> On Feb 17, 2025, at 12:12 AM, ben via cctalk <cctalk@classiccmp.org> wrote:
>
> Did any classic computers have a subroutine call as (S++)=PC, PC=(EFA)
> as well as the standard call (--S)=PC,PC=(EFA) ?
> One could have a virtual stack machine, using helper functions without
> having to deal with return addresses on the stack.
> Ben.
I don't know of any with what you describe. But there are machines that have
more than one flavor of subroutine call. VAX is one: CALL instruction that
buils a stack frame, and BSB that doesn't. Both use the SP, decrementing, for
the return information.
Then there is the Electrologica X8, which has a stack based subroutine call --
with the stack growing upward. But it also retains the EL-X1 style call
instructions that store the return address in one of 16 fixed low core
locations. I haven't seen code that used this, but one could certainly do so.
paul
