fdsetpos
fdsetpos(sc, dmatrk, write);
fdsetpos(sc, sc->cachetrk % FDNHEADS, 0);
fdsetpos(sc, sc->cachetrk, 0);
fdsetpos(sc, sc->cachetrk + FDNHEADS, 0);
void fdsetpos(struct fd_softc *, int, int);
fdsetpos(sc, 0, 0);
fdsetpos(sc, sc->type->ncylinders, 0);
fdsetpos(sc, 0, 0);
fdsetpos(sc, 0, 0);
fdsetpos(sc, FDNHEADS, 0);
fdsetpos(sc, 0, 0);