EmuTOS is a free operating system for computers based on Motorola 68000 or ColdFire microprocessors. It features functionality similar to TOS, which powered the Atari ST and its successors between 1985 and 1994. EmuTOS can run on real hardware, either as ROM replacement or from floppy. Of course, it also runs on any Atari emulator such as ARAnyM, Hatari, or Steem SSE. Just like TOS, EmuTOS is a small but complete single-tasking operating system. To go further, EmuTOS can be used as a stub to run FreeMiNT, a much more powerful multitasking kernel. Coupled to emulators, EmuTOS and FreeMiNT provide a completely Free environment to run modern Atari software. The EmuTOS project started in 2001, and it is still actively developed. Some parts come from old open-sourced code from Digital Research, while some other parts have been developed from scratch.