handling, multitasking-capable OS. [Erik Helin and Adam Renberg] did just that by documenting every step in The Little Book About OS Development.

This is not your typical dry academic textbook. It’s a hands-on, step-by-step guide aimed at hackers, tinkerers, and developers who want to demystify kernel programming. The book walks you through setting up your environment, bootstrapping your OS, handling interrupts, implementing virtual memory, and even tackling system calls and multitasking. It provides just enough detail to get you started but leaves room for exploration – because, let’s be honest, half the fun is in figuring things out yourself.

Completeness and structure are two things that make this book stand out. Other OS dev guides may give you snippets and leave you to assemble the puzzle yourself. This book documents the entire process, including common pitfalls. If you’ve ever been lost in the weeds of segmentation, paging, or serial I/O, this is the map you need. You can read it online or fetch it as a single 75-page long PDF.

Mockup photo source: Matthieu Dixte

BreadboardOS, A Command Line Interface For The Pico

May 14, 2024 by Lewin Day 25 Comments

Operating systems! They’re everywhere these days, from your smart TV to your smartphone. And even in your microcontrollers! Enter BreadboardOS for the Raspberry Pi Pico.

BreadboardOS is built on top of FreeRTOS. It’s aim is to enable quick prototyping with the Pi Pico. Don’t confuse operating system with a graphical environment — BreadboardOS is command-line based. You’d typically interface with it via a serial terminal emulator, but joy of joys, it does support color!

Using BreadboardOS is a little different than typical microcontroller development. Creating an application involves adding a “service” which is basically a task in FreeRTOS parlance. The OS handles running your service for you. Via the text interface, you can query running services, and start or kill them at will.

Meanwhile, running df will happily give you stats on the flash usage of the Pi Pico, and free will tell you how full the memory is doing. If you really want to get raw, you can make calls to control GPIO pins, the SPI hardware, or other peripherals, and do it right on the command line.

BreadboardOS isn’t for everyone, but it could prove a useful tool if you like that way of doing things. It’s not the only OS out there for the Pi Pico, either!

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Install ChimeraOS And Never Leave The Sofa

August 10, 2023 by Dave Rowntree 9 Comments

There are some projects that initially don’t seem to make sense, but actually turn out to have valid use cases. ChimeraOS appears to be one of those. The idea is that if you own a gaming PC, but it is not necessarily located where you want to be all the time (like in a gaming den or office for example) then ChimeraOS allows you to play games on it remotely via a local machine. That machine may be a media PC attached to your main TV, or perhaps a mobile device like a steam deck.

With support for AMD GPUs only, there is one issue with deployment — if you’re an Nvidia owner you’re out of luck — the premise is to be able to boot up into a gaming-friendly environment with minimal fuss. Hook up a controller and you’re good to go. Support is also there for a few mobile devices, specifically some Aokzoe, Aya Neo, and OneXPlayer devices as well as some preliminary support for the Asus ROG Ally not to mention the Steam Deck as we touched on earlier. From a software perspective, it obviously supports the Steam platform but also Epic Games, Good Old Games (GOG), and tentatively a mention of console platforms. Sadly the website doesn’t mention much detail on that last bit, but there are some tantalizing hints in the project’s Twitter/X/whatever feed. Reading the release notes, there are mentions of PCSX2 (Playstation 2) Super Game Boy and Atari platforms, so digging into the GitHub repo might be instructive, or you know, actually installing it and trying. This scribe doesn’t own an AMD GPU so that isn’t an option, but do drop us a line in the comments if you’ve tried it and how it works for you.

Many of us at Hackday are avid gamers, especially of the retro kind, which is why we really like these projects. Here’s a nice game controller you can print yourself. For self-builds, there’s nothing quite like the satisfaction of a DIY arcade machine, but what if you think outside the box?

