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Even Odd Circuit

IP.com Disclosure Number: IPCOM000095982D
Original Publication Date: 1964-Nov-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Hack, GE: AUTHOR

Abstract

This circuit indicates when an even or odd number of binary one bits is present in a group of binary bits of a binary data processing system. The circuit is for providing a parity check based on an input which includes an even number of data bits plus a parity bit, thus making an odd number of inputs to the circuit.

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Even Odd Circuit

This circuit indicates when an even or odd number of binary one bits is present in a group of binary bits of a binary data processing system. The circuit is for providing a parity check based on an input which includes an even number of data bits plus a parity bit, thus making an odd number of inputs to the circuit.

The circuit has a plurality of pairs of transistors 1...8. The base or input electrode 9 of each transistor in the pair is also connected to the emitter electrode 10 of the other. The collectors 11 of the two transistors have a common path through resistor 12 to a positive voltage source. If the input to the base of both transistors is at a down level, approximately 0. 85 volts, or if the input to both transistors is at an up level, approximately 3. 0 volts, neither transistor conducts. If the input to one transistor is up and the other input down, the transistor which has the input at an up level conducts and saturates and changes the voltage level at the collector to a down level.

The pairs of transistors 1... 7 produce an up or down level at point 13 in accordance with the odd or even number of up levels at the inputs A... H. The comparison of the voltage level at point 13 with a voltage level resulting from the ninth or odd number input J is made by transistor pair 8. Instead of providing a pair of transistors to accommodate the ninth input, only a single transistor 14 receives the ninth input. Diodes 15 and 16 and resistor 17 at...