Sinistar was a game that had quite an impressive sound design. It borrowed a bunch of its sound effects from earlier Williams games, with which it shared common hardware that was originally design for pinball machines. A cockpit version of Sinistar, of which only around 200 units were made, was the first arcade game to have stereo sound. And of course all versions of the game have the Sinistar’s famous digitized threats and taunts.
While Sinistar’s main program source code was found and made available on Github, the source of the code that drove its sound hardware has long been lost. Youtube user SynaMax has done the best he could at recreating that code, and has made a video talking about the process, the sound design of Sinistar and other early Williams games, and even found unused sounds in the code.
Contained within the code is the revelation that the sound chip that drove the rear speakers in the cockpit version ran slightly different code than contained within the main sound ROM. The data from that version of the game was only dumped this year, meaning that the game running in MAME was somewhat incorrect.
Now that the right version of the chip has been dumped, the cockpit version of Sinistar now sounds properly in MAME. Although this does mean that users running up-to-date MAME have to refresh their romset for this version of the game. Such are the tradeoffs of MAME emulation.
Another revelation of the video was that the parametric sound generators used by Williams arcade games from that time often produced interesting noises if it was fed with random data. Sound programmers sought out different sets of numbers to give them, including by asking passers-by for numbers off the top of their heads and garbage values found in RAM when dev systems were powered up, in order to produce strange sound effects.
I feel like I should warn however, near the end of the video is mention of a bit of drama concerning the MAME developers, in getting code supporting the change integrated into the software. I’m not weighing in on this, not the least reason being I don’t know enough about it. But I feel like you should know it’s coming, ahead of time, before embarking on the 51-minute journey.
Rescuing the Lost Code and Stereo Sound to Sinistar (Youtube, 51 minutes)