1 2 ▁disk ▁drive , ▁among ▁other ▁improvements , ▁added ▁buffer ed ▁seek ▁cap ability ▁to ▁the ▁interface . ▁In ▁this ▁mode , ▁the ▁controller ▁can ▁send ▁S TE P ▁p uls es ▁to ▁the ▁drive ▁as ▁fast ▁as ▁it ▁can ▁receive ▁them , ▁without ▁having ▁to ▁wait ▁for ▁the ▁mechanism ▁to ▁sett le . ▁An ▁on board ▁micro processor ▁in ▁the ▁drive ▁then ▁moves ▁the ▁mechanism ▁to ▁the ▁desired ▁track ▁as ▁fast ▁as ▁possible . ▁The ▁ST 5 0 6 ▁disk ▁drive ▁without ▁buffer ed ▁seek ▁aver ages ▁ 1 7 0   ms ▁( similar ▁to ▁a ▁flo ppy ▁drive ▁or ▁modern ▁optical ▁drive ) ▁while ▁the ▁mechan ically ▁very ▁similar ▁ST 4 1 2 ▁disk ▁drive ▁with ▁buffer ed ▁seek ▁aver ages ▁ 8 5   ms . ▁By ▁the ▁late ▁ 1 9 8 0 s , ▁drives ▁with ▁an ▁ST 4 1 2 ▁interface ▁were ▁capable ▁of ▁average ▁seek ▁times ▁between ▁ 1 5 ▁and ▁ 3 0 ▁mill iseconds . ▁ ▁The ▁process ▁of ▁moving ▁port ions ▁of ▁the ▁command ▁interpretation ▁off ▁the ▁controller ▁card ▁and ▁onto ▁the ▁drive ▁itself ▁in ▁order ▁to ▁improve ▁performance ▁is ▁a ▁common ▁feature ▁of ▁later ▁hard ▁drive ▁connection ▁schemes , ▁not ably ▁SC SI , ▁with ▁its ▁rich ▁command ▁set , ▁and ▁the ▁storage - f oc used ▁IDE ▁systems . ▁IDE , ▁in ▁effect , ▁is ▁a ▁system ▁for ▁extending ▁the ▁computer ▁bus ▁so ▁the ▁interface ▁controller ▁can ▁be ▁built ▁into ▁the ▁drive ▁unit ▁rather ▁than ▁being ▁plug ged ▁into