Browse Prior Art Database

One's Complement ALU Without End Around Carry

IP.com Disclosure Number: IPCOM000077745D
Original Publication Date: 1972-Sep-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Kazantizis, GB: AUTHOR [+2]

Abstract

In small data processing systems using one's complement arithmetic, oscillation or sustained ripples can occur in the arithmetic logic unit under certain conditions while performing addition or subtraction, causing erroneous results. One's complement arithmetic requires an end-around carry to function correctly.

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One's Complement ALU Without End Around Carry

In small data processing systems using one's complement arithmetic, oscillation or sustained ripples can occur in the arithmetic logic unit under certain conditions while performing addition or subtraction, causing erroneous results. One's complement arithmetic requires an end-around carry to function correctly.

The circuit shown minimizes oscillations or sustained ripples which could result from end-around carry operation.

Input busses A and B are connected in parallel to main adder 10 and auxiliary adder 12. The carry out is generated in auxiliary adder 12 during addition or subtraction operations. The carry out is connected to the carry in of main adder 10 by line 11. When the addition or subtraction operation is completed, the result appears on output line 13 from main adder 10.

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