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The IBM mainframe is 50 years old today

Still going after all these years
Mon Apr 07 2014, 09:30

ibm360-65THE IBM MAINFRAME COMPUTER architecture is 50 years old today.

International Business Machines (IBM) announced its IBM System/360 machines on 7 April, 1964, following years of engineering design and development that might have bankrupted Big Blue had the effort ultimately not been successful.

Then IBM chairman Thomas J Watson Jr believed in the project, however, so it drove to completion under chief architect Gene Amdahl and project manager Fred Brooks. John Opel managed the commercial launch of the IBM 360 family, which was very successful. (Opel would later hand control of the operating system for the IBM personal computer to the young Bill Gates, the son of a fellow United Way board member, indirectly leading to IBM's wrenching retrenchment during the mid-1990s.)

The IBM 360 mainframe computer architecture was the first to offer systems of different sizes and processing speeds that were architecturally compatible, thus enabling customers to buy bigger, faster machines as their businesses and computing needs grew without having to rewrite their libraries of applications programs.

Those first IBM mainframes were very slow by present standards, running at between one to 50MHz, and they didn't have much memory, with at minimum 8KB up to 8MB in the largest models. Semiconductor memory hadn't been invented then, so computers had memory built using tiny doughnut-shaped iron cores wired into addressable arrays, thus the term "core memory" entered the computing lexicon.

Big Blue rated its initial IBM mainframes' single CPU speeds at less than one million instructions per second (MIPS, otherwise known as a 'meaningless indicator of processor speed'), whereas it now claims that its largest zEnterprise System mainframes offer up to "over 4,900 MIPS" of aggregate processing power from up to 64 "n-way" CPUs in a single processing complex.

Over time, the System/360 range was superseded by the System/370, System/390, four zSeries ranges, System z9, System z10 and most recently zEnterprise System mainframes. Amazingly, with only minor restrictions, programs that ran on those earliest IBM System/360 mainframes still run on the latest and largest mainframes that IBM offers.

Today, mainframes power the massive volumes of transaction and backoffice processing that drive most of the large government organisations and corporate enterprises of modern life, from defence, taxation, healthcare and social welfare agencies through major banking, insurance, energy, manufacturing, transportation, distribution and retail companies.

Even though they are outnumbered millions to one by the large populations of internet servers, personal computers and mobile devices such as tablets and smartphones, mainframe computers are still crucial parts of our civilisation.

So raise a glass to the hulking mainframe today to celebrate its first 50 years. µ


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