Gujin is a PC boot loader that can analyze your partitions and filesystems. It finds the Linux kernel images available, as well as other bootable partitions (for *BSD, MS-DOS, Windows, etc.), files (*.kgz) and bootable disk images (*.bdi), and displays a graphical menu for selecting which system to boot. It boots the Linux kernel using the documented interface, like LILO and GRUB, so it doesn't need any other pre-installed bootloader. It can also directly load gzipped ELF32 or ELF64 files, with a simple interface to collect real-mode BIOS data. There is no need to execute anything after making a new kernel: just copy the kernel image file into the "/boot" directory, with a standard name. Gujin is written almost entirely in C with GCC, and it fully executes in real mode to be as compatible as possible.
iPXE is a network boot firmware. It provides a full PXE implementation enhanced with additional features such as the ability to boot from a Web server using HTTP, and the ability to boot from a SAN using iSCSI, AoE, SRP, or FCoE. It supports a wide variety of network devices, including wireless and Infiniband networks. iPXE is an effective replacement for gPXE.
GRUB for DOS is a rebuild of the GNU GRUB boot manager for DOS, and can be run under real mode DOS. It also has many new features. It can be booted through BOOT.INI of Windows (grldr) and kexec of Linux (grub.exe). It can directly boot NTLDR (WindowsNT/2K/XP), IO.SYS (Windows9x/Me) and KERNEL.SYS (FreeDOS). The disk emulation feature is another enhancement over GNU GRUB, and can be used to run legacy DOS/Windows9x systems with floppy or hard disk images.
The Google Serial Graphics Adapter BIOS, or SGABIOS, provides a means for legacy x86 software to communicate with an attached serial console as if a video card were attached. It is designed to be inserted into a BIOS as an option ROM to provide over a serial port the display and input capabilities normally handled by a VGA adapter and a keyboard, and additionally provide hooks for logging displayed characters for later collection after an operating system boots. It is designed to handle all text mode output sent to the legacy video BIOS int 10h service routine. Int 10h is the most common method for displaying characters in 16-bit legacy x86 code.
GAG is a Graphical Boot Manager with a lot of features. It doesn't need a partition, it works with primary and extended partitions in every hard disk, it has a lot of icons, it allows you to put passwords for each operating system, it can swap hard disks and it can be tested from diskette. The SafeBoot feature allows you to boot your hard disk even if GAG is overwritten. It includes extensive support for many languages and keyboard types.
GNU GRUB is a Multiboot loader. It was derived from GRUB. It is an attempt to produce a bootloader for IBM PC-compatible machines that has both the capability to be friendly to beginning or otherwise non-technically interested users and the flexibility to help experts in diverse environments. It is compatible with FreeBSD, NetBSD, OpenBSD and Linux. It supports Windows 9x/NT/2000/XP and OS/2 via chain-loaders. It has a menu interface and a command-line interface.
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.