"Despite its name, the TX802 FM Tone Generator is basically a rack-module version of the DX7mkII with full 8-part multi-timbral operation for sequencing and/or key mapping. It has 16-voices of polyphony and six digital FM Operators, the same as in the DX7mkII. There are 128 preset and 64 user patches for your sounds, as well as an external memory cartridge slot.
As if the large keyboard DX versions weren't difficult enough to program, the TX802's limited interface makes editing and programming your own sounds next to impossible without the help of external hardware or software editors."
You're better off getting a new Yamaha synth…someone was selling it below….though !