This mean looking Yamaha TX-816 just arrived! The TX-816 is a monstrous FM synth from the 80’s. It’s actually eight (!) Yamaha DX7s in a 4U rack.
Each “DX7” is called a TF1 module, the TX-816 has eight TF1s. Two cheaper versions were also sold, the TX-216 and TX-416 with two respectively four TF1s. Those were of course upgradable to TX-816 by adding additional TF1 modules. When new in 1984 a TX-816 cost more than $5000. I payed less than $400 which is a bargain.
This particular unit was used on the big hit “Highland” from the early nineties. I don’t know if that’s good or bad. It was a bargain anyway, got it for a good price since the second module shows error number 4, which actually is no worse than low battery. In other words, the internal battery must be unsoldered and replaced.