FreeDOS

FreeDOS (formerly PD-DOS) is a free software operating system for IBM PC compatible computers. It intends to provide a complete MS-DOS-compatible environment for running legacy software and supporting embedded systems. FreeDOS can be booted from a floppy disk or USB flash drive and is designed to run well under virtualization or x86 emulation. The FreeDOS project began under Jim Hall in 1994, and the first stable version was released in 2006. Unlike most versions of MS-DOS, FreeDOS is composed of free software, licensed under the terms of the GNU General Public License. However, other packages that form part of the FreeDOS project include non-GPL software considered worthy of preservation, such as 4DOS, which is distributed under a modified MIT License.