shown by computer manufacturers in spawning the vast numbers of computer systems that provide our field of study. Within this general acknowledgment, we would like to extend a very specific one to all the people in these organizations who helped make information available to us-the manuals, photographs, dates, etc., that this book has demanded in such great quantity.
We are indebted to the students who have read and criticized the various PMS and ISP figures: Richard Dove, Wayne Kohl, Michael Knudsen, Paul Mobus, and Charles Pfferkorn. Ken Fitzgerald and Anita Jones of IBM were kind enough to read the introduction to the IBM System/360.
Professor David L. Parnas initially reviewed the text and contents, thus providing many helpful suggestions. Our other colleagues, especially Professors Angel Jordan, Alan Perils, Herbert Simon and Everard M. Williams deserve a special thanks for their patience and encouragement.
Finally, we would like to thank those who were a part of the machine that assembled the book: the editors of McGraw-Hill; Mrs. Mary Ross who assembled the bibliography, figures, and contributor articles; Mrs. Mildred Sisko who typed the PMS and ISP Appendix; and especially Mrs. Dorothy Josephson who not only typed nearly all drafts of the book, but also the final PMS figures, and ISP Appendices.
C. Gordon Bell