Incompatibilities and Differences

• fcom and fef77 are incompatible in the way they fold REAL*4 constants. fcom promotes them internally to REAL*8.

• fcom allows more constant expressions in parameter statements than fef77.

• fcom allows lines longer than 256 characters by default; fef77 currently has a hard limit of 256.

• fef77 allows parameters (which are ignored) to the program statement.

• fef77 allows empty parameters in subroutine/function calls, which result in zeroes being passed by value.

• fef77 implements the Fortran 8x array syntax. (Fortran 8x is a subset of Fortran 90 that was implemented by various vendors before the Fortran 90 standard was complete).

• fef77 accepts PCF-style parallel directives in addition to the directives such as C$DOACROSS, which fcom accepts. PCF-style directives are documented in the MIPSpro Fortran 77 Programmer's Guide.