Abstract: Electronic lead determining circuitry operates to advantage with nonconstant relative movement between a paper record medium and an ink drop projector carrier of ink drop printing apparatus. Electronic lead determining circuitry is arranged for calculating the proper lead times for displacing the normal print enabling signals by factors dependent on the actual carrier positions and the lead for projecting ink drops at the desired positions.Ink drop printing apparatus of the type having a carrier bearing an ink drop projector across a record medium at a velocity relative to the record medium which may be varying substantially--either by design or unintentionally--, and bearing print position location detecting elements, and bearing ink drop projection controlling elements is perfected by controlling electronic circuitry for calculating lead time at a given print position for enabling printing at a predetermined designated print position precisely at the predetermined desired location on the paper.