extern double PITCONST;
void pit_init();
void pit_ps2_init();
void pit_reset(PIT *pit);
void pit_set_gate(PIT *pit, int channel, int gate);
void pit_set_using_timer(PIT *pit, int t, int using_timer);
void pit_set_out_func(PIT *pit, int t, void (*func)(int new_out, int old_out));
void pit_clock(PIT *pit, int t);


void pit_null_timer(int new_out, int old_out);
void pit_irq0_timer(int new_out, int old_out);
void pit_irq0_timer_pcjr(int new_out, int old_out);
void pit_refresh_timer_xt(int new_out, int old_out);
void pit_refresh_timer_at(int new_out, int old_out);
void pit_speaker_timer(int new_out, int old_out);