@markd @stuartmarks @aka_pugs @JohnMashey Sure—and IBM did have excellent salespeople. But what should they have done? The IBM 7030 (https://en.wikipedia.org/wiki/IBM_7030_Stretch ) was a dead end, though the engineers learned a lot, and the IBM 8000 (https://en.wikipedia.org/wiki/IBM_8000) was canceled. IBM was by no means omniscient, and its attempts at smaller computers (the 1130 and 1800 and the 360/20 and /44) had much less interesting architectures than, say, the PDP-11 or the later VAX. It was by no means obvious, in 1964, that the S/360 was going to be a runaway market success, and it was very much a bet-the-company project. (Aside: Brooks offered his resignation to TJ Watson after the 8000 was canceled. Watson replied, "I just spent a billion dollars educating you; why should I fire you now?"—and Brooks became the chief architect of the S/360.)
There have been many technical criticisms of the S/360 architecture. Most of those concerned issues that Brooks, Blaauw, and Amdahl considered and rejected, e.g., a stack architecture, as infeasible given the technology of the time. And yes, they did make mistakes, as I pointed out earlier; the design was by no means perfect

@ncweaver.skerry-tech.com Nah—I don't see a vineyard.

@wendynather @cdarwin I have fewer words than that.

@JohnMashey @aka_pugs @markd The purpose of the higher-end machines was to sell the very profitable lower-end machine, by showing that there was an upgrade path. And then they blew it by having incompatible operating systems…

@markd @aka_pugs It's not clear to me that scientific computing declined in relevance then. But the S/360 line was, as @JohnMashey indicated, a way to unify the scientific and commercial lines of computers. (To be sure, on the lower-end models, the decimal instruction set and the floating point instruction set were options—and the 360/91 emulated the decimal instructions in the kernel (which IBM calls a nucleus).) One interesting way this was relevant: memory parity. Before the S/360, commercial computers had parity bits on memory; scientific ones did not. After all, commercial computers were used for things like banking, where you couldn't afford to lose money because of a hardware problem, whereas scientific computers were only used for things like bridge and nuclear reactor design, which of course don't cost money… There was also the moral issue—lives could be at stake—which was also Brooks' justification for insisting that all S/360s (including the /44, intended only for scientific computing) would have parity. The CDC 6600, a supercomputer of the day, did not have parity; the designer, Seymour Cray, said "Parity is for farmers" (https://en.wikipedia.org/wiki/ECC_memory#Personal_computers). The successor, the 7600, did have parity. (Note: to understand Cray's line, see https://en.wikipedia.org/wiki/Doctrine_of_parity.)

@stuartmarks @aka_pugs @JohnMashey @markd I checked what Blaauw and Brooks said about the S/360 floating point architecture. "The use of a hexadecimal base was intended to speed up the implementation, yet the resulting loss of precision was underestimated. The absence of a guard digit in the 64-bit format had to be corrected soon after the first machines were delivered."

@rose It's a tough balance!