A logic for the recognition of printed characters employing a "proportional parts" method has been tested extensively by simulation. The proportional parts method relates the identity of a character to the relative size and position of character elements detected by optical scanning along closely spaced vertical lines. The video information from each scan c iosd ed to designate the number, size, and position of inked areas detected by the scanner. The time sequence or order of occurrence of this coded information is tested by logical circuitry against prescribed sequences for character recognition. A set of coding definitions, a prescribed sequence for the recognition of a given character, and the methods of simulative testing of the recognition logic on the IBM Type 650 Magnetic Drum Data Processing Machine are discussed.