EMU_PTR
emu_wr(sc, EMU_PTR, ptr, 4);
emu_wr(sc, EMU_PTR, ptr, 4);
emu_wr_nolock(sc, EMU_PTR, ptr, 4);
emu_wr_nolock(sc, EMU_PTR, ptr, 4);
KASSERT(regno != EMU_PTR, ("emu_wr: attempt to write to EMU_PTR"));