GB903656A - Electric signal generator - Google Patents

Abstract

903,656. Electric signal generators. INTERNATIONAL BUSINESS MACHINES CORPORATION. Jan. 16, 1961 [Jan. 14, 1960], No. 1691/61. Class 106 (1). An electric signal generator for removing time overlap from a sequence of time-overlapping pulses comprises coincidence gates' controlled so that alternate pulses are gated by the action of correspondingly alternate halfcycles of a controlling signal having a rectangular waveform. The described embodiment is concerned with record-card sensing apparatus in which cam-operated contacts R 9 - - - R 0 , R 11 , R 12 generate pulses in succession for sensing each row of a card. To eliminate overlap between these pulses they are fed to coincidence gates G, the other inputs of which are connected to alternate output leads 22, 23 of a trigger T so that the sequence of pulses arriving at output conductors D9... D 12 are non-overlapping (Fig. 2, not shown). In a modification (Fig. 3, not shown), only four cams instead of twelve are used and additional AND circuits are used to combine signals and their inverses to give the output signals at D 9 ... D 12 . The device is incorporated in apparatus for reading coded information from a record card 46 and storing it in a main magnetic core memory 42 in a different code from that used on the card. A single-shot generator 32 is switched on by a clock pulse from a timing signal generator 31 when a circuit-breaker Rz is closed. This causes a pulse generator 43 to apply a voltage to a roller 45, which is transmitted, through the perforations in a row of the card, to brushes 48, and changes the saturation in corresponding cores in a row of magnetic cores 49 of a buffer storage 41. When the generator 32 switches off, a scanning device 33 supplies successively all the positions in the buffer storage 41 and the corresponding positions in the main memory 42 with signals to control the transfer of information from the storage 41 to the main memory 42 through a transfer device 44 incorporating a coding device. When canning ceases a single shot generator 34 switches on, supplying a signal which is transmitted to the slow input of a diode gate 28 or 29 depending on whether trigger T is " OFF " (lead 22 energized) or " ON " (lead 23 energized). The next clock pulse from generator 31 reverses the state of trigger T. A coding device, as shown in Fig. 6, is incorporated in the transfer device 44 to change 12-bit card code into 7-bit memory code. As each core in the buffer storage is scanned by the device 33, a temporary storage device 60 records the information therein and also that in the seven cores of the corresponding location of the main memory. The presence of information in the buffer store causes a signal on line 1 to open corresponding gates E 8 , E 4 , E 2 , E 1 , E A , E B , E c , and information already in the main memory is passed via leads 1 B , 1 A , 1 1 , 1 2 , 1 4 , 1 8 , to a " write out " circuit 61. Zero coding apparatus 62, 63, 64 is provided to indicate whether a zero on the card is to be recoded as such or interpreted in combination with other numerals to indicate a letter or a special character. A parity check circuit is provided.