A Code Correlation Comparison of the DOS and CP/M Operating Systems
Robert Zeidman
Zeidman Consulting, Cupertino, USA.
DOI: 10.4236/jsea.2014.76048   PDF    HTML     7,865 Downloads   11,625 Views   Citations


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 developed by Digital Research Incorporated. In this paper, scientifically tested and accepted forensic analysis mathematical techniques, step-by-step processes, and advanced software code comparison tools are used to compare early versions of the two code bases. The conclusion is reached that no copying of code takes place1.

Share and Cite:

Zeidman, R. (2014) A Code Correlation Comparison of the DOS and CP/M Operating Systems. Journal of Software Engineering and Applications, 7, 513-529. doi: 10.4236/jsea.2014.76048.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] Hamm, S. and Greene, J. (2004) The Man Who Could Have Been Bill Gates. Business Week. http://www.businessweek.com/magazine/content/04_43/b3905109_mz063.htm
[2] Computer History Museum (2013) What Was the First PC?
[3] Wallace, J. and Erickson, J. (1992) Hard Drive. John Wiley & Sons, Hoboken.
[4] Bellins, M. (2011) Putting Microsoft on the Map: History of the MS-DOS Operating Systems, IBM & Microsoft. About.com Guide. http://inventors.about.com/od/computersoftware/a/Putting-Microsoft-On-The-Map.htm
[5] Akass, C. (2006) The Man Who Gave Bill Gates the World. Computeractive.
[6] Smith, T. (2011) Microsoft’s MS-DOS Is 30 Today. The Register.
[7] Honan, M. (2011) Bill Gates Spent the Best Money of His Life 30 Years Ago Today. Gizmodo.
http://gizmodo.com/5825184/bill-gates-spent-the-best-money-of-his-life-30-years-ago-today,July 27,2011
[8] Conner, D. (1998) Father of DOS Still Having Fun at Microsoft. MicroNews.
[9] CP/M (2011) The First PC Operating System. http://www.digitalresearch.biz/CPM.HTM
[10] World Intellectual Property Organization (WIPO) (2010) Intellectual Property—Some Basic Definitions. http://www.wipo.int/about-ip/en/studies/publications/ip_definitions.htm
[11] US Copyright Office, Library of Congress (2008) Circular 1, Copyright Basics.
[12] (1970) The Law Professor Behind: ASH, SOUP, PUMP and CRASH. New York Times.
[13] Hollaar, L. (2009) Legal Protection of Digital Information, BNA Books. http://digital-law-online.info
[14] Melling, L. and Zeidman, B. (2012) Comparing Android Applications to Find Copying. Journal of Digital Forensics, Security and Law, 7, 55.
[15] Zeidman, R. (2009) DUPE: The Depository of Universal Plagiarism Examples. 5th International Conference on IT Security Incident Management & IT Forensics, 15-17 September 2009.
http://www1.gi-ev.de/fachbereiche/sicherheit/fg/sidar/imf/imf2009/slides/19-RumpSession1-Zeidman _DUPE_IMF2009.pdf
[16] Zeidman, R. (2008) Multidimensional Correlation of Software Source Code. The 3rd International Workshop on Systematic Approaches to Digital Forensic Engineering, Oakland, 22 May 2008, 144-156. http://dx.doi.org/10.1109/SADFE.2008.9
[17] Zeidman, R. (2007) Iterative Filtering of Retrieved Information to Increase Relevance. Journal of Systemics, Cybernetics and Informatics, 5, 91-96.
[18] Zeidman, B. (2006) Software Source Code Correlation. 5th IEEE/ACIS International Conference on Computer and Information Science, 10-12 July 2006, Honolulu, 383-392.
[19] Clough, P. (2000) Plagiarism in Natural and Programming Languages: An Overview of Current Tools and Technologies. Research Memoranda, CS-00-05, Department of Computer Science, University of Sheffield, Sheffield.
