RCA's TRK-5, TRK-9 and TRK-12 has a socket to allow connection of a phonograph attachment. The R-100 plays 78 rpm records and was introduced at the 1939 World's Fair as an accessory for RCA's television sets. The record on our phonograph was recorded by a family at the fair (mp3 format). Thanks to Cliff Benham for converting this to digital format.