▁R ally ▁for ▁N intendo ▁Entertainment ▁System ▁( N ES ) ▁in ▁ 1 9 9 1 , ▁also ▁released ▁as ▁Stadium ▁M ud ▁B ugg ies ▁for ▁Int ell iv ision ▁in ▁ 1 9 8 9 . ▁ ▁Lic ens ing ▁agre ements ▁with ▁N intendo ▁and ▁S ega ▁required ▁IN TV ▁Corporation ▁to ▁dis continue ▁the ▁Int ell iv ision ▁in ▁ 1 9 9 0 . ▁IN TV ▁Corporation ▁did ▁publish ▁ 2 1 ▁new ▁Int ell iv ision ▁cart rid ges ▁bringing ▁the ▁Int ell iv ision ▁library ▁to ▁a ▁total ▁of ▁ 1 2 4 ▁cart rid ges ▁plus ▁one ▁compilation ▁cart ridge . ▁ ▁T utor vision ▁ ▁In ▁ 1 9 8 9 ▁IN TV ▁Cor p ▁and ▁World ▁Book ▁Encyclopedia ▁entered ▁into ▁an ▁agreement ▁to ▁manufact ure ▁an ▁educational ▁video ▁game ▁system ▁called ▁T utor vision . ▁ ▁It ▁is ▁a ▁modified ▁Int ell iv ision , ▁the ▁case ▁m old ed ▁in ▁light ▁be ige ▁with ▁gold ▁and ▁blue ▁trim . ▁ ▁The ▁Exec ▁R OM ▁expanded , ▁system ▁RAM ▁increased ▁to ▁ 1 . 7 5 K , ▁and ▁graphics ▁RAM ▁increased ▁to ▁ 2 KB . ▁ ▁That ▁is ▁enough ▁graphics ▁RAM ▁to ▁define ▁unique ▁graph ic ▁t iles ▁for ▁the ▁entire ▁screen . ▁ ▁Games ▁were ▁designed ▁by ▁World ▁Book , ▁J . ▁H ak ans son ▁Associ ates , ▁and ▁program med ▁by ▁Re alt ime ▁Associ ates . ▁ ▁Six teen ▁titles ▁were ▁in ▁production , ▁plus ▁one