[20] Parker, A. and Hamblen, J. (1989) Computer Algorithms for Plagiarism Detection. IEEE Transactions on Education, 32, 94-99. http://dx.doi.org/10.1109/13.28038
[21] Whale, G. (1990) Identification of Program Similarity in Large Populations. The Computer Journal, 33, 140-146. http://dx.doi.org/10.1093/comjnl/33.2.140
[22] Wise, M.J. (1996) YAP3: Improved Detection of Similarities in Computer Program and Other Texts. SIGCSE ’96, Philadelphia, 15-17 February 1996, 130-134.
[23] Heckel, P. (1978) A Technique for Isolating Differences Between Files. Communications of the ACM, 21, 264-268.
[24] Wise, M.J. (1993) String Similarity via Greedy String Tiling and Running Karp-Rabin Matching. Department of Computer Science Technical Report, Sydney University, Sydney.
[25] Prechelt, L., Malpohl, G. and Philippsen, M. (2002) Finding Plagiarisms among a Set of Programs with JPlag. Journal of Universal Computer Science, 8, 1016-1038.
[26] Schleimer, S., Wilkerson, D. and Aiken, A. (2003) Winnowing: Local Algorithms for Document Fingerprinting. SIGMOD 2003, San Diego, 9-12 June 2003, 76-85.
[27] Zeidman, B. (2011) The Software IP Detective’s Handbook. 1st Edition, Prentice Hall, Upper Saddle River.
[28] Chaudry, G. (2011) The Unofficial CP/M Web Site. http://www.cpm.z80.de
[29] Harte, H.M. (2008) Howard’s Seattle Computer Products SCP 86-DOS Resource Website.
[30] (2011) CUSTOMIZING MS-DOS Version 1.23 and Later.
[31] Johnson, H. (2013) Tarbell S-100 Boards and Docs.
[32] Harte, H. (2005) Tarbell Electronics, Tarbell Electronics Manuals.
[33] Shvets, G. (2011) Intel 8086 Microprocessor Architecture. CPU World.
[34] Pournelle, J. (2011) Interview Discussing Kildall Secret Command in DOS.
[35] Evans, H., Buckland, G. and Lefer, D. (2004) They Made America. Little, Brown and Co., New York.
[36] Rivlin, G. (1999) The Plot to Get Bill Gates. 1st Edition, Crown Business, Random House, New York.
[37] (2011) Digital Research Family Members. http://www.digitalresearch.biz
[38] Young, J. and Kildall, G. (1997) The DOS that Wasn’t. Forbes.com, 7 July 1997.
[39] Digital Research, Inc. (1976) An Introduction to CP/M Features and Facilities.
[40] Ritchie, D.M. (1979) The Evolution of the Unix Time-Sharing System. Language Design and Programming Methodology, Sydney, September 1979.
[41] VargaekosEndre (2011) VAX: Virtual Address Extension. http://hampage.hu/vax/e_main.html
[42] Zeidman, B. (2012) Did Bill Gates Steal the Heart of DOS? IEEE Spectrum.
[43] (2012) Software Engineering Terminology, Software Engineering Lab (SGL) of the Institute of Computer Science Faculty of the University of Mons. http://informatique.umons.ac.be/genlog/SE/SE-contents.html
[44] Sega Enterprises Ltd. v. Accolade, Inc., 977 F.2d 1510 (9th Cir. 1993)
[45] Oracle America, Inc. v. Google Inc., No. C 10-03561 WHA (N.D. Calif. April 10, 2012)
[46] Gobry, P.E. (2011) 10 Behind-the-Scenes Crankers Who Built The World's Greatest Startups. Business Insider, 6 April 2011.
[47] (2011) IBM DOS 1.10 Ripped and Packaged by Tech Knight for the Endangered Software Archive. http://www.mirrors.org/archived_software/www.techknight.com/esa/download
[48] Sedory, D.B. (2008) Tutorial on Extracting “Disk Images” from a *.DIM File Using HxD (a Disk/Hex Editor). http://thestarman.pcministry.com/tool/hxd/dimtut.htm
[49] (2007) Defamation Definition. Free Online Dictionary.
[50] Paterson v. Little, Brown & Co., 502 F. Supp. 2d 1124, 1128 (W.D. Wash. 2007)

Copyright © 2023 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.