[TUHS] origin of string.h and ctype.h

Paul McJones paul at mcjones.org
Tue Aug 15 14:13:41 AEST 2017

On Aug 14, 2017, at 8:57 PM, Greg 'groggy' Lehey <grog at 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/fort1.asm.html
Assembly listing: http://www.softwarepreservation.org/projects/FORTRAN/source/fortran-ii/fort1.lst.html

I didn’t try to figure out if this code generates CAS, but it certainly uses it.

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