A 3 channel sequencer, with some interesting features

Three independant rows of sequences, running at the same clock.
Each step has a 3 position switch that determines how that step is played; Normally, as that channels reset point, or as the point from which the channel begins to play backwards in "Ping-pong' mode.
The sequencer has an internal oscillator for tempo, but can also be clocked from an external source. A master switch determines whether the sequence plays forward, in reverse or randomly.