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Reversible Counter

IP.com Disclosure Number: IPCOM000098182D
Original Publication Date: 1960-Apr-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 67K

Publishing Venue

IBM

Related People

Stevenson, DA: AUTHOR

Abstract

This accumulator circuit makes it possible to use decade gas counter tubes for counting down, as well as for counting up.

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Reversible Counter

This accumulator circuit makes it possible to use decade gas counter tubes for counting down, as well as for counting up.

During reading each pulse applied to input A steps the lowest order tube one place, in the direction determined by the polarity of input C. One polarity of C enables the count up drivers +DR through the cathode follower CF2. The opposite polarity enables the count down drivers -DR through the inverter I and cathode follower CF1 combination.

A carry is propagated between tubes when there is a 9 to 0 transition if counting up or when there is a 0 to 9 transition, if counting down. A 0 to 9 transition in the highest order indicates that the input A pulses have driven the total count negative. Negative total counts are in complement form. Trigger TM which is initially + is set - by a 0 to 9 transition, and to + by a 9 to 0 transition. The minus relays RM are picked when the trigger TM is set to -.

The number stored is read out by setting the trigger TO to pick the readout relays RO and pulsing input B ten times, driving each tube one full revolution up, if the total count stored is positive; or, down if the total count stored is in complement form. Each of the B pulses also steps the ten position rings, one position in the opposite direction. A transition from 9 to 0 when a positive total count is stored (or, 0 to 9 when a complement is stored), from any tube, stops the corresponding ring. After ten B pulses, all the rings will...