Tonewheel organ for the M-VAVE FM-1, here in the browser.
Computer keyboard: the middle row plays the white keys, the row above the black keys, starting with A at the left C. Z and X (the bottom left keys: Y and X on a German keyboard) change the octave. USB MIDI keyboards are picked up if the browser allows it. setBfree's default controllers apply (CC 1, 7, 11, 31, 64 to 66, 70 to 78, 80 to 83, 92, 93, 95) and program change.
This page runs the same code as the FM-1 firmware (organ_core.h, built as WebAssembly), so it sounds like the firmware, apart from the FM-1's speaker and output stage. Whether the FM-1's processor can carry the load only the device itself shows.