Digital image overlay system and method

摘要: A data processing system includes, among others, three memory areas: a source which is addressed in planar, unit increments and stores display units on bit per plane basis; target for storing manner suitable operation of unit; window buffer transferring from the to memory. The includes apparatus inhibiting certain overwriting already method comprises first accessing plurality then logically determining if all bits each accessed meet predetermined criteria. Each found criteria inhibited altering any