Entertainment Computer System

The Entertainment Computer System (or ECS) was an add-on peripheral for the Mattel Intellivision that converted the system into a home computer. It was Mattel's second attempt at marketing such a peripheral, with the previous attempt, the Intellivision Keyboard Component, aborted after a test market run. It consisted of the ECS add-on module which plugged into the Intellivision and an alphanumeric computer keyboard.