FORTRAN 66
FORTRAN 66 is perhaps the most significant development in the early history of FORTRAN was the decision by the American Standards Association (now ANSI) to form a committee to develop an “American Standard Fortran.” The resulting two standards, approved in March 1966, defined two languages, FORTRAN (based on FORTRAN IV, which had served as a de facto standard), and Basic FORTRAN (based on FORTRAN II, but stripped of its machine-dependent features). The FORTRAN defined by the first standard became known as FORTRAN 66 (although many continued to refer to it as FORTRAN IV, the language upon which the standard was largely based). FORTRAN 66 effectively became the first “industry-standard” version of FORTRAN.
FORTRAN 66 uses is fixed format coding and is designed around using numbers as labels to control "branching" to other areas of the program and terminating loops. Character string manipulation is very limited. Variable name length is limited.
FORTRAN 77 added support for a character data type, structured programming, array programming, modular programming, and generic programming. Still fixed format coding while the "standard" limits the line length to 72 character most compilers allow a line length of 132 characters. Structured programming eliminates the need for line numbers as labels. Character manipulation is better.
FORTRAN 90 added free format coding and better structured programming.
FORTRAN 95 added parallel computing.
FORTRAN 2003 added object-oriented programming.
FORTRAN 2008 added concurrent programming.
Intel Fortran
The Intel® Fortran Compiler is built on a long history of generating optimized code that supports industry standards while taking advantage of built-in technology for Intel® Xeon® Scalable processors, Intel® Xeon® processors, Intel® Core™ Ultra processors, and Intel® Core™ processors.
Staying aligned with Intel's evolving and diverse architectures, the compiler now supports GPUs.
The Intel Fortran Compiler is included in the Intel® oneAPI HPC Toolkit and in Intel® Fortran Essentials. Get the toolkit or essentials bundle to analyze, optimize, and deliver applications that scale.
Intel Fortran can be integrated as a tool into Microsoft Visual Studio.
GNU Fortran or GFortran
MinGW-W64:
MSYS2: A collection of Unix-like development tools, based on modern Cygwin and MinGW-w64.
Cygwin: A runtime environment that provides POSIX compatibility to Windows.
Windows Subsystem for Linux (WSL): An official compatibility layer for running Linux binary executables on Windows. With Windows Subsystem for Linux GUI one can run text editors and other graphical programs.
Open Watcom 2.0 Fortran 77 (open-watcom.github.io)
Watcom Fortran is a powerful Fortran compiler that includes an integrated development environment, debugger, and profiler, primarily used for developing applications in the Fortran programming language. It was well-known for its efficiency and support for various operating systems, including DOS and Windows.
Watcom Fortran is a powerful compiler designed for the Fortran programming language. It is part of the Watcom suite, which also includes C and C++ compilers. The Watcom Fortran compiler is known for its integrated development environment (IDE), debugger, and profiler, making it suitable for both beginners and experienced developers.
It supports DOS, Windows (16/32/64-bit), OS/2, and Linux (32/64-bit). The compiler generates 16/32-bit code only but can be installed on 64-bit systems. Note that the compilers only supports Fortran 66 and Fortran 77.