Journal of Software Engineering and Applications, 2014, 7, 513-529 Published Online May 2014 in SciRes. http://www.scirp.org/journal/jsea http://dx.doi.org/10.4236/jsea.2014.76048 A Code Correlation Comparison of the DOS and CP/M Operating Systems Robert Zeidman Zeidman Consulting, Cupertino, USA Email:
[email protected] Received 3 April 2014; revised 1 May 2014; accepted 8 May 2014 Copyright © 2014 by author and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract For years, rumors have circulated that the code for the original DOS operating system created by Microsoft for the IBM personal computer is actually copied from the CP/M operating system de- veloped by Digital Research Incorporated. In this paper, scientifically tested and accepted forensic analysis mathematical techniques, step-by-step processes, and advanced software code compari- son tools are used to compare early versions of the two code bases. The conclusion is reached that no copying of code takes place1. Keywords DOS, CP/M, Copyright Infringement, Software Forensics, Software Correlation 1. Introduction For purposes of better understanding, the introduction includes the historical background and the legal issues. 1.1. Historical Background Gary Kildall is the man who, according to some, could have been and should have been the reigning king of software. Kildall created the CP/M (Control Program for Microcomputers) operating system that was used on many of the hobbyist personal computers before Apple and IBM introduced their machines. Kildall created 1Full disclosure: The process used is the process developed at my consulting company Zeidman Consulting.