pddrb
pia(p)->pddrb = 255; /* all pins output */
pia(p)->pddrb = 0; /* all pins input */
s->u.amiga.datadir = pia(p)->pddrb;
s->u.amiga.statusdir = pia(p)->pddrb;
pia(p)->pddrb = s->u.amiga.datadir;
pia(p)->pddrb = s->u.amiga.statusdir;
pp->pddrb = 255; /* all data pins output */
dummy = pp->pddrb; /* reading clears interrupt */