single-level store idea, planned to succeed IBM S/370 architecture, product development effort started in 1971, reputed to have cost more than $1B, cancelled in February 1975, but the ideas developed into System/38, AS/400, and iSeries
Six months after the announcement of the IBM System/360 in April of 1964, planning for a NGS (next generation system) began. NGS later became known as NS (new systems, and also later next system) and eventually as the System/370 in June of 1970. Because of the success in the S/360 sales and the problems with conversions, by 1966, plans for NS from Dick Case's architecture and technology department within SDD (systems development division) emphasized "evolution, not revolution" [Pugh, et al., p. 478].
In 1969 and 1970 an economic slowdown and then recession affected the computer inductry. Unlike the previopus boom years, growth in IBM's mainframe revenue vanished. With predictions of dramatic price drops in transistorized memory and disk memory coming within the next ten years, the IBM CTC (Corporate Technical Committee) felt that a new architecture was needed: "This is a major undertaking and a task equal to, if not larger than, our change to System /360." [Dec. 1970, quoted by Pugh, et al., p. 542] A task force led by John Opel was set up in August 1971. The task force reviewed several proposals before choosing George Radin's proposal for a single-level store, capability-based architecture. This architecture became known as FS (future system).
Radin proposed three layers:
By the middle of 1972, engineers at Endicott and Boeblingen argued that they should only have to provide the single top-level interface, the ADI. A compromise was reached that the engineers could directly implement the EDI, with the ADI still provided by a compiler. This was called the FSM (FS machine). Pugh, et al., describe the FS system architects feeling that this was a "power play by engineers who desired to gain increased responsibility" [p. 548].
By the fall of 1974, the FS schedule had slipped several times, and the IBM S/370 systems were selling well. Memory and disk prices had not dropped as dramatically as predicted, and thus Bob Evans made a decision to extend the architecture of S/370.
Pugh, et al., note that the Rochester group charged with planning for a replacement for System/3 met several times with the FS architects and "embraced many of the FS design concepts" [p. 552]. The System/38 was announced in October 1978 and delivered in July 1980. System/38 later became known as AS/400, and more recently as the iSeries.
Current iSeries overview. An earlier version of this overview included this text:
No other computing platform has such a powerful architecture as SLS. It's patented. As simple as it sounds, it's also an immense effort to effectively implement. SLS is a result of some of the most forward-thinking ideas. In fact, the design, in development, was named "FS" for Future System.
Note the coverage of FS and what they describe as its "toxic aftereffects" on the corporation in Chapter 3 of Charles Ferguson and Charles Morris, Computer Wars: The Post-IBM World, Times Books, 1993. An excerpt:
Most corrosive of all, the old IBM candor died with F/S. Top management, particularly Opel, reacted defensively as F/S headed toward a debacle. The IBM culture that Watson had built was a harsh one, but it encouraged dissent and open controversy. But because of the heavy investment of face by the top management, F/S took years to kill, although its wrongheadedness was obvious from the very outset. "For the first time, during F/S, outspoken criticism became politically dangerous," recalls a former top executive."
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