- Website : http://cadcdev.sourceforge.net/softprj/kos/
- Author : Dan Potter, Lawrence Sebald, more
description taken from wikipedia
KallistiOS (KOS) is a free, BSD license-based development system for the Sega Dreamcast game console. The project was initiated in 2000 by Dan Potter, then garnering a team of free software developers over the Internet. Kallisti, from the Greek "to the fairest"; Kallisti OS (Operating System); or the abbreviation KOS, which is pronounced like "Chaos".
KallistiOS is the successor of libdream, the first free developer library for Dreamcast. libdream was also written by Dan Potter and published in mid-2000. It served as the basis of some hobby projects, but was soon replaced by KallistiOS. libdream source
KOS is the foundation of many, many games and app for the Dreamcast. Not only will it provide you with a unix-type filesystem, it will also handle maple I/O, SD card interface, graphics, sounds, etc.
KOS is considered to be the fastest way to get into Dreamcast development, but it comes with some drawback. It has a fairly large memory footprint (2-4 MB???) and isn't the fastest in term of graphics processing. Still, no other solution are as user-friendly (arguably, using Simulant could be considered as an alternative, although it is made using KOS)
KOS is itself a library, but it also prepare your computer to compile code for the Dreamcast as a target. In order to use KOS, you'll need to compile it from source. The process is quite straightforward.