Stephane, When trying out a build with --enable-sim-build-warnings=,-Werror(1) I noticed: case 0x19: /* daa a->a */ src8 = cpu_get_a (proc); cpu_special (proc, M6811_DAA); cpu_set_a (proc, dst8); break; (the generated file m68hc11int.c) GCC is complaining that dst8 might be used uninitialized. enjoy, Andrew (1) No one has tried this for a long time