GB759547A - Improvements in electronic counters and accumulators - Google Patents

Abstract

759,547. Electronic counting-apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. April 13, 1954 [April 16, 1953], No. 10828/54. Class 106 (1). An electronic counter comprising a plurality of cascadecoupled bi-stable triggers (each containing two triodes) is characterized in that it also comprises electronic means for generating a first impulse, network means responsive thereto to produce a second impulse, means for transmitting said first impulse to change the stages of certain of the triggers and means for transmitting said second impulse to change the states of the other triggers for manifesting the complement of a number registered on the counter. Each denomination of a decimal accumulator, only the first and last of which are shown, comprises a counter consisting of four bi-stable triggers, 1-4, which when " on " (left-hand side conducting) represent the values " 1 ", " 2 ", " 2 ", " 4 ", repectively, and includes a rectifier in stage 2, which, when trigger 2 is " off " (righthand side conducting) permits a negative pulse from trigger 1 to pass direct to trigger 3, via line 32 and a feed-back connection, line 50, from stage 4 to stage 2. In each counter the nines complement of a registered number is obtained by changing the state of every trigger, and this is done by causing a thyratron 5 to fire and to lower the voltage on each anode, but because of the unsymmetrical connections to trigger 2 there is a risk of inter-stage pulses nullifying the effect of a lowering of the anode voltage. This risk is prevented by tapping the anode load of the thyratron 5 at two points 7, 8 so that when thyratron 5 fires negative-going pulses are transmitted along lines 13 and 34, that along line 34 to trigger 2, being the sharper, i.e. the voltage at terminal 49 rises more quickly to its former level than do the voltages at terminals 19 &c. Thus for example, suppose trigger 1 is " off (righthand side conducting) trigger 2 is " off ", and trigger 4 is " on ", then if similar negative pulses were applied to each trigger (i.e. if terminal 49 were connected to line 13, not as shown) as the voltages on the coupled anodes began to rise there would be, simultaneously, a positive pulse applied at grid 57, from trigger 1 via lead 32, and a negative pulse applied at grid 55, from trigger 4 via lead 50, and these pulses together might be strong enough to prevent trigger 2 changing its state, whereas, when a sharper pulse is applied to trigger 2 (i.e. when terminal 49 is connected as shown) the inter-stage pulses from triggers 1 and 4 find, when they arrive at trigger 2, that it - has flipped over to the " on state, and is actually in a state where grid 57 is more negative than cut-off and grid 55 is slightly positive (this is due to the " momentum " acquired by trigger 2 in flipping over). During the inversion operation a tube 80 is rendered conductive to block accumulator interdenominational carry.