In reading histories of IBM and the Bell System, my impression is that the companies were pretty distant from each other even though both were developing very similar technologies. Early on, both Bell and IBM were developing ever better ways of using relays to "think" in sophisticated ways, then using electronic components. (IBM obviously did go to Bell Labs to learn about the transistor).
While Bell used IBM machines in commercial (billing/ accounting) applications, even there Univac and other makes were used too. In the labs, it seemed mostly PDP computers were preferred.
Anyway, the Bell Labs history says Bell did make use of the IBM System/7 as part of the switching network. The S/7 was a process controller machine, kind of a sideline of IBM's normal business line. Anyway, Bell used the S/7 to replace AMA (long distance message accounting) machines. Even here the S/7 was eventually replaced with a PDP machine.
Would anyone know if there was some sort of hostility between Bell and IBM in the 1950s and 1960s? Or, am I just missing that there was a lot of collaboration?
Perhaps the lab histories of both companies prefers to focus on the company's own developments and ignore those elsewhere. The IBM history does give credit to semi-conductor makers. I sense Bell wanted to build everything it used for itself rather than buy finished products in the market.
(I presume both histories referenced below are authoritative sources. If anyone feels the Bell history is inaccurate, please do comment.)
I do note that the Bell history said they intended for very long product lifespans, so anything they made had to be able to withstand many years of service. I believe they didn't change this philosophy until the 1970s when rapidly changing electronics kept making components obsolete quickly. On the other hand, it seemed IBM recognized this in the 1950s. IBM's tab line remained unchanged for a great many years but their computers changed about every five years.
I also wonder if the commercial computer components of the 1960s (ie System/360 SLT chips and core memory) were adequate for the speed demanded by electronic switching. The Bell history suggests Bell had to develop its own gear because it needed faster speed and memory available in the commercial world on a cost- efficient basis. I believe an ESS of 1965 had quite a bit of memory and would compare to the largest commercial computers of that day.
References: History of Engineering & Science in the Bell System, Vol 2, switching, 1925-1975. IBM's System 360 and early S/370. IBM's Early computers.
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