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Amdahl Corporation


Amdahl Corporation

Wholly owned subsidiary
Genre Information technology
Fate Bought over
Founded 1970
Founder Gene Amdahl
Defunct 1997
Headquarters Sunnyvale, California, United States
Products Mainframe computers, servers, software
Services Educational and consulting services
Parent Fujitsu

Amdahl Corporation was an information technology company which specialized in IBM mainframe–compatible computer products. 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 1
  • Market exit 2
  • Amdahl customer options 3
  • See also 4
  • References 5
  • External links 6

Company origins

Amdahl Corporation's logo, January 1976
Front panel of an Amdahl 4705 communications controller

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.[1] The first two 470V/6 machines were delivered to NASA (Serial Number 00001) and the University of Michigan (Serial Number 00002).[2][3] 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.

Market exit

By the early 1990s, Amdahl was suffering losses of several hundred million dollars per quarter as a result of dropping mainframe sales. Management decided to lay off 900 employees in 1992, 1,100 in early 1993 and another 1,800 (out of 7,400 remaining) later that year, cancelling hardware development projects in favor of selling Sun machines instead.[4]

Amdahl Corporation enjoyed perhaps its best sales during IBM's transition from bipolar to CMOS technology in the early to mid-1990s. At first IBM's new mainframe CMOS processors, the IBM 9672 G3 and G4, could not perform as well as spare-no-expense bipolar technology, giving Amdahl a temporary advantage. However, IBM's CMOS strategy paid off in the long run, allowing IBM's Poughkeepsie factory to produce even faster mainframes at lower cost as the technology matured. By the time IBM introduced its breakthrough 64-bit zSeries 900 in 2000, it was all over for Amdahl's hardware business, which, by Fujitsu's ill-decided edict, only had 31-bit-addressing Millennium and OmniFlex servers to sell. In late 2000, Fujitsu/Amdahl announced that the company had no plans to invest the estimated US $1 billion (or more) to create an IBM-compatible 64-bit system.

Amdahl also failed in its effort to introduce ObjectStar software (initially known as Huron) during this period and that product later became the object of a successful management buy out (MBO). ObjectStar was subsequently acquired by integration software vendor TIBCO in 2005.

Amdahl customer options

z/OS 1.5 is the last release of IBM's flagship operating system still able to run on 31-bit mainframes, including Amdahl and older IBM systems. IBM effectively ended support for z/OS 1.5 on March 29, 2007.[5] In May 2006, IBM announced that the next version of z/VSE, Version 4, would require a 64-bit system, signaling the end to 31-bit support for that operating system. z/TPF, which became available in December 2005, also requires a 64-bit system. The 31-bit Linux distributions will survive as long as the open source community and distributors have interest. So while there is still some potential life for Amdahl's hardware, the transition to 64-bit systems is essentially complete. 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.

Arguably IBM did not have a suitable replacement model for many Amdahl customers until the May 2004 introduction of the zSeries 890. 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. The System z9 BC model, introduced in May 2006, increased IBM's attractiveness yet again, and the BC drove z800 and z890 prices down even more. The late 2008 introduction of the IBM System z10 BC yet again made IBM's equipment more enticing. In fact, Fujitsu/Amdahl now sells used IBM mainframes and offers services to migrate customers to the IBM machines. (This migration is straightforward and comparable to upgrading from one IBM model to a newer IBM model.) Other, generally less attractive options include running without support, rewriting applications, or possibly running applications under FLEX-ES.[6] FLEX-ES is a mainframe instruction set emulator that supports ESA/390 and, in some cases, z/Architecture operating systems and software.

The vestiges of Amdahl's ESA/390 emulation project were resurrected under a new name: Platform Solutions Inc. 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. Its LPARs hosted not only IBM operating systems but 64-bit Intel Itanium Linux, HP-UX, Solaris, and potentially other operating systems.

Platform Solutions started shipping its machines in the first quarter of 2007. This action precipitated a lawsuit from IBM, citing patent infringement and PSI's failure to negotiate a z/Architecture license, and IBM refused to license its operating systems and software on PSI's machines. Platform Solutions countered that by “tying” the sale of its software to the sale of its hardware, IBM was in violation of its prior anti-trust agreement with the U.S. Justice Dept. In July 2008, IBM acquired PSI, and both companies dropped their lawsuits against each other.[7] PSI's machines are no longer available.

Fujitsu continues to sell its "GlobalServer" (GS21) mainframe models in the Japanese domestic market. 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. MSP is most similar to classic IBM MVS/ESA, and XSP is most similar to classic IBM VSE/ESA. Fujitsu GS21 mainframe hardware would most closely correspond to late 1990s IBM G5 or G6 mainframes in terms of their instruction set support. Fujitsu has stated the company has no intention to license or implement Z/Architecture (64-bit). Hitachi continues to operate its domestic Japanese mainframe business in similar fashion.

See also


  1. ^ "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.
  2. ^ "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.
  3. ^ "Michigan Accepts Amdahl 470 After Tests", Don Leavitt, Computerworld, Vol. IX, No. 42, 15 October 1975, p. 1. Accessed 10 April 2015.
  4. ^ Bozman, Jean S. (8 November 1993). "Amdahl tries to rightsize its business". Computerworld. p. 10. 
  5. ^ "ADCD z/OS MP3000 Support Status". Retrieved 2008-11-03. 
  6. ^ FLEX-ES.
  7. ^ "IBM Acquires Platform Solutions". 2008-07-02. Archived from the original on 5 September 2008. Retrieved 2008-09-06. 

External links

  • Amdahl 470 V-6 Machine Reference, 50 pages, 1975, PDF/A, 7.8MB.
  • Amdahl 470 V-6-II Machine Reference Manual, 50 pages, March 1978, PDF/A, 9.4MB.
  • Amdahl 470V/8 Computing System Machine Reference Manual, April 1981, PDF/A, 3.8MB.
  • Several Amdahl publications are available online as PDFs from
  • Amdahl 470V/6, P2 is in storage at the Computer History Museum, catalog X436.84A.
  • Photographs of an Amdahl 470V/6 at the Computer History Museum, Mountain View, California.
  • Photographs of an Amdahl 470V/6 at the University of Michigan.
  • Photographs of an Amdahl 5860 at the University of Newcastle, 1984-1992.
  • Oral history interview with Gene Amdahl Charles Babbage Institute, University of Minnesota, Minneapolis. Amdahl discusses his graduate work at the University of Wisconsin, his role in the design of several computers for IBM including the STRETCH, IBM 701, 701A, and IBM 704. He discusses his work with Nathaniel Rochester.
  • System/390 Compatible Servers – Overview of Amdahl servers from Fujitsu Computer Systems, owner of Amdahl
  • System/390 Compatible Servers – Overview of Hitachi AP8000/MP-series
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