15 Aug
2017
15 Aug
'17
6:13 a.m.
On Aug 14, 2017, at 8:57 PM, Greg 'groggy' Lehey <grog(a)lemis.com> wrote:
It was my understanding that the 704 had this
instruction [CAS] too, and
that it was almost certainly the background for arithmetic IF.
Unfortunately, no reference I can find can confirm or deny this
supposition. Another one is http://www.quadibloc.com/comp/cp0309.htm,
which compares the instruction sets, but it's not categorical enough
for my liking. But if I interpret it correctly, CAS was implemented
on the 704.
Do you see a proof of the contrary?
It turns out CAS is used in many places in the source code of the 4K and 8K drum versions
of the final IBM 704 FORTRAN II compiler. See
http://www.softwarepreservation.org/projects/FORTRAN/index.html#Source_code; in
particular:
Transcribed source:
http://www.softwarepreservation.org/projects/FORTRAN/source/fortran-ii/fort…
Assembly listing:
http://www.softwarepreservation.org/projects/FORTRAN/source/fortran-ii/fort…
I didn’t try to figure out if this code generates CAS, but it certainly uses it.