17 Feb
2025
17 Feb
'25
5:23 a.m.
On Feb 17, 2025, at 12:12 AM, ben via cctalk
<cctalk(a)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