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Some Favorite Things: The Evolution of IBM Z

June 04, 2018

This is the first of a few planned posts about what I would characterizes as “a few of my favorite things” like the lyric in the movie—you know which one. I am looking back over the last 40 years and I see at least four areas in IT where the impact of a certain kind of computing technology has had a huge impact on the industry and the world that it supports. Let me start with the machine.

The Beginning, My Beginning
I started in IT 40 years ago as a COBOL programmer. Businesses, in this case ConRail, were so needy that they took employees from departments where they were underutilized and turned them into programmers. I was an experiment as the only guy in a class of 12 programmers who knew nothing about computers. The other 11 had some background like a two-year community college program, and one guy had a master’s degree. Somehow, I got through the three-month course and ended up as a programmer on the transportation and billing team.

About six months into my new career, I started to wonder things like “What’s MVS and TSO?” I submitted jobs and browsed outputs, but what the heck was going on with the big C computer? My team leader, DJM, lent me his copy of “MVS Overview” and I was excited to learn a lot more about what happened when I submitted a job or read a file in a COBOL program. The organization of the MVS system was so comprehensive and detailed that I was in a bit of a state of shock reading it. I was amazed. Who invented all of this? Then I got a copy of “S/370 Principles of Operation” and I found the machine.

The Machine
The machine had main storage, CPU, I/O and a console. Simple enough. Then the details started to show signs of originality and vision like a vast number of instructions, the PSW, branching and interruptions, storage reference and serialization. Then CPU states, control modes, control registers, protection, time-of-day, DAT, and on and on. This machine was an engineering marvel full of controls and freedom. You had to play by the rules, be in the right state to do certain operations, but you had tremendous resources to draw upon—general instructions like ADD and MOVE and decimal instructions like ADD DECIMAL and ZERO AND ADD and hundreds more. It gave me a sense of wonder reading all this and trying to imagine it in operation. How did this all come about?

Then and Now
The thing is, the machine that is now called IBM Z has been growing and transforming this whole time—all through the 40 years since I first read about it. Many people know this but you still read, from time to time, that the mainframe is old fashioned or out of date. Not true. It’s a growing and changing universe of ideas and actions. The reason it’s thriving is because the whole eco system—the machine, the OS, the languages, the middleware and such—is constantly changing and improving through innovation and human ingenuity and millions and millions of dollars of investment.

The 12th edition of “z/Architecture Principles of Operation” tells the story of on-going growth, change and human invention. If you don’t know it, you must look at it. Use you IBM ID and password and start with the table of contents. What you will see is cosmic in scope. It’s a perfect universe of art and science and human imagination. It’s human in so many ways.

Does the Machine Have a Soul?
Remember the Tracy Kidder book “The Soul of a New Machine”? The IBM Z has a soul, a heart, a body and a brain, and it has supported many human lives over time. There are the legions of developers who designed and developed it and software companies that created other systems products and applications. There are the system programmers and application programmers—people working with COBOL and Java and every other language have earned a living allowing the platform to make the world a better place. In return, we have safer banking, insurance, science and medicine—you name it.

IBM Z fills me with wonder. If I can use a musical analogy, it’s the Chaconne (by Johann Sebastian Bach) of computer systems. I have studied the Chaconne and z/OS. I know their elements and parts and they all make sense to me but that does not explain the impact they have on me. They fill me with marvel that’s much more than the sum of their parts. I see in them genius—in one case, an individual and in the other, a community—but genius nevertheless. Take a few minutes with this offering and may it fill you with awe. And when you have a moment, ponder the z/Architecture. The place to start is “z/Architecture Principles of Operation.”

Next week, I have another “favorite thing” that I hope you will recognize.  

Posted June 04, 2018 | Permalink

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