The Starpath Supercharger was a cassette add on for the Atari 2600. It added higher resolution graphics, and expanded the Ram of the 2600 by a factor of 50, from 128 bytes to 6,272 bytes. The games made for the Supercharger were very impressive when compared to normal Atari games.
The Supercharger did not come with a cassette player, you had to provide your own. (A cord ran from the supercharger to the headphone jack).