Fedora Core seems to automatically enable OSS backward compatibility mode with ALSA sound. Mandriva 2007 doesn't. Possibly some other distros don't either, out of the box. If you have to do this manually, the trick is to do a "modprobe sound" as root. You need OSS compatibility for some older apps, such the "yae" Apple ][ emulator, that have not been updated for ALSA.