Patent GB-1434857-A (GB)
Title: Logic device
IPC: H03K19/168
Filed: 1974-03-11
Abstract: 1434857 Magnetic storage arrangements INTERNATIONAL BUSINESS MACHINES CORP 11 March 1974 [16 April 1973] 10703/74 Heading H3B [Also in Division G4] Any desired logical function is performed on a binary word input from a data source by counting the "ones" content of the word, and comparing an output corresponding to the count with. a pattern of serial control bits selected according to the logical function required. Two embodiments are disclosed, both of which utilize the propagation of bubble domains in a magnetic sheet (not shown) by the combination of an overlay pattern of magnetically soft T and I bars and an in-plane rotating magnetic field. In one embodiment, Fig. 3, the position of a propagated single bubble representative of the count, is compared with that of the propagated serial control bits and provides an output if a single "one" positional coincidence is obtained. In the other embodiment, Fig. 12, a bridge circuit of bubble detectors is balanced and provides an output when the total number of- "ones" in the binary word and the control bit series is the same. Fig. 3. Bubble domains are introduced into the magnetic sheet (not shown) from a data source 48, and also from continuous bubble generators G1, G2, G3 whenever a respective write control 52, 72, 80 removes a bubble collapsing current from an associated conductor loop 54, 74, 82. The T and I bar overlay pattern provides operational regions 28, 30, 32, 34. In region 28 the "zeros" in a binary word introduced serially from the data source 48 are removed and the "ones" grouped together by causing each bubble, which represents a "one", to pause at an idler position 38-1 to 38-4 until moved one position to the right by the immediate proximity of the next propagated bubble. The data from 48 is followed by an uninterrupted stream of bubbles from generator G2 which cause the leading "one" bubble to advance through idler position 38-4 into region 30, the remaining bubbles passing to an annihilator 70. Region.30 normally contains a single bubble introduced by generator G2 and held at idler position 62-2. When the leading "one" bubble from region 28 passes into idler position 62-1 in region 30 the single bubble is displaced to the right and commences propagation into region 34; its time position being determined by the number of "ones" accumulated in the idlers of region 28. Region 32 provides a propagation path for the serial control bit bubbles which are introduced by generator G3 and collapsed by a current source and conductor loop 90, 92. In region 34 the propagation paths for the single bubble from region 30 and the serial control bit bubbles are adjacent, and if the single bubble and any one of the control bit bubbles positionally coincide, the single bubble is deflected towards an output 102, but not otherwise. In a modification, Fig. 10 (not shown), the input from the data source is entered in parallel. Fig. 12. In this embodiment magnetic bubble domains representing the binary word input X 1 -X 4  are positioned adjacent magnetoresistive detectors S1-S4 serially forming one arm of a bridge circuit energized from a source 132. The bridge is completed by resistors R A , R B , and a corresponding number of magnetoresistive detectors S<SP>1</SP> 1 -S<SP>1</SP> 4  adjacent a propagation path for bubble domains representing the pattern of control bits. Three such patterns a 1 , a 2 , a 3  are shown for sequential positioning adjacent the detectors S<SP>1</SP> 1 -S<SP>1</SP> 4 . If the number of "ones" in a compared word and a control bit pattern are the same, the currents through the two detector branches are equal and a matching condition is indicated by a null detector 130.