▁rel ays ▁or ▁ste pping ▁switch es ▁cont rolling ▁digits ▁consisting ▁of ▁inc and es cent ▁light ▁bul bs . ▁ ▁Begin ning ▁in ▁the ▁ 1 9 8 0 s , ▁adv ances ▁in ▁solid ▁state ▁electron ics ▁permitted ▁major ▁improvements ▁in ▁score board ▁technology . ▁ ▁High ▁power ▁sem icon duct ors ▁such ▁as ▁thy rist ors ▁and ▁trans ist ors ▁replaced ▁mechanical ▁rel ays , ▁light - em itting ▁di odes ▁first ▁replaced ▁light ▁bul bs ▁for ▁ind oor ▁score boards ▁and ▁then , ▁as ▁their ▁bright ness ▁increased , ▁out door ▁score boards . ▁ ▁Light - em itting ▁di odes ▁last ▁many ▁times ▁as ▁long ▁as ▁light ▁bul bs , ▁are ▁not ▁subject ▁to ▁break age , ▁and ▁are ▁much ▁more ▁efficient ▁at ▁converting ▁elect rical ▁energy ▁to ▁light . ▁ ▁The ▁new est ▁light ▁em itting ▁di odes ▁can ▁last ▁up ▁to ▁ 1 0 0 , 0 0 0 ▁hours ▁before ▁having ▁to ▁be ▁replaced . ▁ ▁Adv ances ▁in ▁large - scale ▁integrated ▁circ uits ▁permitted ▁the ▁introduction ▁of ▁computer ▁control . ▁ ▁This ▁also ▁made ▁it ▁cost ▁effective ▁to ▁send ▁the ▁signals ▁that ▁control ▁the ▁operation ▁of ▁the ▁score board ▁either ▁through ▁the ▁existing ▁AC ▁w ires ▁providing ▁power ▁to ▁the ▁score board ▁or ▁through ▁the ▁air . ▁ ▁Power line ▁mode ms ▁permit ▁the ▁digital ▁control ▁signals ▁to ▁be ▁sent ▁over ▁the ▁AC ▁power ▁lines . ▁ ▁The ▁most ▁common ▁method ▁of ▁sending ▁digital ▁data ▁over ▁power ▁lines ▁at ▁rates ▁less ▁than ▁