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.

[6] FreeDOS can be booted from a floppy disk or USB flash drive[7][8] and is designed to run well under virtualization or x86 emulation.

[2] 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.

The FreeDOS project began on 29 June 1994, after Microsoft announced it would no longer sell or support MS-DOS.

Jim Hall, who at the time was a student,[30] posted a manifesto proposing the development of PD-DOS, a public domain version of DOS.

[38] Furthermore, with the use of HX DOS Extender, many Windows Console applications function properly in FreeDOS, as do some rare GUI programs, like QEMM and Bochs.

Windows 3.x releases, which had support for i386 processors, cannot fully be run in 386 Enhanced Mode,[40] except partially in the experimental FreeDOS kernel 2037.

[45] Depending on the BIOS used, up to four Logical Block Addressing (LBA) hard disks of up to 128 GB, or 2 TB, in size are supported.