1 , ▁but ▁with ▁fundamental ▁short com ings ▁im posed ▁by ▁the ▁OS ▁It ▁was ▁much ▁faster ▁than ▁the ▁V AX , ▁but ▁did ▁not ▁meet ▁the ▁general ▁customers ' ▁expectation ▁of ▁being ▁a ▁multi - pur pose ▁computer . ▁Later ▁models ▁improved ▁the ▁performance ▁and ▁twe aking ▁of ▁the ▁system ▁allowed ▁it ▁to ▁become ▁a ▁multip ur pose ▁system ▁at ▁the ▁performance ▁of ▁a ▁special ▁purpose ▁super ▁computer ▁as ▁sold ▁by ▁C ray . ▁A ▁major ▁contract ▁with ▁the ▁N D - 5 0 0 ▁was ▁the ▁J oint ▁European ▁Tor us ▁project , ▁which ▁took ▁delivery ▁of ▁twenty - se ven ▁N D - 1 0 0 ▁and ▁- 5 0 0 ▁units . ▁Development ▁of ▁the ▁N D - 5 0 0 0 ▁started ▁before ▁the ▁N D - 5 0 0 ▁was ▁completed . ▁The ▁design ▁was ▁changed ▁to ▁become ▁more ▁mod ular ; ▁this ▁increased ▁the ▁development ▁costs , ▁but ▁reduced ▁production ▁costs ▁and ▁increased ▁scal ability . ▁On ▁the ▁N D - 5 0 0 0 , ▁components ▁were ▁placed ▁in ▁cards ▁that ▁were ▁inter connected , ▁initially ▁to ▁simplify ▁cool ing ▁but ▁also ▁to ▁enable ▁the ▁high ▁clock ▁frequency . ▁If ▁an ▁electric ▁current ▁is ▁switched ▁at ▁a ▁clock ▁frequency ▁of ▁ 1 G Hz , ▁it ▁travel s ▁about ▁one ▁foot ▁per ▁cycle , ▁so ▁ 1 0 cm ▁is ▁a ▁delay ▁of ▁a ▁clock ▁cycle ▁at ▁ 3 G Hz . ▁The ▁N D - 5 0 0 ▁computers ▁had ▁timing ▁problems ▁caused ▁by