815,066. Sensing characters photo-electrically. INTELLIGENT MACHINES RESEARCH CORPORATION. Aug. 15, 1955, No. 23390/55. Class 40 (3). Legible characters are sensed giving signals which are detected and interpreted in accordance with the occurrence of basic shapes and sequences. The sheet of characters 20 is scanned by a cathode-ray tube 23 controlled and gated by a clock pulse generator 35 to produce two vertical lines of scanning light spots sixteen in each line. The light received by photo-cell 21 gives a signal which is amplified and clipped and fed through a gate 38 to a recognition pulse counter 40 (Fig. 3, not shown) recognizing a negative signal of high amplitude synchronously with a pulse from clock pulse generator 35. The latter pulses feed the Permanent Memory 33 which gives " scale of 2 " and " scale of 32 " pulses to the line and frame sweep generators of the cathode-ray tube. Non-recognition pulses R o of positive sign are derived by an inverter 39 from the signals of low amplitude at the photocell and fed to the plug board 33 of the Permanent Memory. Every second pulse from generator 35 gates counter 40 so that it counts only recognition pulses in one vertical scanning line. The count is made by flip-flop triodes in four stages, with a maximum scale of 8. A reset circuit is triggered by a non-recognition pulse R 0 in coincidence with a double synchronizing pulse. The number of successive recognition pulses is counted and the result fed to a comparator or Decision unit 55 comprising a number of comparator or " and " circuits (Fig. 4, not shown). The information is fed to a temporary memory 65, comprising three units, namely, a priming stage 66, a shape memory stage 67 and a pulse shift register 80, determining whether or not any of a series of relays are operated by the information and finally erasing. Storage may be by vacuum tubes, a magnetic drum, magnetic binaries, cathode-ray tube, delay lines or relays, but is preferably a number of thyratrons. The priming thyratron has a diode connected between its cathode and earth and a turn-off pulse input also coupled to the cathode receiving " end of frame " or " end of character " pulses from other parts of the apparatus (Fig. 5, not shown). The shape memory stages comprise thyratrons with their anodes connected to the shape relays 86-93 and to the end of character reset relay 95. The pulse shift register comprises an amplifier associated with a series of one-pulse delay stages and clipped amplifiers giving a source of delayed recognition pulses determining coincidence in certain conditions. The output of the temporary memory feeds to a bank of relays comprising a storage unit, with eight routing coils 86-93 associated with contact arms 86a-93o, the relays being operated by the various combinations in the firing of the shape memory stages 67. The combinations of relay operations detecting a particular numeral are indicated by the outputs 0-9. For example an output detecting the numeral 6 has coils 89, 86 energized and 88 and 90 not energized. The programming of the priming stages P 1 -P 8 , P E and of the shape memory stages M 1 -M 8 in accordance with the reception of clock pulses a and b, recognition and non- recognition pulses R o and R o necessary for the particular recognition of shape, is given in Fig. 10, the shape-identifying characteristics of certain numerals being shown in column 112. The sequences of operation of the various stages are explained in detail in the Specification. The apparatus is stated to be applicable also to the reading of alphabetical characters and punctuation marks.