FreeDOS, as the name implies, is a 100% free, MS-DOS compatible operating system. It extends on MS-DOS with a stack of extra tools that give you TCP/IP networking, remote file browsing tools, and stacks of other stuff. Version 1.1 is the first milestone release since 2006, and brings with it a stack of bug fixes and performance enhancements. http://www.freedos.org/ http://wiki.freedos.org/wiki/index.php/Main_Page FreeDOS is great for anything from flashing PC BIOSes off USB memory sticks to running old versions of MAME, to using inside a virtual machine (or even bare metal PCs) to play old DOS games. FreeDOS is used in the hugely popular DOSBox, and is also used by software publishers like GoG.