Hackaday Links: July 2, 2023

July 2, 2023 by Dan Maloney 21 Comments

Members of Pixelbar woke up to shocking news on Wednesday morning this week as they learned that a fire had destroyed the building housing their Rotterdam hackerspace. Pictures of the fire are pretty dramatic and show the entire building ablaze. We’re not familiar with Pixelbar specifically, but most hackerspaces seem to share space with other businesses in repurposed warehouses and other industrial buildings, and it looks like that was the case here. Local coverage doesn’t indicate that a cause has been determined, but they do say that “large batches of wood” were stored in or near the structure, which likely contributed to the dramatic display. There don’t seem to be reports of injuries to civilians or first responders, so that’s a blessing, but Pixelbar seems to have been completely destroyed. If you’re in a position to help, check out their GoFundMe page. As our own Jenny List, who currently lives in The Netherlands, points out, spaces suitable for housing a hackerspace are hard to come by in a city like Rotterdam, which is the busiest port in Europe. That means Pixelbar members will be competing for space with businesses that have far deeper pockets, so anything you can donate will likely go a long way toward rebuilding.

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An Entire RISC-V Operating System In 2000 Lines

May 18, 2023 by Bryan Cockfield 34 Comments

While Microsoft and Apple don’t release the source code for their operating systems, a good estimate is that it takes around 50 million lines of code to run these software behemoths. The Linux kernel alone holds around 30 million lines, with systemd containing over one million lines on its own, which doesn’t include estimates for the desktop environment or other parts of a standard installation. But millions of lines of code, or even hundreds of thousands, aren’t necessary for building a fully functioning operating system. This one sets up a complete OS in exactly 2000 lines of code.

Called egos-2000, short for Earth and Grass Operating System, the diminutive operating system is written for RISC-V computers and while it does contain most of the tools we would recognize in an OS, it was built specifically for computer science students by PhD candidate Yunhao Zhang. The slimmed-down operating system makes it possible for students to easily read and understand every feature of an operating system without it becoming too overwhelming, and can be easily used and modified to experiment with. The name itself comes from its design principles, where parts of the operating system that interact with hardware directly are part of the “Earth” layer and parts that don’t depend on hardware being placed in the “Grass” layer, with applications taking up a third layer.

The OS is available on this GitHub page under an MIT license and works on real RISC-V hardware as well as within various emulators. Building a complete operating system in so few lines of code is an impressive feat, and making it comprehensive enough to teach students with goes well beyond that accomplishment as well. Often when concepts in computer science are reduced to their bare minimum components, we end up with completely illegible (but interesting) experiments like this programming language instead.

A Collection Of Websites That Look Like Desktops

October 27, 2022 by Lewin Day 15 Comments

Web design has come a long way since those halcyon days of Web 1.0. There are plenty of rules about how to make a clean and efficient website, but sometimes it’s more fun to throw them out and just be creative instead. In that vein, [Simone] has curated a wonderful collection of websites that emulate the computer desktop experience online.

The collection’s website very much fits this theme. Upon visiting, an Award BIOS screen flashes up. From there, we get a Windows 95-like interface full of links to other sites that emulate a computer desktop layout. There’s even a 3D screensaver that pops up if you mouse away for too long.

There’s Browso.app, which semi-accurately tells you information about your computer in a theme reminiscent of MacOS 9. Meanwhile, clicking on “It Is As if You Were Doing Work” will take you to a weird game that’s compelling in its replication of office banality. Nightwave Plaza offers exquisite vaporwave vibes, while others simply intend to faithfully recreate various OSes in a browser window.

It’s a fun collection of websites that go from the weirdly afamiliar to downright impressive recreations of former realities. It’s certainly fun to click around for a while and see what’s out there. We do love some good web ephemera around these parts!

“Reversing Shorts” Demystify Phone Security

October 24, 2022 by Elliot Williams 3 Comments

Ever wonder what makes a cellphone’s operating system secure, or what that app you just installed is saying about you behind your back? In a brand new video series, [Jiska] gives us a peek into different topics in smartphone software reverse engineering.

For instance, her latest video, embedded below takes us through some steps to poke at Apple’s RTKit OS, which is the realtime OS that runs inside most of their peripheral devices, including AirPods, but also on their bigger devices too. We don’t know much about RTKit OS, but [Jiska]’s trick in this video is to get a foothold by looking through two different RTKit OS versions and noting which symbols are common — these are probably OS function names. Now you’ve got something to look for.

Each of the videos is short, to the point, and contains nice tips for perhaps the intermediate-to-advanced reverser who is looking to get into phones. Heck, even if you’re not, her demonstrations of the Frida dynamic tracing tool are worth your time.

And if you want a longer introduction into the internals of cellphones, we heartily recommend her talk, “All Wireless Stacks Are Broken“.

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