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An Introduction to Mainframes

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An Introduction to MainframesRijo Joseph05-Dec-2007

An Introduction to Mainframes

To

Reena Paulson AlapattMy sister and best friend

An Introduction to Mainframes

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PREFACE This is a humble effort to introduce mainframes DISCLAIMER No author writes a book without enormous help from others. I have drawn insights and ideas from many sources - from the IBM manuals to The Times of India Capital Edition. This book is a best effort on my part; I tried my level best to gather correct information from reliable sources. COPYRIGHT You can make as many copies of this book as you wish. I would be happy if you share it with others. You cant sell it, nor modify the contents of this book, nor claim the material as your own, nor replace my name with another. ABOUT THE AUTHOR Rijo Joseph holds Masters Degree in Computer Applications from University of Kerala (India) and at present working as a technical team lead with IBM India Pvt Ltd The author is IBM certified DB2 Associate, DB2 Application Developer, and Solutions Expert Your feedback is most welcome; send your comments to rijo.joseph@in.ibm.com ABOUT THE BOOK The book has been divided into two parts. The PART-1 contains information about computing history, computers, mainframes and mainframe OS and PART-2 contains Tips and Tricks and technical tidbits in COBOL, JCL, and DB2 etc BOOK EDITIONS Dec-05-07 First Edition The author shall have neither liability nor responsibility to any person or entity with respect to any loss or damages arising from the information contained in this book.

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ACKNOWLEDGEMENT It took me almost 3 years and a rigorous 2 months to complete this work. And I could say those 2 months were the toughest time in my life. The almighty chose those 2 months to teach me few tough lessons in life; however he made sure that my work is completed on time. Strange are your ways O Lord! I chose Dec 5 to publish this book as today is my sisters birthday. This book goes as a surprise birthday gift to my sister. She is the one who ignited a change in my life that enabled me to think beyond the boundaries I express my sincere gratitude to My parents, AV Joseph and Elsamma Joseph, my brother in law and sister, Paulson Jose Alapatt and Reena Paulson Alapatt, my cousins Fr. Benny Maramparampil and Sr. Tresa John for their love, support, guidance and prayers My managers at US Technologies - Saju Mathew, Sabu Purushothaman, Rajesh Subramony, Sunil Balakrishnan, Manjith Sundaresan and my managers at IBM India - Rajiv Mittal, Pawan Wig, Gautam K Varma, Santanu Dev for an unmatched support, motivation and guidance My SMEs, Managers and Technical Staff at Duke Energy/IBM US. This book goes as a souvenir for a 2 year long association with them. The motivation and help provided by Dave Miller, Tom Susman, Jim Kanet, Don Shull, and Grant Marsh were fantastic. They are a group of wonderful people. My friends, specifically to Lismi Sundaran, Nancy George, Sooraj Puthiyadath and Sarath Babu who made me believe that I could actually complete this work and most of the time they woke me up from my dreams and put me on my writing chair Sandeep Midha for providing me with the necessary reference books and Prateek Vijayvergia for providing me with necessary software for converting my work in MS Word to a .pdf format All the ghosts who came to interfere in my work, though you could take several days out of my schedule and you could crush me to the maximum, you couldnt do anything else. The baton is still in my hand and I have the final laugh. I enjoyed your presence, you taught me few lessons too. Thanks for that and better luck next time! I wanted to write a complete book, but I found it would take more years for me to complete, I followed a prototype approach. I will refine this book as and when I get valuable suggestions and advices from you. You can send your valuable suggestions to rijo.joseph@in.ibm.com or you can post your comments at http://www.geocities.com/rijosmailbox Rijo Joseph Dec-05-2007 An Introduction to Mainframes -4-

TABLE OF CONTENTS PART - 1 Chapter - 11. A Brief History of Computing ..................................................................................... 16 1.1. Abacus..................................................................................................................... 16 1.2. Napiers Bones........................................................................................................ 17 1.3. Blaise Pascal and Pascaline .................................................................................... 18 1.4. Gottfried Wilhelm Leibniz and Leibnizs calculator .............................................. 18 1.5. Joseph Marie Jacquard and Punched Cards ............................................................ 19 1.6. Charles Babbage ..................................................................................................... 20 1.7. Herman Hollerith and the Tabulating Machine ...................................................... 21 1.8. History of IBM........................................................................................................ 21 1.9. Generation of Computers........................................................................................ 22 1.9.1. Evolution of the First Generation of Modern Computers .............................. 22 1.9.2. The First Generation ...................................................................................... 23 1.9.2.1. ENIAC ....................................................................................................... 24 1.9.2.2. EDVAC...................................................................................................... 25 1.9.2.3. EDSAC ...................................................................................................... 25 1.9.2.4. UNIVAC I .............................................................................................. 25 1.9.3. The Second Generation.................................................................................. 26 1.9.4. The Third Generation..................................................................................... 26 1.9.5. The Fourth Generation................................................................................... 28 1.9.6. The Fifth Generation...................................................................................... 30

Chapter - 2

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Computer Classifications ............................................................................................. 32 2.1. Digital Computer .................................................................................................... 32 2.1.1. Special Purpose Computer............................................................................. 33 2.1.2. General Purpose Computer ............................................................................ 33 2.1.3. Microcomputer............................................................................................... 33 2.1.4. Minicomputer................................................................................................. 33 2.1.5. Mainframe Computer..................................................................................... 35 2.1.6. Super Computer ............................................................................................. 37 2.2. Analog Computer.................................................................................................... 40 2.3. Hybrid Computer .................................................................................................... 40

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Chapter - 33. More about Mainframes............................................................................................... 42 3.1. Factors Contributing to Mainframe use .................................................................. 43 3.1.1. Reliability, Availability, and Serviceability................................................... 43 3.1.2. Security .......................................................................................................... 43 3.1.3. Scalability ...................................................................................................... 43 3.1.4. Continuing Compatibility .............................................................................. 44 3.2. Typical Mainframe Workloads ............................................................................... 45 3.2.1. Batch Processing............................................................................................ 45 3.2.2. Online Transactional Processing.................................................................... 46 3.3. A peep into the history............................................................................................ 47 3.3.1. System/360..................................................................................................... 47 3.3.2. System/370..................................................................................................... 49 3.3.2.1. Multiprocessing ......................................................................................... 52 3.3.2.2. Channels .................................................................................................... 52 3.3.2.3. PR/SM........................................................................................................ 53 3.3.2.4. LPAR ......................................................................................................... 53 3.3.2.5. I/O Devices ................................................................................................ 53 3.3.2.5.1. Unit Record Devices............................................................................ 53 3.3.2.5.2. Magnetic Tape Dev