▁C . ▁Eric ▁Ell ings on ▁to ▁head ▁this ▁effort ▁and ▁Ell ings on ▁put ▁together ▁a ▁technical ▁team ▁to ▁purs ue ▁these ▁ideas . ▁ ▁Early ▁on ▁it ▁became ▁apparent ▁that ▁the ▁C AS OFF ▁architecture ▁was ▁sufficiently ▁radical ▁that ▁a ▁" proof ▁of ▁concept " ▁activity ▁was ▁needed ▁to ▁better ▁understand ▁and ▁ultimately ▁demonstrate ▁the ▁feas ibility ▁and ▁benefits ▁of ▁such ▁an ▁approach . ▁ ▁The ▁demonstr ation ▁system ▁used ▁a ▁synchron ized ▁Time ▁Division ▁Multiple ▁Access ▁architecture ▁and ▁incorpor ated ▁position ▁location ▁as ▁an ▁integral ▁part ▁of ▁the ▁communic ations ▁process . ▁ ▁Because ▁funds ▁were ▁extremely ▁limited ▁every ▁effort ▁was ▁made ▁to ▁use ▁already ▁available ▁equipment . ▁ ▁Trans mit ters ▁were ▁sur plus ▁AN / AP X - 2 5 ▁I FF ▁trans pond ers ▁and ▁data ▁processing ▁was ▁accomplished ▁using ▁sur plus ▁IBM ▁ 4 pi TC - 2 ▁computers ▁that ▁were ▁obtained ▁from ▁the ▁F - 1 1 1 ▁terrain ▁avoid ance ▁program . ▁The ▁unique ▁components ▁called ▁the ▁Control ▁and ▁Display ▁Units ▁( CD U ) ▁were ▁built ▁in ▁the ▁M IT RE ▁labor atory . ▁ ▁By ▁ 1 9 7 0 ▁an ▁operating ▁T D MA ▁system ▁had ▁been ▁constructed ▁and ▁ground ▁stations ▁were ▁installed ▁at ▁Boston ▁Hill ▁in ▁And over ▁MA , ▁Mill stone ▁Hill ▁in ▁Gro ton ▁MA , ▁M IT RE ▁in ▁Bed ford , ▁MA ▁and ▁Pro spect ▁Hill ▁in ▁W alth am , ▁MA . ▁ ▁An ▁air bor ne ▁terminal ▁was ▁also ▁installed ▁in ▁an ▁E SD