They appear to be aware of this bug and it might get fixed in the next version. But the real fix is downloading Yabause version 0.9.12, which had a working OpenGL mode on OS X.

Then if you go to fullscreen, it crashes the emulator. The software graphics renderer is not fast enough to be playable with frameskip turned on, the game is playable, but you wouldn’t want to. The third option is the “Grand Central Dispatch” graphics driver, and this actually works well. With the current version (0.9.13) the OpenGL graphics renderer shows no graphics at all (just a black screen with audio). Audio just works, and there’s nothing to change. Also uncheck the box for “Enable BIOS emulation” unless you were unable to find a copy of this BIOS file anywhere. The first thing to do is to open Preferences, and point it to the location of your Sega Saturn BIOS file. With a game ISO (original disc in your system, or disc image – see my earlier post on imaging your original discs), and a Sega Saturn BIOS file, you are good to go. It builds on Mac OS X and even ships an OS X binary, in an app bundle too! You won’t need much help getting it to work. The Yabause emulator carries the torch now. They have all been abandoned (or in the case of Giri Giri, sold to SEGA). There were a string of Windows-only closed-source emulators, including SSF, Giri Giri, Satourne, etc. It was expensive, hard to program for, and its graphical abilities were best suited to 2D. Before the days of multi-core processors, parallelism meant having multiple chips. The SEGA Saturn was long said to be impossible to emulate, because of its unusual (ridiculous) architecture that incorporated eight processors (two Hitachi SuperH SH-2 processors, one Hitachi SH-1 processor just for streaming and decompressing from the disc in realtime, two “video display processors” from SEGA, a Motorola 68EC000 for sound, another custom SEGA DSP chip for sound built by Yamaha, and finally something called the System Control Unit).

How to use mame emulator mac