Time Twister 2: LEGO Mindstorms Clock
Each digit is made up of seven segments which are connected in a chain. The connections are made in such a way that a segment can be rotated 180 degrees before the next segment is affected.
By rotating the first segment a specific number of turns you can set the last segment in desired position. Then by rotating the first segment in the opposite direction a specific number of turns you can set the second last segment. By rotating alternately in one direction and the opposite direction, you can set all seven segments of a digit using only a single motor.