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Amdahl Corporation was an information technology company which specialized in IBM mainframe–compatible computer products, some of which were regarded as supercomputers competing with those from Cray Research. Founded in 1970 by Dr. Gene Amdahl, a former IBM computer engineer best known as chief architect of System/360, it has been a wholly owned subsidiary of Fujitsu since 1997. The company is located in Sunnyvale, California. Amdahl was a major supplier of large mainframe computers, and later of UNIX and open systems software and servers, data storage subsystems, data communications products, application development software, and a variety of educational and consulting services. In the 1970s, when IBM had come to dominate the mainframe industry, Amdahl created plug-compatible machines that could be used with the same hardware and software as offerings from IBM, but were more cost-effective. Boasting faster uniprocessors, the largest single image, greater performance characteristics and higher reliability, the Amdahl mainframe was compelling to buyers who were willing to consider alternatives to IBM. These machines gave "Big Blue" some of the little competition it had in that very high-margin computer market segment. Proverbially, during this time savvy IBM customers liked to have Amdahl coffee mugs visible in their offices when IBM salespeople came to visit. While winning about 8% of the mainframe business worldwide, Amdahl won a position of market leader in some regions, most notably Charlotte, North Carolina. In the early to mid-1990s, Amdahl won most of the major contracts for mainframes in the Carolinas. == Company origins == Amdahl Corp. launched its first product, the Amdahl 470/6, in 1975, competing directly against IBM's high-end machines in the then-current System/370 family, but with IBM's announcement of Dynamic Address Translation (DAT), Amdahl announced the 470V/6 and dropped the 470/6. (At IBM, Gene Amdahl had co-designed the groundbreaking 32-bit architecture, 24-bit addressing, System/360 line of computers. Applications written for the System/360 can still run, unmodified, on today's zSeries mainframes four decades later.) At the time of its introduction, the 470V/6 was less expensive but still faster than IBM's comparable offerings.〔("A Performance Comparison of the Amdahl 470V/6 and the IBM 370/168" ), Emery, Allan R., and Alexander, M.T., Computer Measurement Group, October 1975, San Francisco, California.〕 The first two 470V/6 machines were delivered to NASA (Serial Number 00001) and the University of Michigan (Serial Number 00002).〔("Amdahl 470 Up to 130% Faster Than 2M-Byte 370/168 in Tests" ), Patrick Ward, ''Computerworld'', Vol. IX, No. 37, 10 September 1975, p. 1. Accessed 10 April 2015.〕〔("Michigan Accepts Amdahl 470 After Tests" ), Don Leavitt, ''Computerworld'', Vol. IX, No. 42, 15 October 1975, p. 1. Accessed 10 April 2015.〕 For the next quarter century Amdahl and IBM competed aggressively against one another in the high-end server market, with Amdahl grabbing as much as 24% marketshare. Amdahl owed some of its success to antitrust settlements between IBM and the U.S. Department of Justice, which ensured that Amdahl's customers could license IBM's mainframe software under reasonable terms. Dr. Gene Amdahl was committed to expanding the capabilities of the uniprocessor mainframe during the late 1970s and early 1980s. Amdahl engineers, working with Fujitsu circuit designers, developed unique, air-cooled chip designs using high speed ECL (Emitter-coupled logic) circuit macros packaged in a chip with a heat-dissipating cooling attachment (looked like the heat-dissipating fins on a motorcycle engine) mounted directly to the top of the chip. This patented technology allowed the Amdahl mainframes of this era, unlike IBM systems, to be completely air-cooled, and did not require "plumbing" for chilled water. In the 470 systems, the chips were mounted in a 6x7 array on multi-layer cards (up to 14 layers), which were then mounted in vertical columns. The cards had eight connectors that attached the micro-coaxial cables that interconnected the system components. A conventional backplane was not used in the central processing units. The card columns held at least three cards per side (two per column in rare exceptions, say, in the processor's "C-Unit"). Each column had two large "Tarzan" fans (a "pusher" and a "puller") to move the considerable amount of air needed to cool the chips. In the 580 systems, the chips were mounted in an 11-by-11 array on multi-layer boards called Multi-Chip Carriers (MCCs) that were positioned in high airflow for cooling. The MCCs were mounted horizontally in a large rectangular frame. The MCCs slid into a complex, physical connection system and the processor "side panels" interconnected the system, providing clock propagation delays that maintained race-free synchronous operation at relatively high clock speeds (15–18 ns base clock cycles). This processor box was cooled by high speed fans generating horizontal air flow across the MCCs. Additional models of Amdahl uniprocessor systems included the 470V/5, /7 and /8 systems. The 470V/8, first shipped in 1980, incorporated high speed 64K cache buffers to improve performance, and the first real hardware based virtualization (known as "Multiple Domain Facility"). Amdahl also pioneered a variable speed feature on the V5 and V7 systems that allowed the customer to run the CPUs at a higher performance level when necessary. The customer was charged by the number of hours used. Some at Amdahl thought this feature would anger customers, but it became quite popular as management could now control expenses while still having "afterburner" speed available when necessary. Gene Amdahl left the company he founded in 1980, moving on to start a couple of new technology companies. With Gene Amdahl's departure, and increasing influence from Fujitsu, Amdahl broke into large system multi-processor design in the mid-80's with the 5870 (attached processor) and 5880 (full multiprocessor) models. Amdahl under the leadership of Tom O'Rourke entered the IBM Peripherals business in Front End Processors and Storage Products and these products were very successful for a number of years with the support of Jack Lewis, former CEO of Amdahl. Reliance upon a single product, within the complex business of mainframes and their equally valuable peripherals, doomed the hardware part of the company when market forces shifted to Intel-based processors. This had been foreseen leading to an increasing emphasis on software and consulting services. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Amdahl Corporation」の詳細全文を読む スポンサード リンク
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