static MACHINE_CONFIG_START( mc1000, mc1000_state )
[...]
/* timers */
MDRV_TIMER_ADD_PERIODIC("ne555assert", ne555_tick, HZ(MC1000_NE555_FREQ))
MDRV_TIMER_PARAM(ASSERT_LINE)
MDRV_TIMER_ADD_PERIODIC("ne555clear", ne555_tick, HZ(MC1000_NE555_FREQ))
MDRV_TIMER_START_DELAY(HZ(MC1000_NE555_FREQ * 100 / MC1000_NE555_DUTY_CYCLE))
MDRV_TIMER_PARAM(CLEAR_LINE)
[...]
MACHINE_CONFIG_END