The Amdahl 580 was a family of large mainframe computers designed by Amdahl Corporation. Like the earlier Amdahl 470V, the 580 series was plug compatible with IBM's System/370 series machines, but offered higher performance at a lower cost. The line was officially announced in November 1980, following IBM's announcement of their own new high-end system, the IBM 3081. The 5860 was the base model, a single-processor unit that ran about 50% faster than the 3081, and was twice as fast as Amdahl's own former top-end 470V/8. The 5880 was their new top-end design, using two 5860 processors and running up to 3.5 times the speed of the 470V/8. The new machines were first shipped in August 1982.
As was the case with the 470, Amdahl started at the high end and then released new members of the 580 line to match every new entry in IBM's lineup as they were introduced. This resulted in the various members of the 470 series being replaced by 580's, and by 1985 the switchover was complete. Many additional models were introduced to fill particular niches, ultimately resulting in systems with up to four processors, as well as new hardware that allowed multiple 580's to be loosely clustered. The family ultimately included dozens of different models in four generations, the original 580s, the 5980s, the 5890E's and the final 5990s announced in 1989. The 5990s were the first S/360 family machine to break the 100 MIPS performance level, and the 5995's of 1990 bumped this to 500 MIPS.
Through the 1980s, the performance advantage of the ECL circuitry was being eroded by modern CMOS designs. IBM had begun moving its mainframes to CMOS processors in the late 1980s and this gave Amdahl a performance lead for a period as CMOS was fundamentally slower than ECL. The 5990s were about 50% faster than IBM's fastest offerings, and garnered strong sales despite high costs. But IBM's bet paid off, and by the early 1990s CMOS could offer increasingly competitive performance for a tiny fraction of the cost. As sales crashed, in late 1993 Amdahl announced its own move to CMOS, and replaced the 580 family in late 1996 with the Amdahl Millennium series.
History Amdahl forms In the 1960s, IBM bundled software and support contracts with their computers for an all-in-one price. Software companies complained that this made it almost impossible to sell software to IBM users when they often had a free alternative. A series of lawsuits led to a 1969 announcement that IBM would no longer bundle software and that they would now be sold and billed separately from the hardware.
Gene Amdahl, known as the "father of the 360", had been working on the IBM Advanced Computer Systems project (ACS) in a new IBM facility in California. This project was becoming problematic and Amdahl was fighting with management right when the company announced the end of bundling. Amdahl realized this meant he could build a System/360 compatible computer and the customer could buy the operating system and other software from IBM. If IBM refused, they would be in violation of their anti-trust agreements. When the ACS project was shut down in May 1969, Amdahl began looking for investors to start a new company to produce a System/360 clone.
US investors were extremely skeptical. They pointed to RCA's Spectra 70 series which was mostly 360 compatible, but had failed to gain much marketshare. Other companies like General Electric, Univac and Xerox were also struggling against IBM's powerful sales force, as much any technical or pricing issue. Amdahl's plans were saved only due to his long relationship with Fujitsu, eventually convincing them to invest $5 million. This led to a surprise investment for another $5 million from Nixdorf, and that in turn led to Fujitsu adding another $5 million to maintain their primacy. Fully capitalized, Amdahl Corporation was officially formed in 1970.
470 concept The basic idea of the 470 family was to use then-modern large scale integration (LSI) to greatly reduce the size and power needs of an otherwise similar system using earlier chip designs. The System/370, announced shortly after Amdahl Corporation formed, used integrated circuits with about 35 transistors per chip. Amdahl was pushing for 100 per chip. They planned to install these in a five-by-five grid mounted to a circuit board that would allow them to mass produce the various larger logic units, as opposed to using wire wrap or similar techniques that were slower to produce and more expensive. Together, this would greatly reduce the cost of building the machines. It also had the added advantage that the resulting system was much smaller, and would use less power and produce much less heat, allowing it to be air-cooled. They would not have to greatly undercut IBM's prices, as the system as a whole would still have significantly lower total cost of ownership due to the smaller installation space, lower energy use, and the lack of water cooling that the high-end IBM systems required.
This meant that selling just the CPU, where IBM made only a part of its income, could still be profitable. For this to work, IBM could not simply lower its price to match. But Amdahl felt IBM could not change their pricing because of a longstanding policy selling low, medium and high-end systems that offered a step up of three in performance for double the price. This offered customers a strong incentive to upsize. However, as IBM made most of its money on low-end systems, the price of those systems was fixed, and the price of the higher-end was simply a function of the low-end pricing. This led to low profits at the high end, which IBM felt was endemic to the market, they did not see it for what it really was, a side effect of their sales plans. If Amdahl introduced a lower-cost system at the high-end, and IBM chose to match it while maintaining their pricing structure, they would be forced to sell the lower end systems at lower prices points as well, losing profit on their cash cow systems. Amdahl was convinced they would not do this.
