DP says:
Description: A cassette recorder with a cartridge interface. An additional wire connects the recorder to the joystick port. Voices and songs from the cassette instruct the player what to do on the screen. The tape shuts itself off automatically to allow the input. Three cassettes (Smurfs Save the Day) came in the package. Only one other title, Berenstain Bears, is compatible with this unit. Released in 1983.

From the Digital Press "Classic" Guide.
This should be in the finds thread, but I congratulate you! A very impressive piece of video game equipment!