PSW_R
frame->tf_ipsw |= PSW_R;
if (frame->tf_ipsw & PSW_R) {
#define db_clear_single_step(r) ((r)->tf_ipsw &= ~PSW_R)
#define db_set_single_step(r) ((r)->tf_ipsw |= PSW_R)
#define RESET_PSW (PSW_R | PSW_Q | PSW_P | PSW_D | PSW_I)
#define PSW_MBZ (PSW_Y | PSW_Z | PSW_S | PSW_X | PSW_M | PSW_R)