Today I've been working on a setup whereby an iPod Touch / iPhone running TouchOSC can sequence and manipulate the drum channels from a YM2413 inside of a Sega Master System.
I would have simply made my own patch for TouchOSC, but I was having some troubles uploading it to my iPod, so I simply mapped data from the default 'Beatmachine' template.
The following parameters can be changed from the iPod Touch:
• Rhythmic sequencing
• Step-wise pitch sequencing
• Global pitch transposition
• Global note length
• Individual drum volume control
Here is the mapping at the moment. I am hoping to add a 'loop' save / load type mapping, where the user can build up a loop, save it, change the loop until it is a different thing entirely, and then come back to original easily (with 9 such 'save slots' available).
The YM2413 has five basic drum sounds, kick drum, snare drum, tom, hi hat and cymbal.
In the video below, the only effect that has been added to the direct output from the Sega Master System is a bit of a delay line. All other changes in sound are a result of changing the parameters of the sequence or changing the parameters inside of the YM2413.