United States Patent Office
John L. Hill, North St. Paul, Minn., assignor to Remington Rand Inc., New York, N.Y., a corporation of Delaware
Filed May 20, 1954, Ser. No. 431,108
14 Claims. (CI. 340—174.1)
This invention relates to methods and apparatus for storing and reproducing information or the like. The invention is best illustrated in connection with magnetic recording on the surface of synchronously rotating drums, and the following explanation will proceed in regard thereto. However, the invention is equally applicable to non-magnetic recording and may utilize drums, disks, endless tapes or reeled up tapes as the recording medium.
In U.S. Patent No. 2,540,654 issued February 6, 1951, to A. A. Cohen et al., there is described apparatus for recording magnetic spots or cells on the surface of an elongated magnetizable member which is adapted to be moved continuously in relation to various magnetic transducing heads. In a specific embodiment therein disclosed, the magnetizable surface is in the form of magnetic tape which is wrapped tightly about the periphery of a rotatable drum. The patent describes how so-called binary magnetic spots, that is, spots having flux oriented in one of two possible directions, may be recorded upon, removed from, and altered in the message or intelligence tracks of the drum. It is also explained how a series of flux notation of the same character may be blended into one another to form a continuous flux field in one direction. This has been referred to as non-return-to-zero recording. However, so-called return-to-zero recording may be employed, wherein the spots of flux are discrete even if a series of spots along a track happen to be of the same character.
Various techniques for locating specific cells or areas in the intelligence tracks for a reading, recording or selective alteration operation have been described in the above mentioned Patent 2,540,654 and in improvements thereon; for instance, U.S. Patent No. 2,614,169 issued October 14, 1952, to A.A. Cohen et al.; application of A. P. Hendrickson et al. filed December 30?-1950, Serial No. 203,612, now U.S. Patent No. 2,771,595, issued November 20, 1956; and application of H. L. Daniels et al. filed February 26, 1952, Serial No. 273,490, now U.S. Patent No. 2,680,239, issued June 1, 1954. In each of these patents and applications, the locating techniques described require the use of address or identifying information in additional tracks and/or memory devices.
This invention is based upon the techniques described in the above-cited Patent 2,540,654 and relates in particular to the use of such techniques for the storage of messages of more or less uniform length or lengths. The techniques described in connection with this invention disclose means for locating a specific message by utilizing a unique identifying criterion forming an integral part thereof, which criterion may be either an inherent portion of such message or supplied thereto for locating purposes. This disclosure demonstrates how such messages may be arranged on the surface of the drum to allow the location of a specific message in a minimum of time, while retaining economy in the amount of circuitry and number of additional drum tracks required. Since the criterion will ordinarily be a fundamental element of the
message, as where account entries are recorded with the customer's name or where time of aircraft departure is reserved by plane or flight number, no decrease in storage capacity of the message tracks is involved.
5 It is accordingly an object of this invention to provide an improved system for storing messages on the surface of a cyclically moving record member.
It is a further object of the invention to provide methods and apparatus for locating specific messages on the
10 surface of a record member.
Further objects and advantages of the invention will be apparent from the following description and accompanying drawings, in which:
Figure 1 is a diagrammatic layout of the invention.
15 Figure 2 illustrates a ring counter which may be employed in the invention.
Figure 3 is a schematic drawing of an electronic switch and a reading amplifier employed in the invention. Figure 4 shows a coincidence detector circuit used in
20 the invention.
Referring now to Figure 1, showing exemplary structure, the numeral 10 designates a movable record member comprising a drum having a magnetizable surface. Recorded on message tracks 12, 14, 16 and 18 on the
25 drum are a series of data groups, information or messages, each of which contains a unique identifying portion or criterion, designated in the drawing as C, followed by satellite information designate S. The tracks 12, 14, 16 and 18 comprise one block of message tracks. It
30 will be understood that the identifying criterion can be part of t ie data group if desired. In practice there would ordinarily be a great many blocks of tracks. While the criteria of the messages need not be uniform, the space reserved therefor in each message must be
35 constant. The messages may be coded in ordinary 5-unit Teletype code and recorded serially in a continued string of cells or characters along a single track of the drum with the fifth bit of each character immediately preceding the first bit of the next character. Recording may be ac
4° complished by means of writing windings on transducers 29, 22, 24 and 26 positioned adjacent the message tracks. Means for recording are described in the above-cited Cohen et al. Patent 2,540,654.
Three drum tracks are provided for control purposes.
45 Track 28 contains a series of permanently recorded criterion marks, equally spaced by exactly the number of cell or character spaces reserved for the criterion of a message. The second control track 30 contains a single, permanently recorded reference mark 32 which is aligned
50 with one of the criterion marks 34. When alignment of marks or cells between two different tracks is considered, this is not necessarily meant to indicate physical alignment, because the close spacing of adjacent tracks may require that the relatively large transducing heads
55 be arranged helically around the drum as shown in the above-mentioned Cohen et al. Patent 2,540,654 or otherwise staggered about the periphery of the drum. Therefore, the marks, cells and/or characters will be considered according to their "electrical" alignment and are
6q so depicted to the drawing.
The third control track is revolver track 36 with which is associated a writing or recording transducer 38, a reading transducer 40 and an erase head 41. Pulses recorded on track 36 through writing transducer 38 are played back by reading transducer 40 after the drum rotates through a distance equal to that between adjacent criterion marks on track 28. The pulses are immediately rewritten on track 36 and so are kept in continuous recirculation until the recirculation path 42 is
»0 interrupted by switch 39. The elements operative in the recirculation of these pulses will be referred to as the revolver means. In capacity operation, the total number