I try to use 'extended' type for variables but I cannot, turbo pascal 7.0 report 'Error 116: Must be in 8087 mode to compile this' - so I don't know if sbd can help me solve this.

turbo pascal 7? oh my that goes back a bit.

If you go to options, compiler, bottom right theres a numeric processing section, check the 8087/80287 option.