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What kind of mechanism is used in a date dial on a watch?It stores tension, moves a disc a set amount - not gradually. Answered

I've looked high and low, but can't find a description of the date dial mechanism.  Unlike hte hour hand or the moon dial, it doesn't move gradually - it moves a set rotation percentage,  all at once, so exactly one number is displayed at any given time, and at midnight, it switches over. 

Does this make sense?  Does anyone know about this mechanism?  What are the components?

I'm trying to create an analog random story generator, using the same principal as the date dial on a watch.  Instead of numbers, the discs will have pieces of a narrative written on them.  Each one will rotate at a different rate, and each disc will be divided into sections with once sentence each.   The intention is to hide all but one sentence behind a board, with a window cut out to display the one.  A drawing would make more sense. 


My watch moves over about 1/2 an hour - as Foolish suggests a geneva mechanism will do the trick.

A clock work generally uses and Escapement and gears to regulate the movement of hands etc.

The geneva mechanism allows for discrete steps. You can google it easily for examples.