The first member of the family, the 470V/6, was announced in 1974 and shipped the next year. For the entire year of 1976, the company managed to produce a profit margin of 30%, the same as IBM. IBM, who was previously convinced there was no way a company could be profitable selling just the CPU, suddenly realized their mistake. In March 1977 they announced a new series of systems, starting with the IBM 3033, which was aimed directly at the 470V/6 and outperformed it, but for higher costs and the water cooling requirements. Amdahl responded the same month by announcing their own series of machines that matched every other offering in the mid and lower-end parts of the 370 family, with the same advantages of slightly faster speeds and slightly lower prices. The next year they introduced a new high-end model, the V/8, that easily outperformed the 3033. By the early 1980s, the company held about 22% of the mainframe market share.
Development and release The 1970s were a period of dramatic improvement in semiconductor manufacturing, and the Amdahl designs which had been leading-edge when introduced were now obsolete. Gene wanted to press ahead with a new design that would have reduced the number of circuit boards by a factor of seven, but the engineers in the company were much more conservative and wanted a simpler approach. By this time, Fujitsu had largely assumed control of the company, and Gene became increasingly frustrated with their decisions, prompting him to leave in 1979 and form Trilogy Systems the next year.
The new design, the 580 family, was more of an updated 470 than a radical redesign. The basic layout using air-cooled LSI ECL chips mounted on circuit boards remained, as opposed to larger single chips. What changed was primarily the density, with the newer ICs having many more transistors, 400 up from 100, and the circuit boards expanding to eleven-by-eleven layout from six-by-seven. The result of these changes was to further reduce the size of the machine, which in turn allowed it to run faster as the signal pathways became shorter. Whereas the original V/6 ran at 32.5 ns, and the top-of-the-line V/8 at 26 ns, the 580 improved this slightly to 24 (~42 MHz). The same shrinking of the circuity allowed much more cache memory to be added, double that of the earlier machines, and newer dynamic RAM improved speeds from 320 ns in the V/8 to 280.
But the most important change for performance was a more complex processor pipeline. In the 470s, each instruction required two machine cycles to complete, at a minimum. In the 580, that was reduced to a single cycle. This did not by itself double the performance, as the CPU often ended up waiting more cycles for data to arrive. However, the new pipeline, combined with the larger caches, faster memory, and faster channel controllers, roughly doubled the overall performance compared to the V/8.
In November 1980, IBM announced two new models in the S/370 family, the new high-end IBM 3081, and the new mid-range 3033 Model S. The 3081 was about 1.5 times the speed of the 470V/8, the current high-end model from Amdahl, and priced more aggressively against it, a basic system being around $3,720,000 compared to $2,775,000 for the V/8. Amdahl responded on 18 November, less than a week after IBM's announcement, introducing the single-processor 5860 at $3,800,000 and the dual-processor 5880 at $7,500,000. The 5860 was roughly twice as fast as the V/8, easily outperforming the 3081. The 5880, essentially two 5860's running together, was 3.5 times as fast as the V/8, well over double that of the 3081. The 5860 could be upgraded in the field to a 5880 by adding another processor.
All of these machines took some time to deliver. The first to ship was the 3081, in late 1982, followed by the 5860 in April 1982. By this time IBM had built up a large order book for the 3081 that they were unable to fill, prompting a number of customers to cancel their orders and move to the 5860 instead. The first 5880 did not ship until late in 1983. During this time, IBM continued to introduce new models in the 3081 line, and Amdahl would, as they had in the past, announce a competing design to fill the same price points, but with higher performance.
Later models In October 1985, Amdahl announced a new lineup, the 5890 series, that used sub-model numbers. The primary difference was to improve the clock rate from 23.25 to 15 ns (43 to 67 MHz). The three machines were the 5890-200, -300 and -600, with the first two having two CPUs and differing largely in the amount of standard I/O channels, and the -600 having four processors. The -200 and -300 could be upgraded in the field to the -600. These were in turn replaced by the "E" models, announced in February 1987. The final evolution of the 580 series was the 5990, which moved to a 10 ns cycle (100 MHz) at 113 MIPS. IBM responded with their own 600S at the slightly slower 102 MIPS in October.
Amdahl also began to differentiate itself not on hardware, but increasingly with software. A significant feature during this period was their Multiple Domain Facility (sometimes Multiple Domain Feature) or MDF, which had first been introduced with the V/8 in November 1984. This allowed the operator to run completely different instances of the operating system on multi-processor systems. This facility was generalized over the years, including multiple "domains" per processor, and later, entirely different operating systems. This was particularly important when Amdahl announced their own UNIX System V, UTS Unix, which allowed operators to run their existing S/360 software in one domain and newer client/server Unix software in another. This was enormously successful and forced IBM to announce their own version, PR/SM, in 1988.
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