Patent GB-820115-A (GB)
Title: Improvements in storage devices for signals
IPC: G11B21/10
Filed: 1955-12-09
Abstract: 820,115. Electric digital-data-storage apparatus. DIRKS, G. Jan. 15, 1957 [Dec. 9, 1955], No. 35358/55. Class 106 (1). A selective signal store (e.g. for a computer) comprises a frame with a plurality of rotatable discs mounted therein each having a signal storage surface on at least one face, means for sensing, recording, and erasing signals, means for effecting relative movement between the frame and the discs, and control means for selecting signals for sensing, erasing, or recording during a phase of this movement. Arrangement of discs. Both sides of each of the discs 3<SP>1</SP> ... 3n, Fig. 1, are available for storing information, double read/record heads 52, 53, &c., being supported between each pair of discs on arms 6<SP>1</SP> . . . 6n rotatably mounted on a shaft 8 controlled through an arm 11. The arm 11, Fig. 3, is linked to a cam disc 20 which can be rotated by a motor 24, the energizing circuit for which is under the control of a number of normally open contacts 28<SP>1</SP> ... 28<SP>n</SP>, in parallel, each of these being in series with an associated one of a number of contacts 25<SP>1</SP> . . . 25<SP>n</SP>. Each of the contacts 28<SP>1</SP> ... 28<SP>n</SP> is controlled, via a described gas tube amplifier and relay, by one of the outputs from a multicathode counting tube 77, Fig. 6, the operation of which is described below. When such a contact is closed the circuit of the motor 24 is normally completed and the latter drives the disc 20 round until the associated pair of the contacts 25<SP>1</SP> ... 25n are opened by a cam notch 27a or 27b. This stops the motor and locates all the read/record heads 51 ... 5n in a position appropriate to the desired disc track. Selection of a particular disc surface is achieved by rocking the appropriate read/record head (say 5<SP>2</SP>, Fig. 4) into contact with the required surface by closing one of a series of contacts 122<SP>1</SP> ... 122n (say 122<SP>2</SP>) and so energizing an associated solenoid 32 which pulls its armature 34 into engagement with the end of the supporting arm 6<SP>2</SP>, pushing over the lever carrying the read/ record head by a pin 38. Besides rocking the head 5<SP>2</SP> into contact with the surface of the disc 3<SP>1</SP> contacts 45<SP>2</SP> are closed, and these connect up the head with input/output channels as described below in relation to Fig. 6. In that Figure the contacts 122<SP>1</SP> ... 122n are controlled by the output signals from a multicathode counting tube 78. Intermediate store. An intermediate store in the form of a magnetizable drum (Fig. 5, not shown) is employed in the course of transferring information from a magnetizable tape to a particular address in the disc store, or in the reverse direction. The drum is arranged to perform a complete revolution during the reading of one unit of information from the tape; the storage discs, however, rotate at a much lower speed since 100 units of information are stored in one track during each disc rotation. Data signals. Each unit of information consists of a number of groups of pulses. The first pulse in each group, e.g. 98, 102, Fig. 6a, is used for synchronizing purposes, while the remaining pulses represent a digit in each case. In Fig. 6a the first group 99 identifies the track on a storage disc, the second group 101 identifies a particular disc surface, and the third group 104, consisting of a two-digit number, identifies a particular section of the disc track. The remaining groups represent the information to be stored. Entry of data. The selection process is started by changing over a switch 81, Fig. 6, from a to b. This causes a charged capacitor 82 to discharge through a resistor 83, the voltage pulse so developed opening a gated amplifier 84 which passes a clock pulse picked up by a head 52 from the intermediate store 47. This pulse sets trigger circuits 85, 70 and 65, and renders conductive a gas tube 87 through which a capacitor 89 discharges, energizing a solenoid 90 to release a one-revolution clutch 93 whereby a roller 96 is rotated by a motor 94 to feed a length of tape 60 bearing a unit of information. The information pulses are read by a pick-up head 61 and pass via a gated amplifier 63 to be recorded on the intermediate drum store 47 by a head 56. The pulse developed across resistor 83 to open the gated amplifier 84 is arranged to last until a second clock pulse passes through 84 and again causes energization of the solenoid 90, permitting a second revolution of the feed roller 96. However, the change-over of the trigger circuit 65 by this second clock pulse now connects the pick-up head 61 through a gated amplifier 64, so that the second unit of information is recorded on another track of the drum 47 by a head 55. During this second phase a gated amplifier 66, selected by the trigger circuit 70 which is also subjected to the