▁address . ▁Once ▁this ▁comple tes , ▁that ▁device ▁is ▁marked ▁live , ▁and ▁the ▁system ▁continues ▁pol ling ▁it ▁in ▁the ▁future . ▁Once ▁all ▁of ▁the ▁devices ▁are ▁enumer ated ▁in ▁this ▁fashion , ▁the ▁bus ▁is ▁ready ▁to ▁be ▁used . ▁ ▁Although ▁it ▁was ▁not ▁common , ▁it ▁is ▁possible ▁for ▁the ▁Apple ▁Des ktop ▁Bus ▁bus ▁to ▁have ▁more ▁than ▁one ▁device ▁of ▁the ▁same ▁sort ▁plug ged ▁in ▁— ▁two ▁graphics ▁table ts ▁or ▁software ▁copy ▁protection ▁d ong les , ▁for ▁instance . ▁In ▁this ▁case ▁when ▁it ▁asks ▁for ▁devices ▁on ▁that ▁default ▁address , ▁both ▁will ▁respond ▁and ▁a ▁collision ▁could ▁occur . ▁The ▁devices ▁include ▁a ▁small ▁bit ▁of ▁timing ▁that ▁allows ▁them ▁to ▁avoid ▁this ▁problem . ▁After ▁receiving ▁a ▁message ▁from ▁the ▁host , ▁the ▁devices ▁wait ▁a ▁short ▁random ▁time ▁before ▁respond ing , ▁and ▁then ▁only ▁do ▁so ▁after ▁" s no op ing " ▁the ▁bus ▁to ▁make ▁sure ▁it ▁was ▁not ▁busy . ▁ ▁With ▁two ▁d ong les ▁plug ged ▁in , ▁for ▁instance , ▁when ▁the ▁bus ▁is ▁first ▁setting ▁up ▁and ▁queries ▁that ▁address , ▁one ▁of ▁them ▁will ▁be ▁the ▁first ▁to ▁respond ▁due ▁to ▁the ▁random ▁wait ▁timer . ▁The ▁other ▁will ▁notice ▁the ▁bus ▁was ▁busy ▁and ▁not ▁respond . ▁The ▁host ▁will ▁then ▁send ▁out ▁another ▁message ▁to ▁that ▁original ▁address , ▁but ▁since ▁one ▁device ▁has ▁moved ▁to ▁a ▁new ▁address , ▁only ▁the ▁other ▁will ▁then ▁respond .