In short: OSS was very well known. But then ALSA came and kicked OSS's butt and nobody wanted OSS anymore. But some people developed it outside the linux kernel and is available for download.Code:In the Linux kernel, there have historically been two uniform sound APIs used. One is OSS; the other is ALSA (Advanced Linux Sound Architecture). ALSA is available for Linux only, and as there is only one implementation of the ALSA interface, ALSA refers equally to that implementation and to the interface itself. OSS is the standard up through the 2.4 series of official (kernel.org) Linux kernels. ALSA was added starting with 2.5, and in those versions, Linux kernel authors marked OSS as deprecated. 4Front continued to develop OSS outside of Linux kernel. ALSA provides an optional OSS emulation mode that appears to programs as if it were OSS. Similarly, there is an ALSA emulation mode in the Linux implementation of OSS. While some recommend the ALSA interface for software that is intended to work on modern Linux only, software intended to be portable across Unices typically uses OSS instead. Another advantage of OSS is the fact that it's better documented than ALSA and the API is much simpler.