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Divide-By-Five Algorithm and Circuit

IP.com Disclosure Number: IPCOM000060336D
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08

Publishing Venue

IBM

Related People

Authors:
Dyche, MP Savage, CP [+details]

Abstract

Division of a binary number by five is often required in display applications in which 80 characters per row are displayed, because 5 is a factor of 80. This may be achieved in either hardware or software by, instead of dividing by 5, multiplying by 0.2. The binary equivalent of 0.2 is the recurring number 0.00110011 ..... A simple sequence of shifts and addition of each input bit to the next highest order bit effects multiplication by 0011. Further stages carrying out the same sequence can be added until the result is of sufficient accuracy. A hardware embodiment for binary numbers < 127 is shown in Fig. 1. The input is applied on lines 10 to single-bit adders 12 in which each input is added to the next highest-order bit, thus effectively multiplying it by binary 11.