GB973208A - Improvements in or relating to information storage devices - Google Patents

Abstract

973,208. Counters; electric selective signalling. DE HAVILLAND AIRCRAFT CO. Ltd. Nov.17, 1960 [Sept. 22, 1959], No. 32288/59. Headings G4A and G4H. The elements of a ring counter are associated with elements in a second ring which can be made to complete a cycle, so indicating the state of the first ring. The first ring comprises magnetic core 10-13 each with input winding 14, 15 and output windings 16, 17. According to whether the counter is to shift left or right so line 22 or 24 is earthed. Input impulses are applied alternately to leads 18, 19. Suppose that the counter is set to shift right and that element 11 in the first ring and the associated element 31 in the second ring are set to 1. Then an impulse on lead 19 turns 11 to 0 inducing an impulse in winding 17 which is amplified by the associated transistor 21 to energize winding 15 of element 12 which therefore turns to 1. The pulse through winding 14 also passes through winding 34 of element 31 so that the second ring also advances in like manner. The pulse also turns a bi-stable element 27 associated with element 12 to "on". The elements 27 are so arranged that the current flow through resistor 28 is proportional to the value of the digit represented. In reverse counting transistors 20 are effective instead of transistors 21. In read-out line 41 is earthed to render transistors 40 responsive to pulses from output windings 38. The second ring is driven through a complete cycle by an appropriate number of pulses on line 44, the time taken for the "1" condition to reach the end of the ring indicating the condition of the first ring. Measuring voltage. The voltage to be measured is applied at 50 to a null detector 51 together with the voltage applied across resistor 28. According to whether the voltage across 28 is greater or less than the test voltage so a tristable circuit 52 marks line 59 or 57 to cause left or right shift of units counter B. The units counter can transfer positively or negatively to tens counter A through gate 66 or 67, one or other of which is disabled by line 57 or 59. When equality between 28 and 50 is established line 58 is marked to inhibit gate 63, so stopping stepping of the counters. Read-out is effected from the C registers. If the test voltage is outside the limits of the measuring device, when counters A and B together reach their upper or lower limits they energize gate 68 or 69 to stop further operation. Specification 973,207 is referred to.