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Subtraction Apparatus

IP.com Disclosure Number: IPCOM000098862D
Original Publication Date: 1958-Aug-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Muenzer, BM: AUTHOR

Abstract

There is shown subtracting apparatus in which upon the application of a subtract operation initiating signal to the circuit various operations take place. Serial signals representative of succeeding orders of the decimal digits of a subtrahend are applied from a suitable source to the 10's complement conversion device. This device converts each serially received subtrahend digit to its 10's complement form and presents it in turn to a single order accumulator.

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Subtraction Apparatus

There is shown subtracting apparatus in which upon the application of a subtract operation initiating signal to the circuit various operations take place. Serial signals representative of succeeding orders of the decimal digits of a subtrahend are applied from a suitable source to the 10's complement conversion device. This device converts each serially received subtrahend digit to its 10's complement form and presents it in turn to a single order accumulator.

In timed serial relationship with the presentation of the 10's complement form subtrahend digits to the accumulator, corresponding orders of the minuend are routed from the storage register to the accumulator. In this device the two digits are added to generate, by addition, a difference digit. Each difference digit is transmitted in turn from the accumulator back to an appropriate order in the storage register. The accumulator is reset after each difference digit is transmitted.

The accumulator includes a 10's overflow sensing device that is normally set in a no 10's overflow indicative state. It is transferred to a 10's overflow state, if a 10's overflow occurs during an accumulator cycle. If the 10's overflow state results, it is indicative that the minuend

digit is at least as large as the subtrahend digit so that the subtraction is satisfied for the particular orders of the subtrahend and minuend just operated upon and operations for that order subtrahend and minuend digits are terminated. If the no 10's overflow state results, which is indicat...