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Mainframe Computers Created a Sense of Wonder in Me

October 7, 2013

As we approach the 50th anniversary of the mainframe in 2014, I’ve been thinking about the elements that made an impression on me as a young computer programmer. In the beginning of my career, I studied the architecture of the mainframe computer. I didn’t have a degree in computer technology so all aspects of computing were new to me. I was hungry to understand whatever I could about how it worked. One of the best ways I found to do this was to read the “Principles of Operation” manual that was part of many in-house IT libraries. At first, I didn’t understand all that I read, but as I gained experience and education, I comprehended more of what was in that precise and detailed book. Here are two features that were key to my understanding. I will write about others in upcoming blog posts.

Language of the Machine

Studying Assembler Language was an empowering experience for a COBOL programmer. It was challenging, and it helped me make sense of the Principles of Operation manual. I became aware of the tremendous richness of the System/370 as there were a great variety of instructions that made it possible for me to write powerful and well-organized programs, and later on, large-scale applications.

Organization of the Entire System

After I understood more of the Assembler Language of the IBM mainframe, I began to appreciate the way that the technology was organized. I came to respect the hierarchy of computer storage from main memory to expanded storage then I/O with DASD and data sets supported by access methods. This order was persuasive and I could appreciate all these layers within the system and interact with them as necessary.

These were two characteristics that really amazed me. What surprised you? Please comment with your own thoughts and reflections.

Posted October 7, 2013| Permalink