985, 347. Permanent data stores. INTERNATIONAL BUSINESS MACHINES CORPORATION. Aug. 28, 1963 [Dec. 10, 1962], No. 46522/62. Heading G4A. [Also in Divisions H1 and H2] A permanent data store comprises a plurality of elongated insulating carriers each having a plurality of apertures spaced along its length in at least one row, the carriers being stacked with corresponding apertures in registration; a plurality of transformer cores passing through the registering apertures, each core having an associated sensing winding; and drive conductors for each row extending continuously along the length of each carrier and passing to one side or the other of each aperture so as to thread or not to thread the associated transformer core, in accordance with the data stored. The permanent store described comprises a stack of 128 flexible tapes 15, Fig. 6, made of in-. sulating material and having two rows 16, 17 of sixty apertures, rectangular transformer cores each comprising a U-shaped part 13 and a straight I-shaped part 14 passing through each pair of corresponding apertures. With each row of apertures is associated on each tape a corresponding drive winding 18 or 21, formed by deposition on the tape and threading or not threading the transformer cores according as a binary "1" or "0" is stored, each row being regarded as storing a 60- bit binary data "word" which may be read out by applying a pulse to the required winding 18 or 21 to produce output signals on the transformer secondaries 19 only where a "1" is stored. Tape fabrication. Each tape after punching with the transformer core apertures 16, 17 has deposited thereon conductive ladder networks 24, 25, Fig. 7, the unwanted portions of the networks 24, 25 being removed by punching (Fig. 8 no shown), etching or abrading (Fig. 9 not shown). As shown in Fig. 41, a copper clad polyester tape 135 is cleaned at 137, a layer of photo-resist material being applied which is then dried and an exposure made of the required continuous ladder networks. The tape is then passed through an etching bath 140, the unwanted photo-resist material being removed at 141. The required data may be punched on the tape from a program stored on punched cards (Fig. 42, not shown). Tape arrangements. In practice, each tape is punched with four rows of thirty apertures each, Fig. 10, the two outer rows being connected by a conductor 51 to form a first 60-bit stored word and the two inner rows being connected at 52 to form a second 60-bit word, the four input/output connections thus being available at one end of the tape on an extension 53. The stack of 128 tapes is arranged in two halves of 64 tapes, the two halves being in inverted relationship, Fig. 14 with an additional insulating tape (not shown) separating the two halves. Reducing inter-tape coupling. Due to the proximity of the tapes to one another undesired inter-tape capacitative and inductive coupling may result in damped oscillations or ringing in the selected winding. This effect may be reduced in three ways. Firstly, each transformer core may carry a short-circuit winding in the form of a damping resistor, these resistors being formed as loops 78, Fig. 22, on an additional insulating tape 76, one or more of such tapes being arranged in the tape store stack. Secondly, with each transformer core S, Fig. 23, may be associated an additional core T, the drive winding being wound similarly through the associated cores S, T, the core T being made of a lossy material or having resistive loops as described above. Thirdly, there may be three types of storage tapes (Figs. 24 to 26, not shown), used in turn in the tape stack and having their core apertures displaced by different amounts with respect to the centres of the ladder network elements so that when the tapes are positioned with the apertures aligned, the conductive drive windings in adjacent tapes are relatively displaced. Tape module construction. The tape stack of 128 tapes is mounted in an assembly comprising end blocks 82, 83, Fig. 27 spaced apart by rods 84. Into the blocks 82, 83 are screwed aligning pins 86 on which the tapes 39 are mounted and on the rods 84 are mounted the transformer core carrier assemblies 88, shown in detail in Fig. 31. Each core carrier assembly 88 comprises slots 92 for the I-shaped parts 14 of two cores, the four ends of two U-shaped parts 13 passing through holes in the assembly 88 to contact the I-shaped parts which are retained in position by leaf springs 96 cooperating with a retainer 94 which slides into retaining position and has contact pins 97 for making connections to the transformer secondaries which are wound in grooves 98 on the assembly 88 and not on the I-shaped parts themselves. An insulating sheet 98 Fig. 27, is placed over the closed ends of the U-shaped parts and is retained in position by brackets 99, 100, 101. The tape extension leads 53 are fanned out and plugged into one of two module boards 105, where the plugs on the tape connected to the word drive windings can be soldered in position in holes in the boards. Each board 105, Fig. 33 has a first group of four 32-hole columns 107, 108, 109, 111 and a second such group 112, 113, 114, 115, there being a central column 116 of 32 holes. The first two holes in the column 116 are connected respectively by leads 117, 118 to all the holes in the respective columns 109, 111, the last two holes being similarly connected to the columns 114, 115 and the remaining holes in the column 116 are connected each to the corresponding holes in the columns 107, 108, 112, 113 via diodes 121, the connections being illustrated in Fig. 34 (not shown). Thus selection of one of the 32 intermediate holes in the column 116 together with selection of one of the four end holes will select a particular word drive winding on a particular tape. The holes 2 in the column 116 co-operate with plugs on a connector cable (Fig. 35, not shown) for addressing the store. A total of sixteen modules may be arranged to form a large capacity permanent store (Fig. 36, not shown), the selection circuits comprising transistors (Figs. 37-40, not shown).