At the end of August, IBM announced the latest member of its mainframe family, the zEnterprise EC12. As pointed out in the announcement, the new system is a result of more than $1B in R&D investments over the past four years, resulting in major improvements in performance, security, availability and other key enterprise features. But perhaps, what is most impressive about this announcement, is the longevity of the IBM mainframe, which is now in its 48th year. Few computer families having major announcements in 2012 could trace their vintage to the 1980s, let alone the 1960s. There is something pretty unique about the mainframe being not only alive but well after all these years.
I have had a long association with mainframes. I was a second year college student at the University of Chicago when the System 360 was first announced in April of 1964. At the time, I was also working part time at the university’s computation center which used IBM computers. I still remember attending a presentation on the announcement given by a visiting IBM technical executive. Later on as a physics graduate student, I used high-end S/360 models for my thesis research. In IBM, I was closely associated with mainframes through major portions of my 37 year career, in particular, the period from 1977-1992 when I was involved in a number of R&D initiatives on the future of the mainframe.
To a large extent, the mainframe’s longevity is a result of two major architectural innovations first introduced with S/360. The first was the notion of a family of computers, from low to high performance, all based on the same instruction set which allowed customers to upgrade to larger systems as well as to future system models without having to rewrite their applications. The second was OS/360, a common operating system that supported the various members of the S/360 family except for the smaller ones which ran DOS/360, a subset with more limited capabilities. Today’s z/Architecture and z/OS are direct descendants of the original S/360 and OS/360.
Through the 1960s, 1970s and 1980s, mainframes were built using highly sophisticated and expensive technologies. It was important to get the maximum efficiency and price-performance out of each machine, so the hardware architecture and operating system were carefully designed to achieve high processor utilizations and fast response times to high volume transactions. Over the years, the IBM mainframes have continued to carefully design the hardware and operating systems software together to optimize performance and industrial strength, e.g., security, systems management, availability and other ilities.
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