Patent GB-791243-A (GB)
Title: Self-complementing gas tube accumulator
IPC: G06F7/498
Filed: 1955-05-24
Abstract: 791,243. Electronic counting apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. May 24, 1955 [May 28, 1954], No. 14927/55. Class 106 (1). In an electronic accumulator using a multicathode tube of the kind described in Specification 735,750 as each denominational counter, Fig. 2, counting is effected in each denominational order by applying positive pulses to all the parallel-coupled digit cathodes, each positive pulse raising their potential from their normal negative potential (- 48 v) to a level above that of the transfer cathodes (55 v.) and below that of both the anode (400 v.), and the paralleled complement cathodes (125 v.) and causing the discharge to pass via a transfer electrode to the adjacent digit cathode. Complementation of a registered number is effected by interchanging the potentials of the transfer and complement cathodes and then applying a single positive pulse to the digit cathodes-the discharge then passing via a complement cathode to the digit cathode representing the complement of the registered number. Input to each denomination, for example the units, is via a gas-filled thyratron 60, Fig. 2, which receives, for addition, pulses A, Fig. 3, from a pulse generator 100, on its anode, and which is caused to fire by the sensing of a hole in a record card to pass pulses equal in number to the value of the hole sensed to the digit cathodes D0, D1-8, D9. Any carry which is detected by the rise in potential of the transfer cathode T9-0 between digit cathodes 9 and 0 as the discharge passes from digit cathode 9 to 0, is stored in a thyratron 80 until a carry-period, cycle point X, Fig. 3, during which period the screen grids of all the input thyratrons 60 are lowered in potential from 55 v. to - 100 v., by camcontrolled relays, but those input thyratrons (for example 60<SP>1</SP>) which follow denominations from which a carry has to be passed, have their screen grids held at a positive potential by the cathode follower action of the appropriate carry storage thyratron (e.g. 80) and the pulse A, Fig. 3, occurring in cycle point X passes through and effects carry. No special provisions exist for through carry. For subtraction, a pulse train S, Fig. 3, is applied to the input thyratrons. This pulse train contains two pulses more than in train A, one before cycle point 9 and one after cycle point X, these being effective to complement each tube both before and after the addition of the desired number of pulses, the potentials of the transfer and complement cathodes being interchanged at the appropriate times by cam-controlled contacts. Read-out is effected by applying ten pulses, train R, to each denomination and using the differentially timed energizations of the carry storage thyratrons to control printing magnets. The accumulator is particularly adapted for use where a sum of amounts each punched on a record card, which sum should be zero, is being evaluated, in that it overcomes the ambiguity that if subtraction is done in the usual manner such a result can be represented as a row of either nines or zeros. This ambiguity is removed by first subtracting unity from the accumulator, then entering the amounts to be totalled, and finally entering unity. The initial subtraction of unity is effected, for a two denominational accumulator as shown, by adding 99 which is punched on a first card. Then the amount cards are sensed, first by an upper row of brushes for sign indications, and then by a lower row for the numerical amount, and finally a control card is sensed which causes unity to be added (train C on anodes and a positive pulse on units input thyratron control grid), which, if the sum " checks " causes the accumulator to reburn to zero and supply a pulse, via the carry thyratron of the tens counter, to a check control unit. Specifications 639,827, [Group XL (a)], 691,901 and 692,415 also are referred to.