> No, it's not.  There are various existance proofs from history to
> contradict this.  Up until the mid 1970s or so it was common for
> "minicomputers" so store the return address of a subroutine in the
> first location of the subroutine.  Just don't try to do recursive
> calls.  The PDP-8 was like that for one.  I've worked with other more
> obscure machines that also used this architecture, like a Varian 620-I
> and a small computer made by Honeywell that I can't remember the model
> name of.

And now that I think about it some more, the IBM 360 didn't inherently use a
stack for storing subroutine return addresses.  Subroutines were generally
called with the BALR (branch and link register) instruction, although there
were other subroutine call options.  BALR saved the return address in a
register, and it was up to the subroutine to deal with that and eventually
return to that address.  The 360 may have had auto inc/dec addressing modes,
so that a software managed stack was easily possible, but I don't think the
hardware call or interrupt mechanism assumed the existance of a stack.
Certainly the IBM 360 was about as mainstream as it gets in the early 1970s.


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