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.
From what I'm to gather the phone switches themselves had their own processors.
But I have seen references to DEC PDP series computers being used to write the code, etc. for the switches.
As to processor requirements, I don't know but in the case of a switch the more critical component is the t/d matrix. All the computer does is keep track of call store which is nothing but a table.
Put it this way, I used to have a Definity G3iV2 switch (pbx actually!) with 300 extensions, and 35 trunk loops. It had an Intel
486 CPU on it.