Rhythm — one bit turns three voices into five drums

6 Rhythm

One bit turns three of the melodic channels into a drum kit. Set bit 5 of register 0E and channels 7, 8 and 9 stop being melodic: they become five drums (Bass, Snare, Tom, Cymbal and Hi-Hat), each keyed by its own bit of 0E, voiced by fixed rhythm patches and a shared noise generator, and mixed a touch louder (+3 dB). Channels 1-6 stay melodic on the keyboard.

Arm Rhythm mode below, then hit the pads or run the demo beat. Each drum has a level (the 36–38 nibbles); watch them, and the 0E key bits, in the register file.

Where a drum comes from

The Bass Drum is just an ordinary two-operator voice on the ROM's bass-drum patch. The metallic voices are stranger: the Snare, Hi-Hat and Cymbal mix a 23-bit noise generator with fixed phase points to read pitched-yet-gritty tones, and the hi-hat and cymbal share a phase generator, which is why the cymbal's brightness depends on the hi-hat operator still running.