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Bi-Directional BCD Counter

IP.com Disclosure Number: IPCOM000097764D
Original Publication Date: 1961-Jun-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Heilweil, MF: AUTHOR

Abstract

The circuitry is a single decade of a bi-directional binary coded decimal counter. Each decade represents the digits 1, 2, 3 and 4. A counter of any size is built by connecting decades in series. There are two inputs to the counter, these being the counting input X, the direction input U and its complement bar U. Every rise and fall of the counting input causes the count to change by one. The direction of the change is determined by the direction input signal. The direction signal is changed only when the counting input signal is down. Thus, a direction signal change has no effect upon the value in the counter.

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Bi-Directional BCD Counter

The circuitry is a single decade of a bi-directional binary coded decimal counter. Each decade represents the digits 1, 2, 3 and 4. A counter of any size is built by connecting decades in series. There are two inputs to the counter, these being the counting input X, the direction input U and its complement bar U. Every rise and fall of the counting input causes the count to change by one. The direction of the change is determined by the direction input signal. The direction signal is changed only when the counting input signal is down. Thus, a direction signal change has no effect upon the value in the counter.

The counter utilizes NOR logic (AND-INVERT) exclusively. Each decade consists of four D.C. binary triggers plus interconnecting logic. The trigger is described in the April 1960 IBM Technical Disclosure Bulletin, Volume 2, Number 6, page 100. Triggers T1, T2, T3 and T4 represent the values 1, 2, 4 and 8, respectively. For example, if triggers T1 and T3 are on and triggers T2 and T4 are off, the count is 5. The interconnecting logic may be considered in two parts, the upper part for counting up and the lower part for counting down.

An output Z is provided for driving the next higher order decade. For every ten input signals, there is one output signal on this line. The trigger outputs are used directly to indicate the value of the counter. The set and reset inputs of the trigger are used to reset or set the counter to any value. T...