A marble computer that counts. Four tin rockers hang in a column, and every marble that lands on one flips it. A rocker showing 0 flips to 1 and sends the marble home; a rocker showing 1 flips to 0 and passes the marble down to the next. So the rockers count every marble in binary, while a tin bookkeeper keeps the same count on his abacus. Four marbles go round, so the red one comes every fourth count, and it always goes far. Stay for the end.

Every knock and every music-box note is timed by the machine itself.

After the Digi-Comp II's binary flip-flops.

Can you read the count off the rockers?