▁optional ▁compatibility ▁feature ▁that ▁helps ▁users ▁of ▁IBM ▁ 1 4 0 0 ▁series ▁computers ▁migr ate ▁to ▁System / 3 6 0 . ▁ ▁With ▁the ▁additional ▁Comp at ibility ▁Fe ature ▁hardware ▁and ▁Comp at ibility ▁Support ▁software ▁under ▁D OS / 3 6 0 , ▁the ▁IBM ▁ 1 4 0 1 / 1 4 4 0 / 1 4 6 0 ▁object ▁programs ▁can ▁be ▁run ▁in ▁the ▁em ulation ▁mode , ▁with ▁little ▁or ▁no ▁re programming . ▁ ▁System ▁configuration ▁The ▁standard ▁set ▁of ▁peri pher als ▁is ▁available , ▁although ▁by ▁this ▁time ▁customers ▁had ▁found ▁their ▁way ▁to ▁IBM - compatible ▁alternatives . ▁ ▁A ▁typical ▁System / 3 6 0 ▁Model ▁ 2 5 ▁configuration ▁consists ▁of : ▁IBM ▁ 2 0 2 5 ▁CPU ▁IBM ▁ 1 0 5 2 ▁console ▁printer - key board ▁IBM ▁ 2 5 4 0 ▁card ▁reader - p unch ▁IBM ▁ 1 4 0 3 ▁printer ▁One ▁or ▁more ▁IBM ▁ 2 3 1 1 ▁or ▁IBM ▁ 2 3 1 4 ▁disk ▁drives ▁One ▁or ▁more ▁magnetic ▁t ape ▁drives , ▁either ▁IBM ▁ 2 4 1 5 ▁or ▁IBM ▁ 2 4 0 1 ▁model ▁ 1 , ▁attached ▁to ▁the ▁selector ▁channel ▁ ▁Software ▁The ▁typical ▁operating ▁system ▁for ▁the ▁Model ▁ 2 5 ▁was ▁D OS / 3 6 0 , ▁which ▁was ▁loaded ▁from ▁disk . ▁Less ▁common ▁was ▁T OS / 3 6 0 , ▁which ▁was ▁loaded ▁from ▁t