Patent GB-862122-A (GB)
Title: Method and means for the selection of stored digital data signals
IPC: G06K17/00
Filed: 1957-11-01
Abstract: 862,122. Magnetic record-card apparatus. DIRKS, G. Oct. 23, 1958 [Nov. 1, 1957], No. 34099/57. Class 106 (1). Data sheets 1 (Fig. 1) each having a magnetizable area (within the broken line 3) with a number of information tracks 4, 5, &c. thereon are withdrawn from a stack (Fig. 3) one at a time in the direction of arrow A, Fig. 1, by projections 90 on tapes 82, 83 engaging ears 2 on the sheets, and have a first (sheet) identification area 4A sensed at 65; if the output of 65 when compared with a desired sheet identification number indicates that the sheet is not the correct one it is returned to the stack after only a partial withdrawal by reversing motor 91 and the next sheet is examined in the same way. When the comparison indicates that the correct sheet has been withdrawn, its withdrawal is continued until the output of 65 when compared with a desired block identification number indicates that the desired block 4B, 4C, ... or 4Z has been reached, and the corresponding information track 7B, or 9C, is then read out at 64. As described, each sheet provides stock part numbers in each of the tracks 7B, 9C, ... for a different sub-assembly of a single machine, and the machine identification number is recorded in block 4A, and sub-assembly identification numbers in blocks 4B, 4C, ... of track 6. Track 4 contains block end marker signals, and tracks 5, 8B, 10C, ... clock signals. The stack of sheets (Fig. 3, which shows sheet-selecting apparatus similar to that described in Specification 818,235) is first brought to approximately the correct position for removal of the desired sheet by closing contacts 73 (as by a uni-selector) to unlatch arm 76 and allow threaded rods 70, 71 to rotate (through slipping clutch 74) and raise or lower the stack; arm 95 is then unlatched to similarly enable motor 91 to bring a sheet to sensing station 65, the heads 14-16 (Fig. 4) of which read tracks 4-6 of 4A. Clock pulses are generated corresponding to each possible sheet identification bit, and gate the latter to a comparison circuit 21 where the sheet identification number is compared bit-by-bit with the clockpulse-shifted contents of circulating shift register 22, which has previously been filled with the desired sheet identification number. A block end marker signal from head 14 then tests 21 for identity, and if this is signalled a thyratron 23 is fired to open gate 28 for similar comparison of track 6 (sub-assembly) identification numbers with a desired sub-assembly identification entered into shift-register 29, and energize relay 27 which itself energizes 97 to release arm 95 and allow the necessary further advance of the sheet. If the sheet is not the correct one, thyratron 24 is fired by the block end marker signal through delay 25 (23, if previously fired, prevents this) and a relay 26 reverses motor 91 by switch 68 to return the sheet to the stack and prepare for the withdrawal of the next sheet. When comparison circuit 30 signals that the correct subassembly block of the correct sheet has been reached, the block end marker signals, which have been counted on multi-cathode counter tube 33, are cut off by thyratron 31 at gate 32; the count is then used to switch in by relays 48 2 -48 9  read heads 34 appropriate to the correct sub-assembly block, which commence read-out of part-numbers appropriate to the sub-assembly from track 7B, or 9C, or ... when the simultaneous block and clock signals at the end of tracks 4 and 5 close switch 35a through gate 35. When reading is completed, a stud 81 on tape 82 closes switch 36 to operate reversing- switch 68, and opens 37A-37C to extinguish the thyratrons, return the count in 33 to zero, and prevent further read-out. Fig. 2 illustrates a modified form of magnetic sheet in which the information tracks are arranged at right-angles to, and in the same position relative to, the corresponding identification blocks; in this embodiment the output of comparison circuit 30 (Fig. 4) stops the sheet when the desired subassembly is identified, and a read-head is then caused to traverse the appropriate information track.