256boss - USB-bootable OS to run 256byte intros like a boss



256boss is a standalone USB-bootable operating system for running 256byte intros without having to install DOS. It's based on the pcboot project.

256byte intro compos rapidly devolve into an emulated category on recent demoparties, making dosbox into its own platform, due to the disproportionate hassle of setting up a computer with MS-DOS or FreeDOS, just for the task of running 256byte intros.

As a result of this emulationization of 256byte compos, signs are appearing of entries requiring specific dosbox "cycles" to run properly, or using a wide variety of sound hardware emulated by dosbox, without regard for what a realistic compo PC would have, and having to contend with that like every other category.

We at mindlapse demos feel this to be a travesty, and cannot allow this slippery slope to continue. For this reason we decided to create 256boss: a simple and painless way to run 256byte intros on real computers, without any hassle other than inserting a USB stick, rebooting, and possibly selecting the USB stick from a boot menu.

Use it to watch 256byte releases at home, or use it to run a 256byte compo at a demoparty. Just install 256boss on a USB stick, by following our simple installation instructions for each platform, copy every 256byte intro you want into it, and reboot.

Github project page: https://github.com/MindlapseDemos/256boss


Copyright (C) 2019-2020 John Tsiombikas <nuclear@mutantstargoat.com>

This program is free software. Feel free to use, modfy and/or redistribute it under the terms of the GNU General Public License v3, or at your option, any later version published by the Free Software Foundation. See COPYING in the source archive for details.


Unless you intend to get involved in the development of 256boss, just grab the latest "official" release, which includes everything you need to get up and running.

The official releases are available in gzipped-tar, or zip archives. You just need one or the other; they are identical. If you don't know which one to get, you should probably get the zip file.

256boss latest release (v0.1):

Github mirror:

Although the official releases do contain the full source code, if you intend to contribute to 256boss, you should get the latest code directly from our git repository on github: git clone https://github.com/MindlapseDemos/256boss.git

Setup instructions

The 256boss release comes with a pre-generated bootable disk image, ready to be written onto a USB stick (if you got the source code from github instead of an "official" release, follow the build instructions in the next section first). The disk image contains both the boot loader and operating system itself, as well as a small FAT partition where you can store your 256-byte intros to access them when you boot 256boss.

Windows setup

To install from Windows, insert a USB stick, and run the install.bat batch file. This will start the bundled "rufus" program with the 256boss disk image already loaded. Just make sure the correct USB device is selected and click "start".

win setup

GNU/Linux setup

To install from GNU/Linux, insert a USB stick, and identify which device file corresponds to it by running lsblk, or monitoring dmesg. For the purposes of this example we'll assume the USB stick device file is /dev/sdc; make sure you replace the correct one. Run dd if=disk.img of=/dev/sdc bs=1M to install.

GNU/Linux setup

Reboot to start 256boss, and make sure to boot from the USB stick. Some computers will boot from the USB stick automatically, while others require you to press a key (usually ESC, F8, or F12) to pop up a boot selection menu. Watch the screen during POST, where a message will most likely appear instructing you which key to press. If you're still having trouble booting from the USB stick, make sure legacy boot is enabled in your BIOS settings.

Build instructions

Just run make.

To test the build in an emulator, make sure qemu for i386 is installed, and invoke make run.

If you're trying to build the source code from git, make sure to first copy over the data directory from an official release.

Tools compiled as part of the build process require libpng, and zlib


You will most likely encounter two forms of bugs:

Ideally I would like to eliminate both of these problems. And while I can't promise that 256boss will ever be 100% compatible with every computer and every intro out there, I would appreciate reports of any such bugs you encounter, either by email, or preferably by opening an issue in the project issue tracker on github.

For computer-compatibility bugs make sure to include as much information as possible about the nature of the problem, and about your computer. Most relevant is going to be the computer manufacturer and model (if applicable), CPU, motherboard, and BIOS version.

For intro-compatibility bugs, first make sure the problem persists even when the intro in question is executed directly after booting into 256boss, without having ran any other intros previously. This is important, because prior intro executions might lead to subtle corruption that will make a subsequent intro (or the operating system itself) fail. If possible, try to run the intro in MS-DOS or FreeDOS on the same computer, to make sure the bug is in 256boss and not in the intro itself.


If an intro fails to run correctly under MS-DOS or FreeDOS in a certain computer, it will probably also fail to run under 256boss.

If an intro needs an adlib card to play music, and your computer doesn't have an adlib card, 256boss will not emulate one. You need the hardware the intro is written for; 256boss is not an emulator like dosbox.

If a computer is UEFI-only and cannot boot in BIOS (or "legacy" mode), 256boss will not boot. It's unlikely for this limitation to be lifted any time soon.