I had a Panasonic portable "Walkman" style cassette player in 1983 and if memory serves, it did not have a radio, had to be pulled open manually with the cassette in the door. It had a strap and a belt clip. I have been wanting to find one for quite some time but from all the photos I have seen on google, none are of the player I had in highschool
Time for some Window shopping in the 1983 Panasonic Catalogue http://wegavision.pytalhost.com/Technics/1983-1/