SLIPDISC
case SLIPDISC:
int slipdisc = SLIPDISC;
disc = SLIPDISC;
linesw[SLIPDISC] = slipdisc;
if (tp->t_line == SLIPDISC) {
tp->t_line = SLIPDISC;
case SLIPDISC:
ldisc = SLIPDISC;