▁the ▁first ▁Trans mission ▁Control ▁Pro tocol ▁( T CP ) ▁specification , ▁ ▁( Spec ification ▁of ▁Internet ▁Trans mission ▁Control ▁Program ), ▁written ▁by ▁V int ▁Cer f , ▁Y ogen ▁Dal al ▁and ▁Carl ▁Sun sh ine ▁in ▁ 1 9 7 4 . ▁This ▁became ▁the ▁foundation ▁of ▁U sen et , ▁conce ived ▁by ▁Tom ▁Tr usc ott ▁and ▁Jim ▁Ell is ▁in ▁ 1 9 7 9 ▁at ▁the ▁University ▁of ▁North ▁Carolina ▁at ▁Chap el ▁Hill ▁and ▁Duke ▁University , ▁and ▁established ▁in ▁ 1 9 8 0 . ▁ ▁A ▁prec ursor ▁of ▁the ▁electronic ▁bullet in ▁board ▁system ▁( B BS ), ▁known ▁as ▁Community ▁Memory , ▁had ▁already ▁appeared ▁by ▁ 1 9 7 3 . ▁True ▁electronic ▁bullet in ▁board ▁systems ▁arrived ▁with ▁the ▁Computer ▁Bul letin ▁Board ▁System ▁in ▁Chicago , ▁which ▁first ▁came ▁online ▁on ▁February ▁ 1 6 , ▁ 1 9 7 8 . ▁ ▁Before ▁long , ▁most ▁major ▁cities ▁had ▁more ▁than ▁one ▁B BS ▁running ▁on ▁TR S - 8 0 , ▁Apple ▁II , ▁At ari , ▁IBM ▁PC , ▁Com mod ore ▁ 6 4 , ▁S inc la ir , ▁and ▁similar ▁personal ▁computers . ▁The ▁IBM ▁PC ▁was ▁introduced ▁in ▁ 1 9 8 1 , ▁and ▁subsequent ▁models ▁of ▁both ▁Mac ▁computers ▁and ▁PC s ▁were ▁used ▁throughout ▁the ▁ 1 9 8 0 s . ▁ ▁Multiple ▁mode ms , ▁followed ▁by ▁special ized ▁tele communic ation ▁hardware ,