Patent GB-684206-A (GB)
Title: Impulse-responsive electronic accumulators
IPC: H03K21/08
Filed: 1951-01-01
Abstract: 684,206. Digital electric calculating-apparatus. NATIONAL CASH REGISTER CO. Jan. 1, 1951 [Jan. 7, 1950], No. 32/51. Class 106 (i). Electronic counting - apparatus comprises series-connected trigger pairs and a feed-back path connecting a trigger pair later in the series over a resistor to the input circuit of a tube of a trigger pair earlier in the series so that a steady potential in accordance with the condition of operation of the trigger pair later in the series is applied to the earlier trigger pair. Each order of a decimal accumulator comprises four stable trigger circuits A, B, C and D, each including a double triode. Positive input pulses are applied to the left-hand grid of a double triode 220 to produce negative impulses at the connected anodes which are applied to the trigger A. The first seven pulses are counted in normal binary fashion so that after the seventh pulse, the triggers A, B and C are " on " (their left-hand sections conducting) and the trigger D is " off." The eighth pulse switches trigger A " off." The triggers B and C are consequently switched " off " and the trigger D is switched " on." The right-hand anode of this trigger is resistance-coupled over lead 294 to the left-hand grids of both triggers B and C so that when the trigger D is " on," a strong positive bias is applied to these grids. The triggers B and C are thus switched back " on " so that the eighth pulse results in the trigger A being " off " and the triggers B, C and D being " on." The ninth pulse merely switches the trigger A "on." The tenth pulse switches the trigger A " off " and the pulse applied to the trigger B temporarily overcomes the bias due to the feed-back connection from the trigger D and switches the trigger B " off." Similarly, the trigger C is temporarily switched "off" " and passes a pulse to the right-hand valve of the trigger D which is received at substantially the same instant as the left-hand valve receives a pulse from the trigger A over a connection from its right-hand anode and leads 306, 333. The trigger D is thus switched "off" " and the positive bias is removed from the left-hand grids of the triggers B and C which then assume steady " off conditions. In order to manifest the digit registered in the order at any instant, the anodes of the triggers A, B, C and D are connected over resistances to ten digit-representing leads 415. The arrangement is such that the lead corresponding with the digit registered is at a lower potential than any of the other leads. Transfer. When the trigger D is switched " off," which only occurs as the digit registered changes from 9 to 0, the drop in potential of the right-hand anode produces a pulse which is applied to the left-hand grid of a double triode 375 included in a trigger circuit. This trigger is thus switched to conduct in its right-hand section. After the completion of the digitentry, negative transfer-effecting pulses are applied over a lead 395 to the right-hand grid of this trigger which, if it has been switched, is thus restored. The consequent rise in the potential of the right-hand anode applies a positive pulse to the right-hand grid of the input double triode 220 for the next order over a lead 372 and a condenser (not shown). A negative pulse is thus applied to the trigger A of that order to enter one therein. Zeroizing. The opening of a switch 267 removes the negative bias from the right-hand grids of the triggers A, B, C and D and from the left-hand grid of the transfer-storage trigger 375 to cause the triggers to assume their normal states.