int osh ▁models , ▁on ▁later ▁models ▁of ▁Ne XT ▁computers , ▁and ▁saw ▁some ▁other ▁third - party ▁use ▁as ▁well . ▁Like ▁the ▁similar ▁PS / 2 ▁conne ctor ▁used ▁in ▁many ▁PC - compat ibles ▁at ▁the ▁time , ▁Apple ▁Des ktop ▁Bus ▁was ▁rapidly ▁replaced ▁by ▁USB ▁as ▁that ▁system ▁became ▁popular ▁in ▁the ▁late ▁ 1 9 9 0 s ; ▁the ▁last ▁external ▁Apple ▁Des ktop ▁Bus ▁port ▁on ▁an ▁Apple ▁product ▁was ▁in ▁ 1 9 9 9 , ▁though ▁it ▁remained ▁as ▁an ▁internal - only ▁bus ▁on ▁some ▁Mac ▁models ▁into ▁the ▁ 2 0 0 0 s . ▁ ▁History ▁ ▁Apple Bus ▁Early ▁during ▁the ▁creation ▁of ▁the ▁Mac int osh ▁computer , ▁the ▁engineering ▁team ▁had ▁selected ▁the ▁fairly ▁s oph istic ated ▁Z ilog ▁ 8 5 3 0 ▁to ▁supply ▁serial ▁communic ations . ▁This ▁was ▁initially ▁done ▁to ▁allow ▁multiple ▁devices ▁to ▁be ▁plug ged ▁into ▁a ▁single ▁port , ▁using ▁simple ▁networking ▁protocol s ▁implemented ▁inside ▁the ▁ 8 5 3 0 ▁to ▁allow ▁them ▁to ▁send ▁and ▁receive ▁data ▁with ▁the ▁host ▁computer . ▁ ▁During ▁development ▁of ▁this ▁Apple Bus ▁system , ▁computer ▁networking ▁became ▁a ▁vit ally ▁important ▁feature ▁of ▁any ▁computer ▁system . ▁With ▁no ▁card ▁sl ots , ▁the ▁Mac int osh ▁was ▁unable ▁to ▁easily ▁add ▁support ▁for ▁E ther net ▁or ▁similar ▁local ▁area ▁networking ▁standards . ▁Work ▁on ▁Apple Bus ▁was ▁re - direct ed ▁to ▁networking ▁purposes ,