The Importance of Terminology's Quality

[Piet van Oostrum]

>>>>> Arne Vajhøj <arne at vajhoej.dk> (AV) wrote:

>AV> Robert Maas, http://tinyurl.com/uh3t wrote:
>>> John W Kennedy <jwke... at attglobal.net> wrote:
>JWK> Into the 60s, indeed, there were still machines being made
>JWK> that had no instruction comparable to the mainframe BASx/BALx
>JWK> family, or to Intel's CALL. You had to do a subprogram call by
>JWK> first overwriting the last instruction of what you were
>JWK> calling with a branch instruction that would return back to
>JWK> you.
>>> 
>>> That's not true, that you needed to do that, that there was no
>>> other way available. The subroutine linkage I invented for S.P.S.
>>> (Symbolic Programming System, i.e. IBM 1620 assembly language) was
>>> to reserve a 5-digit space immediately before the subroutine entry
>>> point for storing the return address. So the caller needed to know
>>> only one address, the entry point, and do both store-return-address
>>> and jump relative to that address, rather than needing to know both
>>> the entry point and the last-instruction-JUMP-needs-patch address
>>> as independent items of information.

>AV> CDC Cyber did something very similar.

>AV> Not very recursion friendly.

Actually, the CYBER way wasn't too bad. IIRC the CYBER had a subroutine
instruction that stored the return address in the location that the
instruction referenced and then jumped to the address following that
location. To implement a recursive procedure you started the code of the
procedure with saving the return address to a stack.
-- 
Piet van Oostrum <piet at cs.uu.nl>
URL: http://pietvanoostrum.com [PGP 8DAE142BE17999C4]
Private email: piet at vanoostrum.org