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 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 was located in Sunnyvale, California.
From its first machine in 1975, Amdahl's business was to provide mainframe computers that were plug-compatible with contemporary IBM mainframes, but offering higher reliability, running somewhat faster, and costing somewhat less. They often had additional practical advantages as well, in terms of size, power requirements, of being air-cooled instead of requiring a chilled water supply. This offered a price/performance ratio superior to the IBM lineup, and made Amdahl one of the few real competitors to "Big Blue" in the very high-margin computer market segment. The company won about 8% of the mainframe business worldwide, but was a market leader in some regions, most notably in the Carolinas. Proverbially, savvy IBM customers liked to have Amdahl coffee mugs visible in their offices when IBM salespeople came to visit.
As the mainframe market began to change in the later 1980s, Amdahl was increasingly diversified, becoming a major supplier 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.
Company origins
Amdahl launched its first product in 1975, the Amdahl 470/6, which competed directly against high-end models in IBM's then-current System/370 family. When IBM announced the introduction of Dynamic Address Translation (DAT), Amdahl announced the 470V/6 and dropped the 470/6. At the time of its introduction, the 470V/6 was less expensive but still faster than IBM's comparable offerings. The first two 470V/6 machines were delivered to NASA (Serial Number 00001) and the University of Michigan (Serial Number 00002). For the next quarter-century Amdahl and IBM competed aggressively against one another in the high-end mainframe market. At its peak, Amdahl had a 24% market share. 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.
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 chips which were based on high-speed emitter-coupled logic (ECL) circuit macros. These chips were packaged in a chip package with a heat-dissipating cooling attachment (that looked like the heat-dissipating fins on a motorcycle engine) mounted directly on the top of the chip. This patented technology allowed the Amdahl mainframes of this era to be completely air-cooled, unlike IBM systems that required chilled water and its supporting infrastructure.
In the 470 systems, the chips were mounted in a 6-by-7 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, such as 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. Each system included a Data General Nova 1200 programmed to support the CRT console and to accept the same channel command operations as the IBM 3066 on the 370/165 and 370/168.
Additional models of Amdahl uniprocessor systems included the 470V/5, /7 and /8 systems. The 470V/8, first shipped in 1980, incorporated high speed 64 KB cache memories to improve performance, and the first real hardware-based virtualization (known as the "Multiple Domain Facility").
Amdahl also pioneered a variable-speed feature - the '470 accelerator' - on the /5 and /7 systems that allowed the customer to run the CPUs at the higher level of performance of the /6 and /8 systems, respectively, when desired. 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 customer management could now control expenses while still having greater performance available when necessary.