change-over clock pulses, passes the components of the first unit of information picked up by a head 54 to a gated amplifier 116. The first item in a unit of information comprises a synchronizing pulse followed by a number of pulses equivalent to the number of the track in which subsequent information is to be recorded. The synchronizing pulse passes through the amplifier 116 and sets a mono-stable flip-flop 118 which, in its stable (reset) state, blocks a gated amplifier 117. Thus subsequent pulses, besides maintaining the flip-flop 118 in its unstable state, pass through the gate 117 and a further gate 72 and step on a multicathode counting tube 77 to register the number of the track required. The final output signal from the counting tube 77 controls the positioning of the arm(s) carrying the disc read/ record heads as described above with reference to Figs. 1 and 3. When the mono-stable flip-flop 118 returns to its reset position a pulse is delivered via an amplifier 120 to a multicathode tube 71 which controls a series of gates 72 to 75 each leading to a counting tube. Thus, as the glow in tube 71 moves from cathode 71<SP>2</SP> to cathode 71<SP>3</SP>, the gate 72 is closed and a gate 73 is opened to pass the next group of pulses (after a synchronizing pulse), which represents the number of the disc on which the subsequent information is to be stored, for registration on the counting tube 78. The final registration of the tube 78 controls the energization of an associated solenoid, such as solenoid 32, Fig. 4, whereby the selected read/record head, e.g. 5<SP>2</SP>, is brought into operative relationship with the selected disc track as described above. When the mono-stable flip-flop 118 returns to its stable position a further pulse steps on the tube 71 and opens the gate 74 to allow registration on a tube 79 of the units digit of the number identifying the section of the track to be selected. The tens digit of this number is subsequently registered in a further counting tube 80. When entry of this two-digit number has been completed the glow in tube 71 is stepped on to the electrode 71<SP>6</SP> the output signal from which opens a gated amplifier 76 and restores the trigger circuit 85 thereby blocking the gate 116 and preventing the passage of further signals from the amplifier 66 to the counting tubes. The opening of amplifier 76 allows a synchronizing pulse, picked up from the disc 3<SP>1</SP> by a special head 15, to pass through and set a trigger circuit 123 which opens a gated amplifier 124 and allows a pulse picked up by a head 51 at each rotation of the intermediate store 47 to be fed into the units denomination of the multicathode counter 79, 80. When this counter has been completely filled by entering a number of pulses equal to the complement of the number entered during the previous phase, an output signal on line 80<SP>2</SP> operates a trigger 122 which opens a gate 69 to allow data pulses from the head 54 to pass through at the appropriate time so as to be located in the desired section of the selected track on one of the discs 3<SP>1</SP> ... 3<SP>5</SP>. Reading out information. The Specification also describes how the above procedure may be reversed so that information from an address on one of the discs 3<SP>1</SP> ... 3<SP>5</SP>, called up by the setting of an input device 133, may be read out, recorded on the intermediate store by one of the heads 53, 54 and finally read out by one of the heads 55, 56 to control the output of the information e.g. by printing means. In another embodiment (Fig. 25, not shown) the data pulses which follow the address signals in each unit of information are also entered on multicathode counting tubes, and when the final address is determined clock pulses are fed into these tubes and also recorded in the appropriate track of a disc until the carry pulse from each successive tube blocks further recording in that denomination. It is, therefore, complementary values which are stored rather than true numbers, but since a further complementation occurs during read-out the result is unaffected. Various suggested modifications include the provision of detachable surfaces for the discs (Fig. 15, not shown), the interleaving of adjacent stacks of discs for compactness (Fig. 18, not shown), close packing of discs with provision for separating adjacent discs as required to gain access for the read/record head to operate upon a particular surface (Fig. 21, not shown), and means for driving discs at their outer peripheries, and arrangements for recording in radial instead of circular tracks. Means for checking by employing check symbols or recording twice and comparing results, are also mentioned. The discs may have helical or concentric grooves therein and may move in a continuous or stepwise manner. Various codes may be employed to represent the information.. The intermediate store may consist of an array of static saturable magnetic cores or other bi-stable elements.