Patent GB-876405-A (GB)
Title: Improvements in code detecting devices for data reading apparatus
IPC: G06F3/06
Filed: 1958-01-22
Abstract: 876,405. Detecting apparatus for coded signals. INTERNATIONAL BUSINESS MACHINES CORPORATION. Jan. 22, 1958 [Jan. 22, 1957], No. 2184/58. Class 40(3) A code-detecting device for data-reading apparatus adapted to read characters serially from a record and to produce corresponding combinations of electrical signals representative of such characters comprises a code analysing device having a separate output terminal corresponding to each of two or more predetermined characters and being arranged to operate and energize the corresponding terminal in response to the signal combinations representing one of the said predetermined characters, separate control means connected to each output terminal and arranged to indicate directly for some of the terminals whether the associated output terminal has been energized, and providing such indication s for the remaining terminals in dependence on a predetermined sequence of the combinations of signals corresponding to the remaining terminal s, and means for examining the indications from said control means and producing an output according to the result of such comparison. Diagrammatic arrangement, Fig. 1. A tape 12 perforated according to the 5-unit code is passed through a tape-sensing unit 10 providing pulses for a device 16 which may be a printer, cardpunch, or a magnetic store, and also pulses to a code analyzer 14 which produces pulses on outputs 18, 20, 22 in response to carriage-return (CR), figure-shifts (FS) and line-feed (LF) signals respectively. The signal on the conductor 18 is applied to a control circuit 24 and the figure-shift signal on the conductor 20 operates a primary control circuit 32 and a further control circuit 26 passing a signal to the control circuit 30 which has already received a signal from the circuit 24. If the C.R. and F.S. signals have been received in sequence, the pulse on conductor 22 in response to the LF signal operates circuit 30 so that the line-feed control circuit 28 passes a pulse to the analyzing network 34 which has also received pulses from the circuits 24, 26. A further pulse from the circuit 28 conditions a comparison or detector circuit 36 so that a pulse cannot be passed to an error-indicating circuit. If the three signals CR, FS, and LF, have not been received in sequence, the circuit 36 is able to pass a pulse to the error circuit 40 providing an output which may be utilized to arrest the tape-sensing unit so that correction can be effected. Detailed circuit arrangement. Figs. 3, 4. Operation is initiated by the closure of a switch 47, Fig. 3, energizing a relay 46 which locks over its H winding and a contact A closed by a cam 50 in parallel with A of a relay 48. The beginning of a unit record is signified by a figure shift (FS) signal which through the analyzer 14, Fig. 1, produces a pulse on the line 20 which does not energize FS1 relay 56 since contact A of relay 58 is open, but relay 48 is energized through the closed A contacts of relays 58, 60 and locks up over its contacts B. Relay 48 opens the circuit of relay 46, which later releases, and operates relay 58 at which contact B prepares a circuit for the operation of the FS1 relay 56 when a pulse appears on line 20 in response to the FS signal. During the reading of the data the relay 56 is operated by the FS signal which is not effective in the detecting circuits. When the first signal, i.e. CR, of the end-of-unit code is received, an impulse on line 18 operates CR-1 relay 72 which locks up over its A contact and during the reception of the second signal, i.e. FS, the CR-2 relay 74 operates over the B contact of relay 72 and locks up over its A contact. Also the FS-1 relay 56 is operated and locked up and later in the second signal cycle the CR-3 relay 76 is operated over contacts A, B of relays 77, 74 respectively and locks up over its A contact. During the third cycle when the signal LF is received, CR4 relay 78, energized over contact B of relay 76 and contacts closed by cam 79, is locked through its own contact A and cam 50, whilst FS-2 relay 80 is operated over contacts C of relay FS-1 and those closed by cam 79. Relay 82 is energized over the operated contacts of relays 78, 80 by the impulse on conductor 22 in response to the LF signal is held by its A contact and that closed by cam 50. Relay 70 also operated from operated contacts of the relays 78 and 80, looks up and operates relay 46 which locks up until relay 48 is actuated in combination with the opening of contacts by the cam 50. Relay 46 also opens the circuit of relay 58 which releases. If the three signals CR, FS, LF have been correctly received, contacts 68 closed during the LF signal cycle are unable to operate error relay 86 since the contacts B of LF relay 82 are open. The signal cycle following those of the signals CR, FS and LF effects the operation of relays 60, 88 for checking the signal tape, as referred to in Specification 843,004, and subsequently an end-of-message code or single FS signal determine the machine operation. Operation in response to incorrectly received code. If the signals CR and LF are received, but FS is missing, relays 72, 74, 76, 78 are operated, but relay 82 cannot be energized. Relay 77 is energized from conductor 22 via rectifier 85 and a circuit is completed for error relay 86 which may be employed to stop the operation of the unit 10 or to decouple the device of the assembly 16. Similarly, where solely the CR signal is missing, a signal in conductor 22 operates relay 77 which operates error relay 86. In other cases where the combination CR and FS, or solely CR is received, the relay 77 is energized and accomplishes the operation of error relay 86. Simultaneously with the operation of relay 86 a potential is available at the terminal 96 and can be employed to effect control functions as described in Specification 690,852.