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.

[1] 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.

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.

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.

Management decided against the plans, and as this essentially ended the ACS effort, Amdahl suggested they shut down the lab.

Instead of attempting to make the fastest computer using the most tightly packed circuit boards possible with current technology, they would instead design a much looser arrangement of five by five components on a standardized card.

A key concept in the system was the automated layout of the circuit board interconnections using software running on IBM 1130 computers.

[a] Looking for partners to produce the circuits, they found Motorola was interested in doing so as long as Amdahl would provide the routing software to them first.

After talking to National Semiconductor and Texas Instruments with no result, they finally signed with Advanced Memory Systems.

Much of this was due to the venture capital industry's feeling that attempting to compete with IBM was doomed; RCA had spent billions developing and marketing their Spectra 70 series and had yet to come close to a profit, while Xerox had attempted a different attack by buying Scientific Data Systems and was suffering as a result.

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.

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.

It also occupied one-third as much floor space, and as it lacked the water cooling system, it was much easier to install and maintain.

[12] In February 1977, Amdahl announced the 470V/6-II, which offered 5 to 15 percent greater performance but at a slightly higher cost.

[7] 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").

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.

Along the way, Amdahl came to believe that its best bet at competing with IBM head-to-head was to "bulk up", in particular, executing a merger with a well-known vendor in the enterprise storage space.

Most Amdahl mainframe customers would purchase storage devices (hard disk and tape drives) from IBM or its plug-compatible competitors.

By the early 1990s, Amdahl was suffering losses of several hundred million dollars per quarter as a result of declining mainframe sales.

Management decided to lay off 900 employees in 1992, 1,100 in early 1993, and another 1,800 (out of the 7,400 remaining) later in that year, as well as canceling hardware development projects in favor of reselling computers from Sun Microsystems.

[citation needed] Amdahl also failed in its effort to introduce its ObjectStar software (initially known as Huron) during this period and the product later became the object of a successful management buyout.

Some companies and governments still had Amdahl systems performing useful work into mid-2006, and Fujitsu/Amdahl promised support to those customers with replacement parts and other services through March 31, 2009.

The previous zSeries 800 also became an attractive replacement for Amdahl machines by late 2005 as that model's typical used price fell below $100,000 and continued to fall.

Using capital from Intel, Hewlett-Packard, Microsoft, and other major investors they designed a line of Itanium-based computers and software to emulate z/Architecture machines so that they could run zSeries operating systems, with zSeries channels for attaching real IBM equipment as well as virtual simulators for most hardware to minimize the need for IBM's peripheral equipment.

[24] The GS21 machines are essentially ESA/390 (31-bit) instruction set processors largely based on Amdahl-designed technologies but are only compatible with Fujitsu's domestic market operating systems: OSIV/MSP-EX and OSIV/XSP.