What automatic drum machine did Leonardo da Vinci design to play music through rotating pegs?

Leonardo da Vinci designed a programmable drum machine that could play rhythms through rotating pegs.

The machine used a rotating cylinder fitted with movable pegs. As the cylinder turned, the pegs struck or activated mechanisms connected to drums. By changing the peg positions, an operator could alter the rhythm, making the device an early example of programmable mechanical music.

The design reflects Leonardo's interest in automation, gears, cams, and repeatable motion. It was not a digital computer and did not store music as modern data. Its program was physically encoded in the placement of mechanical elements on the cylinder.

The machine is sometimes grouped with Leonardo's famous mechanical robot because both belong to his studies of automata. They are distinct designs, however: the robot was a human-shaped automaton, while this device was a musical mechanism. Reconstructions have been made to demonstrate how its rotating-cylinder control could work.