Control apparatus for serial printer

A serial printer comprising:

• a carriage;
• a print member rotatably mounted to said carriage and including a plurality of character elements;
• drive means coupled to said print member for rotating said print member to a desired rotational position in order to place a selected character element at a printing position adjacent a record medium to be printed upon;
• servo control means coupled to said drive means and responsive to a set of input data and instructions for generating a control signal to control the direction and regulate the speed of rotation of said print member in order to bring said selected character element to a stop at said printing position;
• and
• programmed data processing means coupled to said servo control means for supplying at least some of said set of input data and instructions under program control to said servo control means, said data processing means comprising a random-access-memory having a first addressable storage location for storing a first position signal indicative of the actual rotational position of said print member relative to a reference location and a second addressable storage location for storing a second position signal indicative of said desired rotational position of said print member, said first and second storage locations capable of being addressed under program control to provide said first and second position signals at the output of said random-access-memory, said data processing means further comprising an arithmetic logic unit responsive to said first and second position signals for calculating the clockwise rotational difference between said first and second position signals under program control, and means responsive to said calculated difference for supplying a command signal under program control to said servo control means, said command signal being indicative of a desired velocity of rotation of said print member for the particular distance remaining to be traveled by said print member until said desired rotational position is reached.