Patent GB-786029-A (GB)
Title: A magnetic data storage verifying means
IPC: G06F11/16
Filed: 1950-06-23
Abstract: 786,029. Data verifying apparatus. DIRKS, G. June 23, 1950 [Oct. 1, 1948], No. 37210/54. Divided out of 786,021. Class 106 (1). Means for verifying stored data comprises a magnetizable layer for the storage of characterrepresenting signals, and transducing means for sensing two recordings of the information to be verified and comparing them character by character. In a first embodiment an electrically-controlled typewriter, Fig. 1, including printing mechanism 2 which may be of the type described in Specifications 786,022 or 786,024, [both in Group XVI], comprises two magnetizable tapes 4 and 5 on which data entered from the keyboard 1 may be recorded. When used for verifying, the second tape normally, would be recorded by a second operator and then compared automatically with the recording on the first. Alternatively, the second recording may be made on another part of the first tape or in some other storage. Other uses of the two tapes are described in Specifications 786,031 and 786,034. Details of the feeding and sensing arrangements of the two tapes are described in Specification 786,031. The digital data may be represented by single magnetic signals of a certain direction and amplitude, or by a certain sequence of frequencies or interruptions of a basic frequency, or a phase shift. Figs. 2b to 2p illustrate the various forms suggested. A zero or datum position may be established by a perforation, e.g. the feed holes 22, Fig. 3, or a magnetic signal. The arrangement of signals on the tape and the code used, are shown in Figs. 3 and 4, respectively. A complete " unity " of data would normally comprise eighty columns-equivalent to a standard record card. An assembly of fifteen magnetic heads 25<SP>9-0</SP>, <SP>a-e</SP> is used for reading data from, and writing signals on to, the tape. The heads may be moved relatively to the tapes, with intermittent feeding of the tape, as described in Specification 786,031, or the tape may be moved relatively to fixed heads. Other arrangements such as transversely-moving heads, are mentioned. Recording on the tape. To record a symbol in one column of a tape one or more switches 45<SP>9</SP> ... 45<SP>e</SP>, Fig. 6, are closed by depression of one of the keys 1, Fig. 1. A winding 49, Figs. 6 and 7, on a U-shaped core 51, is energized by current from terminal 44 passing through a closed switch 54, resistor 27 and winding 49 to terminal 43. When a tooth 48 on a rotating member 47 passes close to the core 51 a voltage is induced in the secondary winding 50 sufficient to fire the gas tube 52 and so provide a path for magnetizing current through the selected head or heads 40<SP>9</SP> ... 40<SP>e</SP> and so record the appropriate signal in the first column position on the tape. This recording occurs during a relative movement between the tape and the recording heads covering a complete " unity " comprising eighty column widths. Since the rotation of the member 47 is synchronized with this relative movement, the " column " in which the recording is made is determined by the position of the core assembly 49-51, which will, therefore, be moved angularly between each recording to determine the position of the next recording. A relay 53 opens contacts 54 to de-energize the winding 49 after each recording pulse. Instead of moving the core assembly 49-51, eighty similar devices could be arranged in appropriate angular positions and selectively brought into operation (see Fig. 8, not shown). Comparing means. A reading head 141, Fig. 11, senses the original recording while a second head 144 senses the second recording, and respective pentodes 145 and 146, connected in push-pull, are influenced accordingly. If signals are detected by both heads simultaneously no voltage is induced in the secondary winding 148 of an output transformer. On the other hand, if only one of the heads 141, 144 detects a signal, a voltage will be induced in the secondary winding 148 which will fire a gas tube 149 and actuate a relay 150, indicating disagreement. Such a device could be used for group control and also for checking the operation of a computer by comparing the recorded results of successive computations of the same problem. Specifications 786,030. 786,033, 786,037, [Group XVI], 786,039 and 786,046 also are referred to.