aha! feenableexcept! i'd never heard of it!

    // Demonstrate C99/glibc 2.2+ feenableexcept

    #define _GNU_SOURCE
    #include <math.h>
    #include <fenv.h>
    #include <stdlib.h>
    #include <stdio.h>

    int main(int argc, char **argv)
    {
      if (argc != 3) {
        fprintf(stderr, "Usage: %s a b  # floating-point divide a by b\n", argv[0]);
        return 1;
      }

      feenableexcept(FE_DIVBYZERO);
      double a = atof(argv[1]), b = atof(argv[2]);
      printf("%g ÷ %g = %g\n", a, b, a/b);
      return 0;
    }

is the machine still ieee-754-compliant after you call feenableexcept? i'm guessing that if it weren't, intel wouldn't have defined the architecture to have this capability, given the historically close relationship between 8087 and ieee-754