[Simh] Fortran

[Robert Thomas]

We have used FORTRAN since the days when on IBM 1620's it was called GOTRAN.  We used DEC's FORTRAN on PDP-11/20's running DOS, upgraded hardware to run RSX-11M/ RSX-11M+ using the DEC FORTRAN.  Implemented various communications protocols including Cincinnati Milacron's rewrite of DECNET in FORTRAN and have moved all FORTRAN code to VAX, then AXP then Itanium on VMS.  There were very few code changes, most of those caused by newer compilers implementing the Character data type and then Intel/HP deciding on the Itanium to change how octal constants are coded.

The beauty of VMS is that in general the FORTRAN is upwards and backwards compatible, i.e. the same source from the Itanium VMS is just recompiled and relinked on VAX with no changes to the source.

We use Intel FORTRAN on Windows and find that it is for all intents compatible with FORTRAN on VMS.  WINDOWS does not support RMS, especially index file structures.  We have always jacketed O/S specific I/O where possible, especially ISAM I/O so that on each platform there is a set of subroutines that have identical call vectors that provide the O/S specific functionality.

The same FORTRAN code works on VMS and Windows.  The calculations return identical results even though on the VMS systems we use the DEC representation while on the PC's we use IEEE.

Sincerely,
Robert F. Thomas

 44 Industrial Way 
Norwood, MA USA 02062
N  Office Phone - (781) 329-9200
O mail to: rft at asthomas.com