The TX816 contains up to 8 modules, each of which is equivalent to a DX7 FM synth (16 voices, 6 operators). So if yours has all 8 modules then you have 8 DX7s in a box, each on its own MIDI channel.
The CX5M has a number of program ROM cartridges available for it, one of which is a DX7 editor. If you got that cartridge with it, you could use it to program the TX816. But if not, use the CX5M as a doorstop or boat anchor and get a PC or Mac based editor for your TX.
Two VCO: thanks to the push rods, one can choose several forms of waves at the same time!
(from a Babelfish translation of a Jupiter-6 site)
Yamaha: Motif XS6, TX802 Roland: D-550 Alesis: A6 Andromeda