David Stephens, a Systems Programmer, introduces Mainframes in clear, easy-to-understand English for Mainframe beginners as well as explains the IBM zSeries computing platform and z/OS operating system in his book What on Earth is a Mainframe? We asked Stephens a few questions about his reasons behind writing the book as well as the hardware, systems and terminology content to help readers understand this book and what it's all about. Stephens has also provided a free download of Chapter 1 of What on Earth is a Mainframe? for your personal viewing.
You write that there are lots of computing systems and software around that can help businesses wanting to use computers commercially. So why did you choose to write a book specifically about Mainframes? Why are they important?
I guess I consider Mainframes to be misunderstood. There are a lot of businesses that use zSeries Mainframes for their core business functionality, but don't have many people that understand what their Mainframe does and why they need it - particularly in management circles. So I wanted to write a book that people could digest in a few hours, and get a basic introduction to Mainframes.
You say that there aren't many organizations that will install a Mainframe from scratch, and that the number of Mainframes being used has dropped over the past years. Does this mean Mainframes will eventually die out, because no one is installing them?
That's a really good question, and one that's being talked about a lot at the moment. Existing Mainframe users will have a hard time moving their processing to something else, and IBM is getting way too much revenue from Mainframes to let them go without a fight. So I can't see them dying out. What I can see is the 'gap' between Mainframes and other platforms getting smaller and smaller. IBM has already moved down this path, with things like UNIX, TCPIP and Java now available on z/OS. IBM zSeries Mainframes are also becoming an option for Linux users with zLinux now available.
What audience did you have in mind while writing this book? What do you hope your audience walks away with after reading this book?
I really wrote the book for two kinds of people: Managers with Mainframes somewhere in their life, and technical people just starting with Mainframes or Mainframe related projects. The idea was that after reading the book, they'd walk away with enough knowledge to deal with Mainframe people, vendors and reports; and to be able to find out more information as they needed it.
How do businesses "evolve" around Mainframe programs and how do Mainframe programs evolve to suit businesses?
I believe this happens for any computer system, not just a Mainframe. Take a bank that introduces internet banking for example. As customers start using internet banking, the bank begins to offer more services - pay bills online, email the bank with questions, transfer money to friends. The banks also sees that they can save money when people use the internet, so they start reducing branch staff. You can see that internet banking has affected the bank's business.
Mainframe systems are like this, though they've had a couple of decades to become more entrenched.
With backward compatibility, you say it is more difficult for IBM to move to newer technology, but is it impossible?
Not at all - just harder. In fact zSeries Mainframes are evolving quite fast, and I've seen some radical changes over the past few years. If you look at the latest z10 processor family, you can see several significant technological changes.
Mainframes are a system based on older technology. Why does no one come up with a new system based on newer technology?
That's a good question, and I'd have to say backward compatibility. Mainframes today certainly do incorporate new technology, but still have to run programs that can be decades old.
If there weren't so many complications involved with moving away from Mainframes, do you believe businesses would still use them today?
I think some businesses definitely would keep their Mainframes - they still do a lot of things better than anything else. But I believe that if it was easy to move to other platforms, many more businesses would have made the change.
You write two reasons why people still use Mainframes is that they do certain things better and they are hard to move away from. Which reason outweighs the other?
That's difficult to say - it would really depend on the individual business, and the people involved. However I do believe that many businesses that have moved from the Mainframe now miss some of the Mainframe advantages they used to enjoy - particularly reliability and performance.