HelenOS is a microkernel-based multiserver operating system designed from scratch. By decomposing the operating system functionality into tens of isolated but intensively communicating userspace servers, it provides a computing environment that has several virtues such as flexibility, increased robustness, well defined explicit interfaces, and smaller complexity of individual components. HelenOS does not aim to be another clone of Unix or some other legacy system and is not POSIX-compliant (even though it may seem POSIX-similar at times). Instead, the goal has been to design it according to what is the most elegant and right thing to do. What makes HelenOS unique among the other multiserver operating systems is its multiplatform and multiprocessor microkernel. It will run on seven different processor architectures ranging from a 32-bit uniprocessor little-endian ARMv4 to a 64-bit multicore big-endian UltraSPARC T1.
mbldr (Master Boot LoaDeR) is a boot loader which fits into the first sector of an HDD (MBR). It allows the user to choose which partition to boot and is intended to replace an MBR that comes with DOS/Windows (fdisk /mbr). It may boot OSes above the 1024th cylinder, and Linux and BSD are also supported. mbldr is based on OS Boot Select (OS-BS) project by Thomas wolfRAM.
HeavenOS is an original, alternative 32-bit operating system for Intel 80386 compatible processors. It is made with NASM (The Netwide Assembler), and is not intended to compare to modern operating systems, but to try to get the best features and discover better ways to do things. It is intended to be a simple and pratical platform for development, running with a small amount of code.
MPEG Audio/Video Player is a simple MPEG and AC3 player for Linux, BSD, and Windows systems. It plays MPEG transport, program, and elementary stream files. It also has basic DVD support (using libdvdnav on Linux/BSD systems only). It features newly developed integer decoders for MPEG 1&2 video, MPEG layer 2 audio, and AC3 audio. It includes a partially working WMV/VC1 decoder capable of displaying I and P frames.
Coreboot (formerly known as LinuxBIOS) is a project that aims to replace the normal BIOS with a little bit of hardware initialization and a payload. Payloads can include a compressed Linux kernel, FILO, GRUB2, OpenBIOS, Open Firmware, SmartFirmware, GNUFI (UEFI), Etherboot, ADLO (for booting Windows and OpenBSD), Plan 9, or memtest86.
Buenos is a small SMP operating system skeleton that can be used as a base for operating systems project courses. The system is intended to be used as OS project base code which students can improve. Extensive documentation with suggestions for assignments or exercises is included with the system. It runs in a machine simulator called YAMS, which is its sister project.
Fiwix is an operating system kernel based on the Unix architecture and fully focused on being Linux compatible. It is designed exclusively for educational purposes, so the kernel code is kept as simple as possible for the benefit of students. It runs on the 32-bit x86 hardware platform, and is compatible with a good base of existing GNU applications.