1 9 7 8 , ▁and ▁was ▁responsible ▁for ▁the ▁design ▁and ▁development ▁of ▁BB N ▁L IS P ▁at ▁Bol t , ▁Ber an ek , ▁and ▁New man , ▁developing ▁the ▁idea ▁of ▁a ▁programming ▁system ▁for ▁a ▁personal ▁computer . ▁He ▁used ▁the ▁AR P AN ET ▁to ▁support ▁users ▁of ▁BB N ▁L isp ▁at ▁Stan ford , ▁S RI , ▁US C , ▁and ▁C M U ▁in ▁ 1 9 7 0 , ▁and ▁has ▁been ▁named ▁an ▁official ▁AR P AN ET ▁P ione er , ▁for ▁his ▁contributions ▁to ▁its ▁development ▁and ▁growth . ▁ ▁He ▁developed ▁a ▁Program mer ' s ▁Ass istant ▁as ▁part ▁of ▁BB N - L IS P , ▁which ▁was ▁one ▁of ▁the ▁first ▁with ▁an ▁" Und o " ▁function , ▁by ▁ 1 9 7 1 . ▁ ▁He ▁developed ▁a ▁program ▁on ▁the ▁SD S ▁ 9 4 0 ▁for ▁Bob ▁K ahn ▁that ▁allowed ▁experiment ation ▁with ▁various ▁routing ▁policies ▁in ▁order ▁to ▁see ▁the ▁effect ▁on ▁network ▁traffic ▁and ▁real ▁time ▁monitoring ▁of ▁the ▁packets . ▁ ▁Inter l isp ▁and ▁D - L isp ▁He ▁worked ▁as ▁Senior ▁Scient ist ▁at ▁X ero x ▁P AR C ▁from ▁ 1 9 7 2 ▁until ▁ 1 9 8 4 ; ▁during ▁this ▁time ▁he ▁designed ▁Inter l isp . ▁Bill ▁Joy ▁has ▁acknowled ged ▁that ▁many ▁of ▁the ▁ideas ▁in ▁the ▁C ▁shell ▁were ▁inspired ▁by ▁and ▁copied ▁from ▁Inter l isp .