. ▁However , ▁some ▁European - only ▁games ▁such ▁as ▁Back ▁to ▁the ▁Future ▁Part ▁III ▁will ▁refuse ▁to ▁boot ▁on ▁N T SC ▁systems . ▁Japanese ▁games ▁can ▁be ▁run ▁on ▁Power ▁Base ▁Con verter ▁with ▁use ▁of ▁ad ap ters , ▁but ▁it ▁will ▁not ▁run ▁S G - 1 0 0 0 ▁games , ▁regardless ▁of ▁region . ▁ ▁Japanese ▁S ega ▁M ega ▁Drive ▁cart rid ges ▁have ▁a ▁different ▁shape ▁and ▁will ▁not ▁fit ▁in ▁the ▁Gen esis ▁or ▁P AL ▁M ega ▁Drive ▁slot , ▁which ▁have ▁the ▁same ▁shape ▁( although ▁the ▁Gen esis ▁ 3 ▁in ▁the ▁US ▁will ▁accept ▁Japanese ▁titles ▁due ▁to ▁its ▁wider ▁slot .) ▁Japanese ▁M ega ▁Drive ▁systems ▁have ▁a ▁piece ▁of ▁pl astic ▁that ▁sl ides ▁in ▁a ▁place ▁of ▁the ▁cart ridge ▁when ▁the ▁power ▁switch ▁is ▁turned ▁on , ▁thus , ▁inserting ▁an ▁American ▁or ▁European ▁cart ▁will ▁make ▁it ▁impossible ▁to ▁use ▁on ▁a ▁Japanese ▁MD ▁( though ▁minor ▁modifications ▁to ▁the ▁pl astic ▁lo cks ▁in ▁the ▁systems ▁will ▁by pass ▁this ). ▁The ▁console ▁main ▁board , ▁however , ▁was ▁designed ▁with ▁language ▁and ▁frequency ▁j um per ▁sets ▁which ▁originally ▁activ ated ▁features ▁in ▁the ▁same ▁R OM ▁for ▁the ▁different ▁regions . ▁This ▁feature ▁was ▁later ▁used ▁to ▁enable ▁software - based ▁regional ▁lo cks ▁that ▁display ▁warning ▁messages ▁that ▁prevent ▁the ▁game ▁from ▁being ▁played . ▁Switch es , ▁instead ▁of ▁the ▁jump ers , ▁were ▁used ▁to ▁by pass ▁the