If you use a single DF command to compile and link, specify the /debug option (/debug sets the default optimization level to /optimize:0), as follows:
DF x.for /debug
By default, the debugger symbol table information is created in a PDB file, which is needed for the debugger integrated within the visual development environment.
If you use separate DF commands to compile and link, you will want to
specify the same debugging information level for the compiler and the
linker. For example, if you specify /debug:minimal to
the compiler, you will also specify /link /debug:minimal. The following
command sequence compiles and then links x.for
for debugging with
the integrated visual development environment debugger:
DF x.for /debug:full /optimize:0 /compile_only
DF x.obj /debug:full
For more information about preparing your command-line program for debugging, see Preparing Your Program for Debugging.