1 ▁Control ▁Unit ▁attach es ▁card ▁readers , ▁card ▁p unch es ▁and ▁line ▁printer s ▁to ▁the ▁IBM ▁System / 3 6 0 ▁and ▁IBM ▁System / 3 7 0 ▁families ▁of ▁computers . ▁The ▁devices ▁attached ▁are ▁as ▁follows : ▁ ▁The ▁IBM ▁ 2 5 4 0 ▁card ▁reader ▁and ▁card ▁p unch ; ▁ ▁The ▁IBM ▁ 1 4 0 3 ▁models ▁ 2 , ▁ 3 , ▁ 7 ▁and ▁N 1 ▁line ▁printer ; ▁and ▁ ▁The ▁IBM ▁ 1 4 0 4 ▁model ▁ 2 ▁line ▁printer ▁and ▁card ▁reader . ▁ ▁Six ▁models ▁of ▁the ▁IBM ▁ 2 8 2 1 ▁Control ▁Unit ▁were ▁available , ▁as ▁follows : ▁ ▁Model ▁ 1 ▁attached ▁one ▁IBM ▁ 2 5 4 0 ▁and ▁one ▁IBM ▁ 1 4 0 3 ; ▁ ▁Model ▁ 2 ▁attached ▁one ▁IBM ▁ 1 4 0 3 ; ▁ ▁Model ▁ 3 ▁attached ▁two ▁or ▁three ▁IBM ▁ 1 4 0 3 s ; ▁ ▁Model ▁ 4 ▁attached ▁one ▁IBM ▁ 2 5 4 0 ▁and ▁one ▁IBM ▁ 1 4 0 4 , ▁but ▁only ▁on ▁IBM ▁System / 3 6 0 ▁models ▁ 2 5 , ▁ 3 0 , ▁ 4 0 ▁and ▁ 5 0 ; ▁ ▁Model ▁ 5 ▁attached ▁one ▁IBM ▁ 2 5 4 0 ▁and ▁two ▁or ▁three ▁IBM ▁ 1 4 0 3 s ; ▁and ▁ ▁Model ▁ 6 ▁attached ▁one ▁IBM ▁ 2 5 4 0 . ▁