Instrument — the patch, and the fifteen in ROM

4 Instrument

Everything so far (the two operators, their Multiples and levels, both envelopes, feedback, the waveforms) is eight bytes: a complete OPLL patch, registers 00–07. You get one such user patch to edit; the other fifteen instruments are fixed in ROM. That constraint is what defines the chip.

Pick a ROM instrument from the gallery and play it; each tile shows its harmonic fingerprint. Then hit copy → user ✎ to drop that ROM's eight bytes into your editable slot, and the same sound becomes yours to take apart. The fixed ROM stops being a limitation and turns into a starting point.

Slot 0 is special

Instrument 0 on any channel means "use the eight user bytes"; 1–15 select a ROM patch. The operator controls here always edit the user bytes. While a ROM instrument is selected they are shown for reference but change nothing, which is why copy → user exists.