Patent GB-1220616-A (GB)
Title: Information storage and processing
Inventor: BOBECK ANDREW HENRY
IPC: G11C11/14
Filed: 1968-04-18
Abstract: 1,220,616. Magnetic storage apparatus. WESTERN ELECTRIC CO. 18 April, 1968 [2 Aug., 1967], No. 18295/68. Heading H3B. [Also in Division G4] In magnetic information storage apparatus comprising a sheet of magnetic material logic operations are performed between single wall domains of an information representative pattern of presences or absences of such domains. The invention is applied to a content addressable memory 10, Fig. 1, comprising a sheet 11 of magnetic material having a preferred direction of magnetization normal to the plane of the sheet and including first, PY1 . . . PYn and second PX1-PXm sets of orthogonal propagation conductors connected to drivers 12, 13 respectively. Information is stored in the sheet 11 as the presence and absence of single wall domains in selected positions or blocks so organized and spaced apart as to enable various logic operations. The drive conductors may be arranged in orthogonal slots formed in a high permeability base-plate and a sheet of ferrite positioned over the posts. The propagating conductors are in the form of interconnected conducting loops arranged for three phase operation, Fig. 2. Each representative conductor H, V includes three distinct sets of interconnected conducting loops P1, P2, P3 of which the P1 set couples the first, fourth . . . , blocks, the P2 set couples the second, fifth . . . , blocks, and the P3 set couples the third, sixth . . . , blocks. Each set of eighteen blocks defines a bit location in which the presence and absence of a domain represents a binary value, the binary "1" and "0" positions being shown by the encircled plus signs. The domains are moved selectively by pulses on the propagation conductors generating a positive field. In operation of the addressable memory the blocks defining bit locations are arranged in sets of three columns I, II, III, column I being used only for permanent storage and column II for logic operations. Fig. 23 shows a portion of sheet 11 in which two binary words are arranged with their bit locations in columns, the first three bits forming the match tags 001 and 100 respectively. Replicate operation.-The first logic operation is to replicate all stored words so that column II is provided with bit representations corresponding to column I. This is achieved by first applying a pulse to conductor V3P2 to move the presence and absence of domains of column I one block to the right and then applying a pulse to each conductor V2P2 and V4P2 to split the binary representation. Finally a pulse is applied to conductor V5P2 to move the newly generated indications to the centre column of blocks of column II. Move to logic portion.-The duplicate of the representative match tags is moved to a different logic portion of sheet II by pulsing conductors V5P1, V5P3, V5P2, V5P1 using column II as a shift register Fig. 25 (not shown). Invert operation.-All the bits in match tag positions corresponding to the relative positions of zeroes in an assumed input tag are then inverted, assuming an input tag 001. In a first step the binary representation in each of the first two bit locations of the match tag of every stored word in the logic portion are moved from column II to column III, Fig. 26 (not shown), by pulsing conductor H2P3 and then conductor H5P3 and then sequentially (or concurrently) conductors H2P1, H5P1 and H2P2 and H5P2. The actual invert operation is then performed only on information in columnIII and exchanges the positions of domains and absence of domains in the one and zero representations in each bit location one for the other by pulsing H2P3, H5P1, V9P3, V7P1, V9P1, V7P3, V9P2, V7P2, H2P2 and H5P2. The information is then moved back into columns II by pulses on conductors H2P1, H5P1, H2P3, H5P3, H2P2 and H5P2. Type A to type B conversion.-The information in the form shown in Fig. 2 is next changed to that shown in Fig. 3, type B by a simple rotation of the indication in one cell about that in the other by applying consecutive pulses to conductors H2P3, H2P1, H2P2, V8P3, V8P1 and V8P2, Fig. 28. Consecutive MINOR AND operations.-First the indications in the third from the top binary representations in each match tag are moved upward to blocks H3P2 spaced one intermediate position apart from the corresponding indications in the second binary representation, conductors H6P2, H1P2, H2P2 and H3P2 are pulsed. A pulse is then applied to conductor H4P2 corresponding to the intermediate position. In word one Fig. 31 the third binary representation moves into the intermediate position to the exclusion of the second binary domain whereas in word two no domain is excluded and a domain from each representation moves to the intermediate position. A pulse of appropriate polarity to collapse a domain is then applied to conductor H4P2 so as to annihilate the domains and then a pulse is applied to H4P2 moving any remaining domains into block H4P2. For word one a domain remains whereas for word two none remains. The above process is repeated between the indications in the first binary representation of each stored match tag and the corresponding result of the MINOR AND operation. Only if a stored match tag matches the input tag will a domain appear in column II, Fig. 35 (not shown). Eliminating mismatched words.-A domain in column II is replicated five times to fill all cells in the bit locations of the sorted match tag and moved downwards by appropriate pulsing of the conductors. Next the match information in column II is propagated in parallel to column III. Each word in the memory is again replicated as described above and the words replicated in column II are moved again to the logic position so as to be adjacent to the column of domains or no domains in column III. A MINOR AND operation is carried out between columns II and III. Only matched words appear in the logic portion after this operation and mismatched words are eliminated. The information associated with a matched tag may then be updated by moving information along columns of bit locations in the logic portion of sheet 11 to positions corresponding to that portion of the match words to be changed. Alternatively the match words may be considered stored in parallel in shift register channels for propagation to output positions for detection by circuit 18. The control circuit 16 may be a portion of sheet 11 or a separate sheet in which a plurality of shift register channels are defined, Fig. 42 (not shown).