can u sugest a site where i can get free FORTRAN-77 software?

Question

and plz do tell what are compilers too?
thanks in advance!

Answer 1

I agree with TJ. BTW, do a search and there are plenty, like:
Salford FTN77 PE ANSI Fortran 77 Compiler
The Salford FTN77 PE (Personal Edition) comes with a full optimising ANSI Fortran 77 compiler with support for various common extensions (including MIL-STD-1753), linker, libraries, make utility, librarian and a full screen debugger. The compiler has a built-in assembler for inline assembly, and the ability to link with code from other sources (such as C++ Fortran 90 and Fortran 95 code). It is free for personal use and for use by students. It supports Windows 95, 98 and NT.

Open Source Watcom / OpenWatcom Fortran Compiler
The Watcom (now OpenWatcom) Fortran 77 compiler is now available free of charge, complete with source code. This compiler, which generates code for Win32, Windows 3.1 (Win16), OS/2, Netware, MSDOS (16 and 32 bit), etc, was a well-known compiler some years back (until Sybase terminated it).

MinGW'S G77 (GNU Fortran)
This system comes with the GNU G77 Fortran compiler (among other things, including a C/C++ compiler), which you can use to generate Win32 executables from F77 code. Like many systems based on the GNU tools, Mingw32 comes with complete with various programming tools, such as a program maintainence program (ie, make), text processing tools (sed, grep), lexical analyser generator (flex), parser generator (bison), etc.

DJGPP GNU G77 (Fortran 77) for MSDOS
This is a development system based on the well-known GNU compiler system that includes compilers for Fortran 77, C, C++, Objective C, etc. It generates 32 bit MSDOS executables that is Windows 95 long-filename-aware. It is a very complete system with IDEs, graphics libraries, lexical analyser generators (flex), parser generators (bison), text processing utilities (like grep, sed), a program maintainence utility (ie, make), a dos extender, and so on. The compiler, utilities and libraries come with source code.

Answer 2

What do you mean "software"? Do you mean FORTRAN-77 applications written in FORTRAN, or do you mean software for compiling FORTRAN-77?

You can find some commercial and free compilers listed here: http://en.wikipedia.org/wiki/Fortran#FORTRAN_77

By your second question, I guess you want to know what are some compilers? If so, see above. If you mean, what IS a compiler, post it as additional info and I'll amend my answer.