▁the ▁i Mac ▁in ▁ 1 9 9 8 , ▁which ▁uses ▁USB ▁in ▁its ▁place . ▁The ▁last ▁Apple ▁computer ▁to ▁have ▁an ▁Apple ▁Des ktop ▁Bus ▁port ▁is ▁the ▁Power ▁Mac int osh ▁G 3 ▁( Blue ▁and ▁White ) ▁in ▁ 1 9 9 9 . ▁Power PC - based ▁Power Book s ▁and ▁i Book s ▁still ▁used ▁the ▁Apple ▁Des ktop ▁Bus ▁protocol ▁in ▁the ▁internal ▁interface ▁with ▁the ▁built - in ▁keyboard ▁and ▁touch pad . ▁Sub sequ ent ▁models ▁use ▁a ▁USB - based ▁track pad . ▁ ▁Design ▁ ▁Phys ical ▁ ▁In ▁keeping ▁with ▁Apple ' s ▁general ▁philosophy ▁of ▁industrial ▁design , ▁Apple ▁Des ktop ▁Bus ▁was ▁intended ▁to ▁be ▁as ▁simple ▁to ▁use ▁as ▁possible , ▁while ▁still ▁being ▁in exp ensive ▁to ▁implement . ▁A ▁suitable ▁conne ctor ▁was ▁found ▁in ▁the ▁form ▁of ▁the ▁ 4 - pin ▁mini - D IN ▁conne ctor , ▁which ▁is ▁also ▁used ▁for ▁S - Video . ▁The ▁connect ors ▁are ▁small , ▁widely ▁available , ▁and ▁can ▁only ▁be ▁inserted ▁the ▁" correct ▁way ". ▁They ▁do ▁not ▁lock ▁into ▁position , ▁but ▁even ▁with ▁a ▁fr iction ▁fit ▁they ▁are ▁firm ▁enough ▁for ▁light ▁duties ▁like ▁those ▁intended ▁for ▁Apple ▁Des ktop ▁Bus . ▁ ▁Apple ▁Des ktop ▁Bus ▁protocol ▁requires ▁only ▁a ▁single ▁pin ▁for ▁data , ▁l abeled ▁Apple ▁Des ktop ▁Bus . ▁Two ▁of ▁the ▁other ▁p ins ▁are ▁used ▁for ▁+ 5 ▁V ▁power ▁supply ▁and ▁ground